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HUMAN    PHYSIOLOGY. 


A   TREATISE 


HUMAN    PHYSIOLOGY 


DESIGNED   FOR  THE   USE   OF 


STUDENTS  AND  PMCTITIONERS  OF  MEDICINE. 


BY 


JOHN  C.  DALTON,  Jr.,  M.  D., 

PROFESSOR  OF  PHYSIOLOGY  AND  MICROSCOPIC  ANATOMY  IN  THE  COLLEGE  OP  PHYSICIANS  AND  SURGEONS, 

NEW   YORK;    MEMBER   OF   THE   NEW   YORK    ACADEMY   OF   MEDICINE;     OF   THE   NEW   YORK 

PATHOLOGICAL  SOCIETY;  OF  THE  AMERICAN  ACADEMY  OF  ARTS  AND  SCIENCES, 

BOSTON,  MASS.  ;    AND  OP  THE    BIOLOGICAL   DEPARTMENT  OF  THE 

ACADEMY  OF  NATURAL  SCIENCES  OF  PHILADELPHIA. 


WITH  TWO  HUNDRED  AND  FIFTY-FOUR  ILLUSTPuATIONS. 


PHILADELPHIA: 
BLANCHAUD     AND     LEA. 

1859. 


/rsf 


Entered  according  to  the  Act  of  Congress,  in  the  year  185 9^  by 

BLANCHARD    AND    LEA, 

in  the  Office  of  the  Clerk  of  the  District  Court  of  the  United  States  in  and  for  the 
Eastern  District  of  the  State  of  Pennsylvania. 


PHILADELPHIA: 
COLLINS,  PRINTER,  705  LODGE  ALLEY. 


TO  MY  FATHER, 


JOHN  C.  DALTON,  M.D., 


HOMAGE    OF    HIS    LONG    AND     SUCCESSFUL    DEVOTION 


SCIENCE  AND  ART  OF  MEDICINE, 


GRATEFUL  RECOLLECTION  OP   HIS  PROFESSIONAL  PRECEPTS  AND  EXAMPLE, 


%\lh  Bahnu 


IS  RESPECTFULLY  AND  AFFECTIONATELY 


INSCRIBED. 


'mm 


PREFACE. 


This  volume  is  offered  to  the  medical  profession  of  the  United 
States,  as  a  text-book  for  students,  and  also  as  a  means  of  commu- 
nicating, in  a  condensed  form,  such  new  facts  and  ideas  in  physio- 
logy, as  have  marked  the  progress  of  the  science  within  a  recent 
period.  Many  of  these  topics  are  of  great  practical  importance  to 
the  medical  man,  as  influencing,  in  various  ways,  his  views  on 
pathology  and  therapeutics ;  and  they  are  all  of  interest  for  the 
physician  who  desires  to  keep  pace  with  the  annual  advance  of  his 
profession,  as  indicating  the  present  position  and  extent  of  one  of 
the  most  progressive  of  the  departments  of  medicine. 

It  has  been  the  object  of  the  author,  more  particularly,  to  pre- 
sent, at  the  same  time  with  the  conclusions  which  physiologists 
have  been  led  to  adopt  on  any  particular  subject,  the  experimental 
basis  upon  which  those  conclusions  are  founded ;  and  he  has  en- 
deavored, so  far  as  possible,  to  establish  or  corroborate  them  by 
original  investigation,  or  by  a  repetition  of  the  labors  of  others. 
This  is  more  especially  the  case  in  that  part  of  the  book  (Section 
I.)  devoted  to  the  function  of  Nutrition ;  and  as  a  general  thing, 
throughout  the  work,  any  statement  of  experimental  facts,  not 
expressly  referred  to  the  authority  of  some  other  writer,  is  given 
by  the  author  as  the  result  of  direct  personal  observation. 

The  illustrations  for  the  work  have  been  prepared  with  special 
reference  to  the  subject-matter ;  and  it  is  hoped  that  they  will  be 
found  of  such  a  character  as  materially  to  assist  the  student  in 
comprehending  the  most  important  and  intricate  parts  of  the  sub- 
ject. It  is  more  particularly  in  the  departments  of  the  Nervous 
System  and  Embryonic  Development  that  simple,  clear,  and  faithful 


Vlll  PREFACE. 

illustrations  are  indispensable  for  tlie  proper  understanding  of  the 
printed  descriptions ;  the  latter  being  often  necessarily  somewhat 
intricate,  and  requiring  absolutely  the  assistance  of  properly 
arranged  figures  and  diagrams.  Of  the  two  hundred  and  fifty-four 
illustrations  in  the  present  volume,  only  eleven  have  been  bor- 
rowed from  other  writers,  to  whom  they  will  be  found  duly 
credited  in  the  list  of  woodcuts. 

Of  the  remaining  illustrations,  prepared  expressly  for  the  pre- 
sent work,  the  drawings  of  anatomical  structures,  crystals,  and 
microscopic  views  generally,  were  all  taken  from  nature.  The 
diagrams  were  arranged,  for  purposes  of  convenience,  in  such 
a  manner  as  to  illustrate  known  anatomical  or  physiological  ap- 
pearances, in  the  most  compact  and  intelligible  form. 

Physiological  questions  which  are  in  an  altogether  unsettled 
state,  as  well  as  purely  hypothetical  topics,  have  been  purposely 
avoided,  as  not  coming  within  the  plan  of  this  work,  nor  as  calcu- 
lated to  increase  its  usefulness. 

New  York,  January  1,  1859. 


CONTENTS. 


INTRODUCTION. 

PAGE 

Definition  of  Physiology — Its  mode  of  study — Nature  of  Vital  Phenomena — 
Division  of  the  subject  .......         17-27 


SECTION  I. 
.      NUTRITION. 

CHAPTER    I. 

PROXIMATE  PRINCIPLES  IN  GENERAL. 

Definition  of  Proximate  Principles — Mode  of  their  extraction — Manner  in  which 
they  are  associated  with  each  other — Natural  variation  in  their  relative 
quantities — Three  distinct  classes  of  proximate  principles        .  .         29-36 

CHAPTER    II. 

PROXIMATE  PRINCIPLES  OP  THE  FIRST  CLASS. 

Inorganic  Substances — Water — Chloride  of  Sodium — Chloride  of  Potassium — 
Phosphate  of  Lime — Carbonate  of  Lime — Carbonate  of  Soda — Phosphates  of 
Magnesia,  Soda,  and  Potass — Inorganic  proximate  principles  not  altered  in 
the  body — Their  discharge — Nature  of  their  function   .  .  .         37-46 

CHAPTER    III. 

PROXIMATE  PRINCIPLES  OP  THE  SECOND  CLASS. 

Starch — Percentage  of  starch  in  different  kinds  of  food — Varieties  of  this 
substance — Properties  and  reactions  of  starch — Its  conversion  into  sugar — 
Sugar — Varieties  of  sugar — Physical  and  chemical  properties — Proportion 
in  different  kinds  of  food — Fats — Varieties — Properties  and  reactions  of  fat 
— Its  crystallization — Proportion  in  different  kinds  of  food — Its  condition  in 
the  body — Internal  production  of  fat — Origin  and  destination  of  proximate 
principles  of  this  class   .......         47-62 


X  CONTENTS. 

CHAPTER    lY. 

PROXIMATE  PRINCIPLES  OF  THE  THIRD  CLASS. 

PAGE 

General  characters  of  organic  substances — Their  chemical  constitution — Hygro- 
scopic properties — Coagulation — Catalysis — Fermentation — Putrefaction — 
Fibrin — Albumen — Casein — Globuline — Pepsine — Pancreatine — Mucosine — 
Osteine  —  Cartilagine  —  Mnsculine  —  Hsematine  —  Melanine  —  Bill  verdine — 
Urosacine — Origin  and  destruction  of  proximate  principles  of  this  class      63-72 

CHAPTER    V. 

OF  FOOD. 

Importance  of  inorganic  substances  as  ingredients  of  food — Of  saccharine  and 
starchy  substances — Of  fatty  matters — Insufiiciency  of  these  substances 
when  used  alone — Effects  of  an  exclusive  non-nitrogenous  diet — Organic 
substances  also  insufficient  by  themselves — Experiments  of  Magendie  on 
exclusive  diet  of  gelatine  or  fibrin — Food  requires  to  contain  all  classes  of 
proximate  principles — Composition  of  various  kinds  of  food — Daily  quantity 
of  food  required  by  man — Digestibility  of  food — Efifect  of  cooking       .         73-82 

CHAPTER    Y  I. 

DIGESTION. 

Nature  of  digestion — Digestive  apparatus  of  fowl — Of  ox — Of  man — Mastica- 
tion— Varieties  of  teeth — Effect  of  mastication — Saliva — Its  composition — 
Daily  quantity  produced — Its  action  on  starch — Effect  of  its  suppression — 
Function  of  the  saliva — Gastric  Juice,  and  Stomach  Digestion — Structure  of 
gastric  mucous  membrane — Dr.  Beaumont's  experiments  on  St.  Martin — 
Artificial  gastric  fistulse — Composition  and  properties  of  gastric  juice — Its 
action  on  albuminoid  substances — Peristaltic  action  of  stomach — Time  re- 
quired for  digestion — Daily  quantity  of  gastric  juice — Influences  modifying 
its  secretion — Intestinal  Juices,  and  the  Digestion  of  Sugar  and  Starch — 
Follicles  of  intestine — Properties  of  intestinal  juice — Pancreatic  Juice,  and 
THE  Digestion  of  Fat — Composition  and  properties  of  pancreatic  juice — Its 
action  on  oily  matters — Successive  changes  in  intestinal  digestion      .       83-127 

CHAPTER    YII. 

ABSORPTION. 

Closed  follicles  and  villi  of  small  intestine — Peristaltic  motion — Absorption 
by  bloodvessels  and  lymphatics — Chyle — Lymph — Absorbent  system — Lac- 
teals  and  lymphatics — Absorption  of  fat — Its  accumulation  in  the  blood 
during  digestion — Its  final  decomposition  and  disappearance    ;  .     128-140 


CONTENTS.  XI 

CHAPTER    VIII. 

THE  BILE. 

PAGE 

Physical  properties  of  the  bile — Its  compositiou — Biliverdine — Cholesterin — 
Biliary  salts — Their  mode  of  extraction — Crystallization — Glyko-cholate  of 
soda — Tauro-cholate  of  soda — Biliary  salts  in  diiferent  species  of  animals 
and  in  man — Tests  for  bile — Variations  and  functions  of  bile — Daily  quan- 
tity— Time  of  its  discharge  into  intestine — Its  disappearance  from  the  ali- 
mentary canal — Its  reabsorption — Its  ultimate  decomposition  .  .     141-164 

CHAPTER    IX. 

FORMATION  OF  SUGAR  IN  THE  LIVER. 

Existence  of  sugar  in  li^rer  of  all  animals — Its  percentage — Internal  origin  of 
liver-sugar — Its  production  after  death — Glycogenic  matter  of  the  liver — Its 
properties  and  composition — Absorption  of  liver-sugar  by  hepatic  veins — 
Its  accumulation  in  the  blood  during  digestion — Its  final  decomposition  and 
disappearance     .  .  .  .  .  .  .  .     165-172 

CHAPTER   X. 

THE  SPLEEN. 

Capsule  of  Spleen — Variations  in  size  of  the  organ — Its  internal  structure — 
Malpighian  bodies  of  the  spleen — Action  of  spleen  on  the  blood — Effect  of 
its  extirpation     ........     173-177 

CHAPTER   XI. 

THE  BLOOD. 

Red  Globules  of  the  blood — Their  microscopic  characters — Structure  and  com- 
position— Variations  in  size  in  different  animals — White  Globules  of  the 
blood — Independence  of  the  two  kinds  of  blood-globules — Plasma — Its  com- 
position— Fibi'in — Albumen — Fatty  matters — Saline  ingredients — Extractive 
matters — Coagulation  of  the  Blood — Separation  of  clot  and  serum — Influ- 
ences hastening  or  retarding  coagulation — Coagulation  not  a  commencement 
of  organization — Formation  of  buflfy  coat — Entire  quantity  of  blood  in  body 

178-196 

CHAPTER    XII. 

RESPIRATION. 

Respiratory  apparatus  of  aquatic  and  air-breathing  animals — Structure  of 
lungs  in  human  subject — Respiratory  movements  of  chest — Of  glottis — 
Changes  in  the  air  during  respiration — Changes  in  the  blood — Proportions 
of  oxygen  and  carbonic  acid,  in  venous  and  arterial  blood-r— Solution  of  gases 
by  the  blood-globules — Origin  of  carbonic  acid  in  the  blood — Its  mode  of 
production — Quantity  of  carbonic  acid  exhaled  from  the  body — Variations 
according  to  age,  sex,  temperature,  &c. — Respiration  by  the  skin         .     197-217 


XU  CONTENTS. 

CHAPTER   XIII. 

ANIMAL  HEAT. 

PAGE 
Standard  temperature  of  animals — How  maintained — Production  of  heat  by- 
Vegetables — Mode  of  generation  of  animal  heat — Theory  of  combustion — 
Objections  to  this  theory — No  oxidation  in  vegetables  during  production  of 
heat — Quantities  of  oxygen  and  carbonic  acid  in  animals  do  not  correspond 
with  each  other — Production  of  animal  heat  a  local  process — Depends  on 
the  chemical  phenomena  of  nutrition    .....     218-228 

CHAPTER   XIY. 

THE  CIRCULATIOx^. 

Circulatory  apparatus  of  fish — Of  reptiles — Of  mammalians — Course  of  blood 
through  the  heart — Action  of  valves — Sounds  of  heart — Movements — Im- 
pulse— Successive  pulsations — Arterial  system — Movement  of  blood  through 
the  arteries — Arterial  pulse — Rapidity  of  arterial  circulation — The  veins — 
Causes  of  movement  of  blood  in  the  veins — Rapidity  of  venous  current — 
Capillary  circulation — Phenomena  and  causes  of  cap>illary  circulation — 
Rapidity  of  entire  circulation — Local  variations  in  different  parts        .     229-264 

CHAPTER  XV. 

SECRETION. 

Nature  of  secretion — Variations  in  activity — Mucus — Sebaceous  matter — Per- 
spiration— Tears — Milk — Secretion  of  bile — Anatomical  peculiarities  .     265-281 

CHAPTER   XYI. 

EXCRETION. 

Nature  of  excretion — Excrementitious  substances — Effect  of  their  retention 
— Urea — Its  source — Conversion  into  carbonate  of  ammonia — Daily  quan- 
tity of  urea — Creatine — Creatinine— Urate  of  soda — Urates  of  potass  and 
ammonia — General  characters  of  the  urine — Its  composition — Variations — 
Accidental  ingredients  of  the  urine — Acid  and  alkaline  fermentktions — 
Final  decomposition  of  the  urine  .....     282-304 


CONTENTS.  Xlll 

SECTION    II. 
NERVOUS    SYSTEM. 

CHAPTER    I. 

GENERAL  CHARACTER  AND  FUNCTIONS  OF  THE  NERVOUS  SYSTEM. 

PAGE 

Nature  of  the  function  performed  by  nervous  system — Two  kinds  of  nervous 
tissue — Fibres  of  white  substance — Their  minute  structure — Division  and 
inosculation  of  nerves — Gray  substance — Nervous  system  of  radiata — Of 
mollusca — Of  articulata — Of  mammalia  and  human  subject — Structure  of 
encepbalon — Connections  of  its  different  parts  ....     305-327 

CHAPTER    II. 

OF  NERVOUS  IRRITABILITY,  AND  ITS  MODE  OP  ACTION. 

Irritability  of  muscles — How  esliibited — Influences  wliich  exbaust  and  destroy 
it — Nervous  irritability — How  exhibited — Continues  after  death — Exhausted 
by  repeated  excitement — Influence  of  direct  and  inverse  electrical  currents 
— Nervous  irritability  distinct  from  muscular  irritability — Nature  of  the 
nervous  force — Its  resemblance  to  electricity — Difi'erences  between  the  two 

328-339 

CHAPTER    III. 

THE  SPINAL  CORD. 

Distinct  seat  of  sensation  and  motion  in  nervous  system — Sensibility  and 
excitability — Distinct  seat  of  sensibility  and  excitability  in  spinal  cord — 
Crossed  action  of  spinal  cord — Independent  and  associated  action  of  motor 
and  sensitive  filaments — Reflex  action  of  spinal  cord — How  manifested  dur- 
ing disease — Influence  in  health  on  sphincters,  voluntary  muscles,  urinary 
bladder,  &c.         .  .  .  .  .  .  .  .     340-356 

CHAPTER    lY. 

THE  BRAIN. 

Seat  of  sensibility  and  excitability  in  difi'erent  parts  of  the  encephalon — Olfac- 
tory ganglia — Optic  thalami — Corpora  striata — Hemispheres — Remarkable 
cases  of  injury  of  hemispheres — Efi'ect  of  their  removal — Imperfect  develop- 
ment in  idiots — Aztec  children — Theory  of  phrenology — Cerebellum — Efi"ect 
of  its  injury  or  removal — Comparative  development  in  different  classes — 
Tubercula  quadrigemina — Tuber  annulare — Medulla  oblongata — Three  kinds 
of  reflex  action  in  nervous  system         .....     357-384 


xiv  CONTENTS. 

CHAPTER    Y. 

THE  CRANIAL  NERVES. 

PAGE 

Olfactory  nerves — Optic  nerves — Auditory  nerves — Classification  of  cranial 
nerves — Motor  Nerves  of  the  Head — Motor  ocull  communis — Patheticus — 
Motor  externtis — Small  root  of  fifth  pair— Facial  nerve — Sublingual  nerve 
— Spinal  accessory — Sensitive  Nerves  of  the  Head — Fifth  pair — Its  sensi- 
bility— Effect  of  division — Influence  on  the  organ  of  sight — Glosso-pharyn- 
geal  nerve — Pneumogastric — Its  distribution — Influence  on  pharynx  and 
oesophagus — On  larynx — On  lungs — On  stomach  and  digestion  .     385-413 

CHAPTER    YI. 

SYSTEM   OF   THE  GREAT  SYMPATHETIC. 

Ganglia  of  the  great  sympathetic — Distribution  of  its  nerves — Sensibility  and 
excitability  of  sympathetic — Sluggish  action  of  this  nerve — Influence  over 
organs  of  special  sense — Elevation  of  temperature  after  division  of  sympa- 
thetic— Contraction  of  pupil  following  the  same  operation — Reflex  actions 
taking  place  through  the  great  sympathetic      ....     414-425 


SECTION    III. 
KEPRODUCTION. 

CHAPTER    I. 

ON   THE   NATURE   OF   REPRODUCTION,  AND   THE  ORIGIN  OF  PLANTS  AND 

ANIMALS. 

Nature  and  objects  of  the  function  of  reproduction — Mode  of  its  accomplish- 
ment— By  generation  from  parents — Spontaneous  generation — Mistaken  in- 
stances of  this  mode  of  generation — Production  of  infusoria— Conditions  of 
their  development — Schultze's  experiment  on  generation  of  infusoria — Pro- 
duction of  animal  and  vegetable  parasites— Encysted  entozoa — Trichina 
spiralis — Tsnia — Cysticercus— Production  of  taenia  from  cysticercus — Of 
cysticercus  from  eggs  of  taenia — Plants  and  animals  always  produced  by 
generation  from  parents  .......     427-441 

CHAPTER    II. 

ON    SEXUAL   GENERATION,  AND   THE   MODE   OF   ITS   ACCOMPLISHMENT. 

Sexual  apparatus  of  plants— Fecundation  of  the  germ — Its  development  into 
a  new  plant — Sexual  apparatus  of  animals — Ovaries  and  testicles — Uni- 
sexual and  bisexual  species — Distinctive  characters  of  the  two  sexes       442-445 


CONTENTS.  XV 

CHAPTER    III. 

ON  THE  EGG,  AND  THE  FEMALE  ORGANS  OF  GENERATION. 

PAGE 
Size  and  appearance  of  the  egg — Vitelline  membrane — Vitellus — Germinative 
vesicle — Germinative  spot — Ovaries — Graafian  Follicles — Oviducts — Female 
generative  organs  of  frog — Ovary  and  oviduct  of  fowl — Changes  in  the  egg, 
while  passing  through  the  oviduct — Complete  fowl's  egg — Uterus  and  ova- 
ries of  the  sow — Female  generative  apparatus  of  the  human  subject — Fal- 
lopian tubes— Body  of  the  uterus— Cervix  of  the  uterus  .  .     446-457 

CHAPTER    lY. 

ON   THE    SPERMATIC    FLUID,  AND   THE    MALE   ORGANS   OF   GENERATION, 

The  spermatozoa — Their  varieties  in  different  species — Their  movement — For- 
mation of  spermatozoa  in  the  testicles — Accessory  male  organs  of  generation 
— Epididymis  —  Vas  deferens  —  Vesiculae  seminales — Prostate  —  Cowper's 
glands — Function  of  spermatozoa — Physical  conditions  of  fecundation    458-464 

CHAPTER    y. 

ON   PERIODICAL   OVULATION,  AND   THE   FUNCTION   OP   MENSTRUATION. 

Periodical  Ovulation — Pre-existence  of  eggs  in  the  ovaries  of  all  animals — 
Their  increased  development  at  the  period  of  puberty — Their  successive 
ripening  and  periodical  discharge — Discharge  of  eggs  independently  of  sexual 
intercourse — Rupture  of  Graafian  follicle,  and  expulsion  of  the  egg — Pheno- 
mena of  cestruation — Menstruation — Correspondence  of  menstrual  periods 
with  periods  of  ovulation  in  the  lower  animals — Discharge  of  egg  during 
menstrual  period — Conditions  of  its  impregnation,  after  leaving  the  ovary 

465-477 

CHAPTER    Y I. 

ON   THE   CORPUS  LUTEUM   OF    MENSTRUATION   AND   PREGNANCY. 

Corpus  Luteum  of  Menstruation — Discharge  of  blood  into  the  ruptured  Graafian 
follicle — Decolorization  of  the  clot,  and  hypertrophy  of  the  membrane  of  the 
vesicle — Corpus  luteum  of  menstruation,  at  the  end  of  three  weeks — Yellow 
coloration  of  convoluted  wall — Corpus  luteum  of  menstruation  at  the  end 
of  four  weeks — Shrivelling  and  condensation  of  its  tissues — Its  condition  at 
the  end  of  nine  weeks — Its  final  atrophy  and  disappearance — Corpus  Luteum 
OF  Pregnancy — Its  continued  development  after  the  third  week — Appearance 
at  the  end  of  second  month — Of  fourth  month — At  the  termination  of  preg- 
nancy— Its  atrophy  and  disappearance  after  delivery — Distinctive  characters 
of  corpora  lutea  of  menstruation  and  pregnancy  .  .  .     478-487 


Xvi  CONTENTS. 

CHAPTER    VII. 

ON  THE  DEVELOPMENT  OF  THE  IMPREGNATED  EGG. 

PAGE 

Segmentation  of  the  vitellus — Formation  of  blastodermic  membrane. — Two 
layers  of  blastodermic  membrane — Thickening  of  external  layer — Formation 
of  primitive  trace — Dorsal  plates — Abdominal  plates — Closure  of  dorsal  and 
abdominal  plates  on  the  median  line — Formation  of  intestine — Of  mouth 
and  anus — Of  organs  of  locomotion — Continued  development  of  organs,  after 
leaving  the  egg  .......     488-497 

CHAPTER    YIII. 

THE   UMBILICAL  VESICLE. 

Separation  of  vitelline  sac  into  two  cavities — Closure  of  abdominal  walls,  and 
formation  of  umbilical  vesicle  in  fish — Mode  of  its  disappearance  after  hatch- 
ing— Umbilical  vesicle  in  human  embryo — Formation  and  growth  of  pedicle 
— Disappearance  of  umbilical  vesicle  during  embryonic  life    .  .     498-500 

CHAPTER    IX. 

AMNION   AND   ALLANTOIS — DEVELOPMENT   OF   THE   CHICK. 

Necessity  for  accessory  organs  in  the  development  of  birds  and  quadrupeds — 
Formation  of  amniotic  folds — Their  union  and  adhesion — Growth  of  allantois 
from  lower  part  of  intestine — Its  vascularity — Allantois  in  the  egg  of  the 
fowl — Respiration  of  the  egg — Absorption  of  calcareous  matter  from  the 
shell  —  Ossification  of  skeleton  —  Fracture  of  egg-shell  —  Casting  off  of 
amnion  and  allantois       .  .  .  .  .  .  .     501-509 

C  HAPTER   X. 

DEVELOPMENT  OF  THE  EGG  IN  THE  HUMAN  SPECIES — FORMATION  OF  THE 

CHORION. 

Conversion  of  allantois  into  chorion — Subsequent  changes  of  the  chorion — 
Its  villosities — Formation  of  bloodvessels  in  villosities — Action  of  villi  of 
chorion  in  providing  for  nutrition  of  foetus — Proofs  that  the  chorion  is  formed 
from  the  allantois — Partial  disappearance  of  villosities  of  chorion,  and 
changes  in  its  external  surface  .  .....     510-515 

CHAPTER    XI. 

DEVELOPMENT  OF  UTERINE  MUCOUS  MEMBRANE — FORMATION  OF  THE  DECIDUA. 

Structure  of  uterine  mucous  membrane — Uterine  tubules — Thickening  of 
uterine  mucous  membrane  after  impregnation — Decidua  vera — Entrance  of 
egg  into  uterus — Decidua  reflexa— Inclosure  of  egg  by  decidua  reflexa — 
Union  of  chorion  with  decidua — Changes  in  the  relative  development  of  dif- 
ferent portions  of  chorion  and  decidua  .....     516-522 


CONTENTS.  XVll 

CHAPTER    XII. 

THE  PLACENTA. 

PAGE 

Nourisliment  of  foetus  by  maternal  and  foetal  vessels — Arrangement  of  the 
vascular  membranes  in  different  species  of  animals — Membranes  of  foetal 
pig — Cotyledon  of  cow's  uterus — Development  of  foetal  tufts  in  liuman  pla- 
centa— Development  of  uterine  sinuses — Relation  of  foetal  and  maternal 
bloodvessels  in  tlie  placenta — Proofs  that  the  maternal  sinuses  extend 
through  the  whole  thickness  of  the  placenta — Absorption  and  exhalation 
by  the  placental  vessels  .  .....     523-531 

CHAPTER    XIII. 

DISCHARGE  OF  THE  OVUM,  AND  INVOLUTION  OF  THE  UTERUS. 

Enlargement  of  amniotic  cavity — Contact  of  amnion  and  chorion — Amniotic 
fluid — Movements  of  foetus — Union  of  decidua  vera  and  reflexa — Expulsion 
of  the  ovum  and  discharge  of  decidual  membrane — Separation  of  the  pla- 
centa— Formation  of  new  mucous  membrane  underneath  the  old  decidua — 
Fatty  degeneration  and  reconstruction  of  muscular  walls  of  uterus  532-538 

CHAPTER   XIV. 

DEVELOPMENT  OF  THE  EMBRYO — NERVOUS  SYSTEM,  ORGANS  OF  SENSE, 
SKELETON  AND  LIMBS. 

Formation  of  spinal  cord  and  cerebro-spinal  axis — Three  cerebral  vesicles — 
Hemispheres — Optic  thalami — Tubercula  quadrigemina — Cerebellum — Me- 
dulla oblongata — Eye — Pupillary  membrane — Skeleton — Chorda  dorsalis — 
Bodies  of  the  vertebrae — Laminae  and  ribs — Spina  bifida — Anterior  and  pos- 
terior extremities — Tail — Integument — Hair — Vernix  caseosa — Exfoliation 
of  epidermis        ........     539-545 

CHAPTER    XY. 

DEVELOPMENT  OP  THE  ALIMENTARY  CANAL  AND  ITS  APPENDAGES. 

Formation  of  intestine — Stomach — Duodenum — Convolutions  of  intestine — 
Large  and  small  intestine — Caput  coli  and  appendix  vermiformis — Umbi- 
lical hernia — Formation  of  urinary  bladder — Urachus — Vesico-rectal  septum 
— Perineura — Liver — Secretion   of  bile — Gastric  juice — Meconium — Glyco- 
genic function  of  liver — Diabetes  of  foetus — Pharynx  and  oesophagus — Dia- 
phragm— Diaphragmatic  hernia — Heart  and  pericardium — Ectopia  cordis — 
Development  of  the  face  ......     546-555 

1 


XVlll  CONTENTS. 


CHAPTER   XVI. 

DEVELOPMENT  OF  THE  KIDNEYS,  WOLFFIAN  BODIES,  AND  INTERNAL  ORGANS 

OF  GENERATION. 

PAGE 

Wolffian  bodies — Their  structure — First  appearance  of  kidneys — Growth  of 
kidneys,  and  atrophy  of  Wolffian  bodies — Testicles  and  ovaries — Descent  of 
the  testicles — Tunica  vaginalis  testis — Congenital  inguinal  hernia — Descent 
of  the  ovaries — Development  of  the  uterus       ....     556-565 

CHAPTER   XVII. 

DEVELOPMENT  OF  THE  CIRCULATORY  APPARATUS. 

First,  or  vitelline  circulation — Area  vasculosa — Sinus  terminalis — Vitelline 
circulation  of  fish — Arrangement  of  arteries  and  veins  in  body  of  foetus — 
Second,  or  placental  circulation — Omphalo-mesenteric  arteries  and  veins — 
Circulation  of  the  umbilical  vesicle — Of  the  allantois  and  placenta — Umbi- 
lical arteries  and  veins — Third,  or  adult  circulation — Portal  and  pulmonary 
systems — Development  of  the  arterial  system — Development  of  the  venous 
system — Changes  in  the  hepatic  circulation — Portal  vein — Umbilical  vein 
— Ductus  venosus — Changes  in  the  cardiac  circulation — Division  of  heart 
into  right  and  left  cavities — Aorta  and  pulmonary  artery — Ductus  arteriosus 
— Foramen  ovale  and  Eustachian  valve — Changes  in  circulation  at  the 
period  of  birth    .  .  .  .  .  .  .  .     566-587 

C  HAPTER    XVIII. 

DEVELOPMENT  OF  THE  BODY  AFTER  BIRTH. 

Condition  of  foetus  at  birth — Gradual  establishment  of  respiration — Inactivity 
of  the  animal  functions — Preponderance  of  reflex  actions  in  the  nervous 
system — Peculiarities  in  the  action  of  drugs  on  infant — DiflTerence  in  rela- 
tive size  of  organs,  in  infaiat  and  adult — Withering  and  separation  of  umbi- 
lical cord — Exfoliation  of  epidermis — First  and  second  sets  of  teeth — Sub- 
sequent changes  in  osseous,  muscular  and  tegumentary  systems,  and  gene- 
ral development  of  the  body       ......     588-591 


LIST  OF  ILLUSTRATIONS, 

ALL  OF  WHICH  HAVE  BEEN  PREPARED  FROM   ORIGINAL  DRAWINGS,  WITH  THE 
EXCEPTION  OF  ELEVEN,  CREDITED  TO  THEIR  AUTHORITIES. 


FIG. 

1.  Fibula  tied  iu  a  knot,  after  maceration  in  a  dilute  acid 

2.  Grains  of  potato  starcli 

3.  Starch  grains  of  Bermuda  arrowroot 

4.  Starcli  grains  of  wheat  flour 

5.  Starch  grains  of  Indian  corn 

6.  Starch  grains  from  wall  of  lateral  ventricle 

7.  Stearine 

8.  Oleaginous  principles  of  human  fat 

9.  Human  adipose  tissue 

10.  Chyle 

11.  Globules  of  cow's  milk 

12.  Cells  of  costal  cartilages 

13.  Hepatic  cells 

14.  Uriniferous  tubules  of  dog 

15.  Muscular  fibres  of  human  uterus 

16.  Alimentary  canal  of  fowl  . 

17.  Compound  stomach  of  ox 

18.  Human  alimentary  canal 

19.  Skull  of  rattlesnake 

20.  Skull  of  polar  bear 

21.  Skull  of  the  horse 

22.  Molar  tooth  of  the  horse    . 

23.  Human  teeth — upper  jaw 

24.  Buccal  and  glandular  epithelium  deposited  from  saliva 

25.  Gastric  mucous  membrane,  viewed  from  above 

26.  Gastric  mucous  membrane,  in  vertical  section 

27.  Mucous  membrane  of  pig's  stomach 

28.  Gastric  tubules  from  pig's  stomach,  pyloric  portion 

29.  Gastric  tubules  from  pig's  stomach,  cardiac  portion 

30.  Confervoid  vegetable,  growing  in  gastric  juice 

31.  Follicles  of  Lieberkiihn     . 

32.  Brunner's  duodenal  glands 

33.  Contents  of  stomach,  during  digestion  of  meat 

34.  From  duodenum  of  dog,  during  digestion  of  meat 

35.  From  middle  of  small  intestine     . 


From  Rymer  Jones 
From  Achille  Richard 


PAGE 

43 

48 

48 

49 

49 

50 

55 

56 

.  58 

58 

59 

59 

60 

60 

61 

85 

86 

87 

89 

90 

90 

90 

91 

92 

101 

101 

101 

102 

102 

108 

119 

120 

126 

126 

127 


XX 


LIST    OF    ILLUSTRATIONS. 


FIG. 

36.  From  last  quarter  of  small  intestine 

37.  One  of  the  closed  follicles  of  Peyer's  patches 

38.  Glandulse  agminatse 

39.  Extremity  of  intestinal  villus 

40.  Panizza's  experiment  on  absorption  by  bloodvessels 

41.  Chyle,  from  commencement  of  thoracic  duct 

42.  Lacteals,  thoracic  diict,  &c. 

43.  Lacteals  and  lymphatics   . 

44.  Intestinal  epithelium,  in  intervals  of  digestion 

45.  Intestinal  epithelium,  during  digestion    . 

46.  Cholesteriu  .... 

47.  Ox-bile,  crystallized 

48.  Glyko-cholate  of  soda  from  ox-bile 

49.  Glyko-cholate  and  tauro-cholate  of  soda,  from  ox-bile 

50.  Dog's  bile,  crystallized 

51.  Human  bile,  showing  resinous  matters     . 

52.  Crystalline  and  resinous  biliary  substances,  from  dog's  intestine 

53.  Duodenal  iistula    .... 

54.  Human  blood-globules 

55.  The  same,  seen  out  of  focus 

56.  The  same,  seen  within  the  focus  . 

57.  The  same,  adhering  together  in  rows 

58.  The  same,  swollen  by  addition  of  water   . 

59.  The  same,  shrivelled  by  evaporation 

60.  Blood-globules  of  frog 

61.  White  globules  of  the  blood 

62.  Coagulated  fibrin  . 

63.  Coagulated  blood  .... 

64.  Coagulated  blood,  after  separation  of  clot  and  serum 

65.  Recent  coagulum  .... 

66.  Coagulated  blood,  clot  buffed  and  cupped 

67.  Head  and  gills  of  men'obranchus  . 

68.  Lung  of  frog  .... 

69.  Human  larynx,  trachea,  bronchi,  and  lungs 

70.  Single  lobule  of  human  lung 

71.  Diagram  illustrating  the  respiratory  movements 

72.  Small  bronchial  tube 

73.  Human  larynx,  with  glottis  closed 

74.  The  same,  with  glottis  open 

75.  Human  larynx  ;  posterior  view     . 

76.  Circulation  of  fish 

77.  Circulation  of  reptiles 

78.  Circulation  of  mammalians 

79.  Human  heart,  anterior  view 

80.  Human  heart,  posterior  view 

81.  Right  auricle  and  ventricle,  tricuspid  valve  open,  arterial  valves  closed 

82.  Right  auricle  and  ventricle,  tricuspid  valve  closed,  arterial  valves  open 

83.  Course  of  blood  through  the  heart 

84.  Illustrating  production  of  valvular  sounds 

85.  Heart  of  frog,  in  relaxation 


LIST    OF    ILLUSTRATIONS. 


XXI 


FIG. 

PAGE 

86.  Heart  of  frog,  in  contraction         ..... 

241 

87.  Simple  looped  fibres         ..... 

241 

88.  Bullock's  heart,  showing  superficial  muscular  fibres 

242 

89.  Left  ventricle  of  bullock's  heart,  showing  deep  fibres     . 

242 

90.  Diagram  of  circular  fibres  of  the  heart    . 

243 

91.  Converging  fibres  of  the  apex  of  the  heart 

243 

92.  Arterial  circulation          ..... 

248 

93.  Arteiy  in  pulsation          ..... 

248 

94.  Volkmann's  apparatus    ..... 

251 

95.  The  same              ...... 

251 

96.  Vein,  with  valves  open    ..... 

253 

97.  Vein,  with  valves  closed              .... 

253 

98.  Small  artery,  with  capillary  branches     . 

255 

99.  Capillary  network            .             .             . 

256 

100.  Capillary  circulation         .... 

257 

101.  Diagram  of  the  circulation 

264 

102.  Follicles  of  a  compound  mucous  glandule           .                From  Kolliker       268 

103.  Meibomian  glands              ....                 From  Ludovic       270 

104.  Perspiratory  gland            .             .             .          From  Todd  and  Bowman      271 

105.  Glandular  structure  of  mamma  .             .             .             • 

274 

106.  Colostrum  corpuscles       .... 

275 

107.  Milk-globules       ..... 

276 

108.  Division  of  portal  vein  in  liver    . 

279 

109.  Lobule  of  liver     .             , 

280 

110.  Hepatic  cells         ..... 

281 

111.  Urea          ....          From  Lehmann  (Funke's  Atlas)       285 

112.  Creatine    ....          From  Lehmann  (Funke's  Atlas)       287 

113.  Creatinine             .             .             .          From  Lehmann  (Funke's  Atlas)       288 

114.  Urate  of  soda        ........       289 

115.  Uric  acid               ..... 

.       296 

116.  Oxalate  of  lime    .... 

.       302 

117.  Phosphate  of  magnesia  and  ammonia     . 

.       304 

118.  Nervous  filaments,  from  brain     . 

.       309 

119.  Nervous  filaments,  from  sciatic  nerve     . 

.       310 

120.  Division  of  a  nerve 

.       311 

121.  Inosculation  of  nerves     . 

.       312 

122.  Nerve  cells            .... 

.       312 

123.  Nervous  system  of  starfish 

.       313 

124.  Nervous  system  of  aplysia 

.       315 

125.  Nervous  system  of  centipede 

.       316 

126.  Cerebro-spinal  system  of  man     . 

.       319 

127.  Spinal  cord            .... 

.       320 

128.  Brain  of  alligator 

.       322 

129.  Brain  of  rabbit     .... 

.       323 

130.  Medulla  oblongata  of  human  brain 

.       324 

131.  Diagram  of  human  brain 

.       326 

132.  Experiment  showing  irritability  of  muscles 

.       329 

133.  Experiment  showing  irritability  of  nerve 

.       331 

134.  Action  of  direct  and  inverse  currents 

.       334 

135.  Diagram  of  spinal  cord  and  nerves 

.      342 

XXll 


LIST    OF    ILLUSTKATIONS. 


FIG. 

136.  Spinal  cord  in  vertical  section     . 

137.  Experiment,  showing  effect  of  poisons  on  nerves 

138.  Pigeon,  after  removal  of  the  hemispheres 

139.  Aztec  children 

140.  Brain  in  situ 

141.  Transverse  section  of  brain 

142.  Pigeon,  after  removal  of  the  cerebellum 

143.  Inferior  surface  of  brain  of  cod    . 

144.  Inferior  surface  of  brain  of  fowl  . 

145.  Course  of  optic  nerves  in  man     . 

146.  Facial  nerve 

147.  Distribution  of  fifth  nerve  upon  the  face 

148.  Pneumogastric  nerve 

149.  Great  sympathetic 

150.  Cat,  after  division  of  sympatlietic  in  the  neck 

151.  Different  kinds  of  infusoria 

152.  Experiment  on  spontaneous  generation  .  .  From  Schultze 

153.  Trichina  spiralis  . 

154.  Taenia       .... 

155.  Cysticercus,  retracted 

156.  Cysticercus,  unfolded 

157.  Blossom  of  Convolvulus  purpureus 

158.  Single  articulation  of  Taenia  crassicollis 

159.  Human  ovum 

160.  Human  ovum,  ruptured  by  pressure 

161.  Female  generative  organs  of  frog 

162.  Mature  frogs'  eggs 

163.  Female  generative  organs  of  fowl 

164.  Fowl's  egg 

165.  Uterus  and  ovaries  of  the  sow     . 

166.  Generative  organs  of  human  female 

167.  Spermatozoa 

168.  Graafian  follicle   . 

169.  Ovary  with  Graafian  follicle  ruptured 

170.  Graafian  follicle,  ruptured  and  filled  with  blood 

171.  Corpus  luteum,  three  weeks  after  menstruation 

172.  Corpus  luteum,  four  weeks  after  menstruation 

173.  Corpus  luteum,  nine  weeks  after  menstruation 

174.  Corpus  luteum  of  pregnancy,  at  end  of  second  month 

175.  Corpus  luteum  of  pregnancy,  at  end  of  fourth  month 

176.  Corpus  luteum  of  pregnancy,  at  term 

177.  Segmentation  of  the  vitellus 

178.  Impregnated  egg,  showing  embryonic  spot 

179.  Impregnated  egg,  showing  two  layers  of  blastodermic  membrane 

180.  Impregnated  egg,  farther  advanced 

181.  Frog's  egg,  at  an  early  period 

182.  Egg  of  frog,  in  process  of  development 

183.  Egg  of  frog,  farther  advanced 

184.  Tadpole,  fully  developed 

185.  Tadpole,  changing  into  frog 


LIST    OF    ILLUSTRATIONS. 


FIG. 

186.  Perfect  frog  .... 

187.  Egg  of  fish  .... 

188.  Young  fish,  with  umbilical  vesicle 

189.  Human  embryo,  with  umbilical  vesicle 

190.  Fecundated  egg,  showing  formation  of  amnion 

191.  Fecundated  egg,  showing  commencement  of  allantois 

192.  Fecundated  egg,  with  allantois  nearly  complete 

193.  Fecundated  egg,  with  allantois  fully  formed 

194.  Egg  of  fowl,  showing  area  vasculosa 

195.  Egg  of  fowl,  showing  allantois,  amnion,  &c. 

196.  Human  ovum,  showing  formation  of  chorion 

197.  Human  chorion    . 

198.  Villosity  of  chorion 

199.  Human  ovum,  at  end  of  third  month 

200.  Uterine  mucous  membrane 

201.  Uterine  tubules    . 

202.  Impregnated  uterus,  showing  formation  of  decidua 
.  203.  Impregnated  uterus,  showing  formation  of  decidua  reflexa 

204.  Impregnated  uterus,  with  decidua  reflexa  complete 

205.  Impregnated  uterus,  showing  union  of  chorion  and  decidua 

206.  Pregnant  uterus,  showing  formation  of  placenta 

207.  Foetal  pig,  with  membranes 

208.  Cotyledon  of  cow's  uterus 

209.  Foetal  tuft  of  human  placenta     . 

210.  Vertical  section  of  placenta 

211.  Human  ovum,  at  end  of  first  month 

212.  Human  ovum,  at  end  of  third  month 

213.  Gravid  human  uterus  and  contents 

214.  Muscular  fibres  of  unimpregnated  uterus 

215.  Muscular  fibres  of  human  uterus,  ten  days  after  parturition 

216.  Muscular  fibres  of  human  uterus,  three  weeks  after  parturition 

217.  Formation  of  cerebro-spinal  axis 

218.  Formation  of  cerebro-spinal  axis 

219.  Foetal  pig,  showing  brain  and  spinal  cord 

220.  Foetal  pig,  showing  brain  and  spinal  cord 

221.  Head  of  foetal  pig 

222.  Brain  of  adult  pig 

223.  Formation  of  alimentary  canal   . 

224.  Head  of  human  embryo,  at  twenty  days  .  .     From  Longet 

225.  Head  of  human  embryo,  at  end  of  first  month   .  .     From  Longet 

226.  Head  of  human  embryo,  at  end  of  second  month 

227.  Foetal  pig,  showing  Wolfiian  bodies 

228.  Foetal  pig,  showing  first  appearance  of  kidneys 

229.  Internal  organs  of  generation 

230.  Internal  organs  of  generation 

231.  Formation  of  tunica  vaginalis  testis 

232.  Congenital  inguinal  hernia 

233.  Egg  of  fowl,  showing  area  vasculosa 

234.  Egg  of  fish,  showing  vitelline  circulation 

235.  Young  embryo  and  its  vessels     . 


PAGE 

496 
498 
499 
499 
502 
503 
503 
504 
505 
506 
510 
512 
513 
514 
517 
517 
519 
519 
519 
521 
522 
524 
524 
527 
527 
532 
53a 
534 
537 
537 
538 
539 
540 
540 
541 
541 
541 
547 
553 
554 
554 
556 
558 
558 
560 
561 
562 
567 
567 
568 


XXIV 


LIST    OF    ILLUSTRATIOXS. 


FIG. 

236.  Embryo  and  its  vessels,  farther  advanced 

237.  Arterial  system,  embryonic  form 

238.  Arterial  system,  adult  form 

239.  Early  condition  of  venous  system 

240.  Venous  system,  farther  advanced 

241.  Continued  development  of  venous  system 

242.  Adult  condition  of  venous  system 

243.  Early  form  of  hepatic  circulation 

244.  Hepatic  circulation,  farther  advanced     . 

245.  Hepatic  circulation,  during  latter  part  of  foetal  life 

246.  Adult  form  of  hepatic  circulation 

247.  Foetal  heart 

248.  Foetal  heart 

249.  Foetal  heart 

250.  Foetal  heart 

251.  Heart  of  infant 

252.  Heart  of  human  foetus,  showing  Eustachian  valve 

253.  Circulation  through  the  fcetal  heart 

254.  Adult  circulation  through  the  heart 


PAGE 

569 
571 
571 
573 
574 
574 
575 
576 
577 
577 
578 
579 
579 
579 
580 
580 
582 
583 
586 


HUMAN    PHYSIOLOGY. 


INTRODUCTION. 

I.  Physiology  is  the  study  of  the  phenomena  presented  by 
organized  bodies,  animal  and  vegetable. 

These  phenomena  are  different  from  those  presented  by  inorganic 
substances.  They  require,  for  their  production,  the  existence  of 
peculiarly  formed  animal  and  vegetable  organisms,  as  well  as  the 
presence  of  various  external  conditions,  such  as  warmth,  light,  air, 
moisture,  &c. 

They  are  accordingly  more  complicated  than  the  phenomena  of 
the  inorganic  world,  and  require  for  their  study,  not  only  a  pre- 
vious acquaintance  with  the  laws  of  chemistry  and  physics,  but,  in 
addition,  a  careful  examination  of  other  characters  which  are  pecu- 
liar to  them. 

These  peculiar  phenomena,  by  which  we  so  readily  distinguish 
living  organisms  from  inanimate  substances,  are  called  Vital  j^^^eno- 
mena.,  or  the  phenomena  of  Life.  Physiology  consequently  includes 
the  study  of  all  these  phenomena,  in  whatever  order  or  species  of 
organized  body  they  may  originate. 

We  find,  however,  upon  examination,  that  there  are  certain 
general  characters  by  which  the  vital  phenomena  of  vegetables  re- 
semble each  other,  and  by  which  they  are  distinguished  from  the 
vital  phenomena  of  animals.  Thus,  vegetables  absorb  carbonic 
acid,  and  exhale  oxygen ;  animals  absorb  oxygen,  and  exhale  car- 
bonic acid.  Vegetables  nourish  themselves  by  the  absorption  of 
unorganized  liquids  and  gases,  as  water,  ammonia,  saline  solutions, 
&c. ;  animals  require  for  their  support  animal  or  vegetable  sub- 
stances as  food,  such  as  meat,  fruits,  milk,  &c.  Physiology,  theu, 
2 


18  INTEODUCTIOX. 

is  naturally  divided  into  two  parts,  viz.,  Vegetable  Physiology,  and 
Animal  Physiology. 

Again,  the  different  groups  and  species  of  animals,  while  they 
resemble  each  other  in  their  general  characters,  are  distinguished 
by  certain  minor  diff'erences,  both  of  structure  and  function,  which 
require  a  special  study.  Thus,  the  physiology  of  fishes  is  not  ex- 
actly the  same  with  that  of  reptiles,  nor  the  physiology  of  birds 
with  that  of  c[uadrupeds.  Among  the  warm-blooded  quadrupeds, 
the  carnivora  absorb  more  oxygen,  in  proportion  to  the  carbonic 
acid  exhaled,  than  the  herbivora.  Among  the  herbivorous  quad- 
rupeds, the  process  of  digestion  is  comparatively  simple  in  the 
horse,  while  it  is  complicated  in  the  ox,  and  other  ruminating  ani 
mals.  There  is,  therefore,  a  special  physiology  for  every  distinct 
species  of  animal. 

Human  Physiology  treats  of  the  vital  phenomena  of  the  human 
species.  It  is  more  practically  important  than  the  physiology  of 
the  lower  animals,  owing  to  its  connection  with  human  pathology 
and  therapeutics.  But  it  cannot  be  made  the  exclusive  subject  of 
our  study ;  for  the  special  physiology  of  the  human  body  cannot 
be  properly  understood  without  a  previous  acquaintance  with  the 
vital  phenomena  common  to  all  animals,  and  to  all  vegetables; 
besides  which,  there  are  many  phj^siological  questions  that  require 
for  their  solution  experiments  and  observations,  which  can  onl}^  be 
made  upon  the  lower  animals. 

While  the  following  treatise,  therefore,  has  for  its  principal  sub- 
ject the  study  of  Human  Physiology,  this  will  be  illustrated,  when- 
ever it  may  be  required,  by  what  we  know  in  regard  to  the  vital 
phenomena  of  vegetables  and  of  the  lower  animals. 

II.  Since  Physiology  is  the  study  of  the  active  phenomena  of 
livincr  bodies,  it  requires  a  previous  acquaintance  with  their  struc- 
ture, and  with  the  substances  of  which  they  are  composed ;  that  is, 
with  their  anatomy. 

Anatomy,  again,  requires  a  previous  acquaintance  with  inorganic 
substances;  since  some  of  these  inorganic  substances  enter  into  the 
composition  of  the  body.  Chloride  of  sodium,  for  example,  water 
and  phosphate  of  lime,  are  component  parts  of  the  animal  frame, 
and  therefore  require  to  be  studied  as  such  by  the  anatomist. 
Now  these  inorganic  substances  present  certain  active  phenomena, 
when  placed  under  the  requisite  external  conditions,  which  are 
characteristic  of  them,   and  by  which  they  may  be  recognized. 


INTRODUCTION.  19 

Thus  lime,  dissolved  in  water,  if  brought  into  contact  with  car- 
bonic acid,  alters  its  condition,  and  takes  part  in  the  formatiou  of 
an  insoluble  substance,  carbonate  of  lime,  which  is  thrown  down 
as  a  deposit.  A  knowledge  of  such  chemical  reactions  as  these  is 
necessary  to  the  anatomist,  since  it  is  by  them  that  he  is  enabled  to 
recognize  the  inorganic  substances,  forming  a  part  of  the  animal 
body. 

It  is  important  to  observe,  however,  that  a  knowledge  of  these 
reactions  is  necessary  to  the  anatomist  only  in  order  to  enable  him 
to  judge  of  the  presence  or  absence  of  the  inorganic  substances  to 
which  they  belong.  It  is  the  object  of  the  anatomist  to  make  him- 
self acquainted  with  every  constituent  part  of  the  body.  Those 
parts,  therefore,  which  cannot  be  recognized  by  their  form  and 
texture,  he  distinguishes  by  their  chemical  reactions.  But  after- 
ward, he  has  no  occasion  to  decompose  them  further,  or  to  make 
them  enter  into  new  combinations;  for  he  only  wishes  to  know 
these  substances  as  they  exist  in  the  hody,  and  not  as  they  may  exist 
under  other  conditions. 

The  unorganized  substances  which  exist  in  the  body  as  compo- 
nent parts  of  its  structure,  such  as  chloride  of  sodium,  water,  phos- 
phate of  lime,  &c.,  are  called  the  proximate  principles  of  the  body. 
Mingled  together  in  certain  proportions,  they  make  up  the  animal 
fluids,  and  associated  also  in  a  solid  form,  they  constitute  the  tissues 
and  organs,  and  in  this  way  make  up  the  entire  frame. 

Anatomy  makes  us  acquainted  with  all  these  component  parts  of 
the  body,  both  solid  and  fluid.  It  teaches  us  the  structure  of  the 
body  in  a  state  of  rest;  that  is,  just  as  it  would  be  after  life  had 
suddenly  ceased,  and  before  putrefaction  had  begun.  On  the  other 
hand.  Physiology  is  a  description  of  the  body  in  a  state  of  activity. 
It  shows  us  its  movements,  its  growth,  its  reproduction,  and  the 
chemical  changes  which  go  on  in  its  interior;  and  in  order  to  com- 
prehend these,  we  must  know,  beforehand,  its  entire  mechanical, 
textural,  and  chemical  structure. 

It  is  evident,  therefore,  that  the  description  of  the  proximate  prin- 
ciples^ or  the  chemical  substances  entering  into  the  constitution  of 
the  body,  is,  strictly  speaking,  a  part  of  Anatomy.  But  there  are 
many  reasons  why  this  study  is  more  conveniently  pursued  in  con- 
nection with  Physiology ;  for  some  of  the  proximate  principles  are 
derived  directly,  as  we  shall  hereafter  show,  from  the  external  world, 
and  some  are  formed  from  the  elements  of  the  food  in  the  process 
of  digestion ;  while  most  of  them  undergo  certain  changes  in  the 


20  IXTEODUCTION. 

interior  of  the  body,  whicli  result  in  the  formation  of  new  sub- 
stances ;  all  these  active  phenomena  belonging  necessarily  to  the 
domain  of  Physiology. 

The  description  of  the  proximate  principles  of  animals  and  vege- 
tables will  therefore  be  introduced  into  the  following  pages. 

The  description  of  the  minute  structures  of  the  bodj',  or  Micro- 
scopic Anatomy,  is  also  so  closely  connected  with  some  parts  of  Phy- 
siology as  to  make  it  convenient  to  speak  of  them  together ;  and 
this  will  accordingly  be  done,  whenever  the  nature  of  the  subject 
may  make  it  desirable. 

III.  The  study  of  Physiology,  like  that  of  all  the  other  natural 
sciences,  is  a  study  of  phenomena,  and  of  phenomena  alone.  The 
essential  nature  of  the  vital  processes,  and  their  ultimate  causes, 
are  questions  which  are  beyond  the  reach  of  the  physiologist,  and 
cannot  be  determined  by  the  means  of  investigation  which  are  at 
his  disposal. 

Consequently,  all  efforts  to  solve  them  Avill  only  serve  to  mislead 
the  investigator,  and  to  distract  his  attention  from  the  real  subject 
of  examination.  Much  time  has  been  lost,  for  example,  in  discuss- 
ing the  probable  reason  why  menstruation  returns,  in  the  human 
female,  at  the  end  of  every  four  weeks.  But  the  observation  of 
nature,  which  is  our  only  means  of  scientific  investigation,  cannot 
throw  any  light  on  this  point,  but  only  shows  us  the  fact  that  men- 
struation does  really  recur  at  the  above  periods,  together  with  the 
phenomena  which  accompany  it,  and  the  conditions  under  which  it 
is  hastened  or  retarded,  and  increased  or  diminished,  in  intensity, 
duration,  &c.  If  we  employ  ourselves,  consequently,  in  the  discus- 
sion of  the  reason  above  mentioned,  we  shall  only  become  involved 
in  a  network  of  hypothetical  surmises,  which  can  never  lead  to  any 
definite  result.  Our  time,  therefore,  will  be  much  more  profitabl}^ 
devoted  to  the  study  of  the  above  phenomena,  which  can  be  learned 
from  nature,  and  which  constitute,  afterward,  a  permanent  acquisi- 
tion. 

The  physiologist,  accordingly,  confines  himself  strictly  to  the 
study  of  the  vital  phenomena  themselves,  their  characters,  their 
frequency,  their  regularity  or  irregularity,  and  the  conditions 
under  which  they  originate. 

When  he  has  discovered  that  a  certain  phenomenon  always 
takes  place  in  the  presence  of  certain  conditions,  he  has  established 
what  is  called  a  general  principle,  or  a  Law  of  Physiology. 


INTRODUCTION.  21 

As,  for  example,  wben  lie  has  ascertained  that  sensation  and 
motion  occupy  distinct  situations  in  every  part  of  the  nervous 
system. 

This  "  Law,"  however,  it  must  be  remembered,  is  not  a  discovery 
by  itself,  nor  does  it  give  him  any  new  information,  but  is  simply 
the  expression,  in  convenient  and  comprehensive  language,  of  the 
facts  with  which  he  was  already  previously  acquainted.  It  is  very 
dangerous,  therefore,  to  make  these  laws  or  general  principles  the 
subjects  of  our  study  instead  of  the  vital  phenomena,  or  to  suppose 
that  they  have  any  value,  except  as  the  expression  of  previously 
ascertained  facts.  Such  a  misconception  would  lead  to  bad  practi- 
cal results.  For  if  we  were  to  observe  a  phenomenon  in  discord- 
ance with  a  "  law"  or  "  principle,"  we  might  be  led  to  neglect  or 
misinterpret  the  phenomenon,  in  order  to  preserve  the  law.  But 
this  would  be  manifestly  incorrect.  For  the  law  is  not  superior  to 
the  phenomenon,  but,  on  the  contrary,  depends  upon  it,  and  derives 
its  whole  authority  from  it.  Such  mistakes,  however,  have  been 
repeatedly  made  in  Physiology,  and  have  frequently  retarded  its 
advance. 

IV.  There  is  only  one  means  by  which  Physiology  can  be 
studied :  that  is,  the  observation  of  nature.  Its  phenomena  cannot 
be  reasoned  out  by  themselves,  nor  inferred,  by  logical  sequence, 
from  any  original  principles,  nor  from  any  other  set  of  phenomena 
whatever. 

In  Mathematics  and  Philosophy,  on  the  other  hand,  certain  truths 
are  taken  for  granted,  or  perceived  by  intuition,  and  the  remainder 
afterward  derived  from  them  by  a  process  of  reasoning.  But  in 
Physiology,  as  in  all  the  other  natural  sciences,  there  is  no  such 
starting  point,  and  it  is  impossible  to  judge  of  the  character  of  a 
phenomenon  until  after  it  has  been  observed.  Thus,  the  only  way 
to  learn  what  action  is  exerted  by  nitric  acid  upon  carbonate  of 
soda  is  to  put  the  two  substances  together  and  observe  the  changes 
which  take  place ;  for  there  is  nothing  in  the  general  characters  of 
these  two  substances  which  could  guide  us  in  anticipating  the  result. 

Neither  can  we  infer  the  truths  of  Physiology  from  those  of 
Anatomy,  nor  the  truths  of  one  part  of  Physiology  from  those  of 
another  part ;  but  all  must  be  ascertained  directly  and  separately 
by  observation. 

For,  although  one  department  of  natural  science  is  almost  always 
a  necessary  preliminary  to  the  study  of  another,  yet  the  facts  of  the 


22  INTEODUCTION. 

latter  can  never  he  in  the  least  degree  inferred  from  those  of  the  former^ 
hut  must  he  studied  hy  themselves. 

Thus  Chemistry  is  essential  to  Anatomy,  because  certain  sub- 
stances, as  we  have  already  shown,  belonging  to  Chemistry,  such 
as  chloride  of  sodium,  occur  as  constituents  of  the  animal  body. 
Chemistry  teaches  us  the  composition,  reactions,  mode  of  crystal- 
lization, solubility,  &c.,  of  chloride  of  sodium ;  and  if  we  did  not 
know  these,  we  could  not  extract  it,  or  recognize  it  when  extracted 
from  the  body.  But,  however  well  we  might  know  the  chemistry 
of  this  substance,  we  could  never,  on  that  account,  irfer  its  presence 
in  the  body  or  otherwise,  nor  in  what  quantities  nor  in  what  situa- 
tions it  would  present  itself.  These  facts  must  be  ascertained  for 
themselves,  by  direct  investigation,  as  a  part  of  anatomy  proper. 

So,  again,  the  structure  of  the  body  in  a  state  of  rest,  or  its  ana- 
tomy, is  to  be  first  understood;  but  its  active  phenomena  or  its 
physiology  must  then  be  ascertained  by  direct  observation  and 
experiment.  The  most  intimate  knowledge  of  the  minute  struc- 
ture of  the  muscular  and  nervous  fibres  could  not  teach  us  any- 
thing of  their  physiology.  It  is  only  by  experiment  that  we  ascer- 
tain one  of  them  to  be  contractile,  the  other  sensitive. 

Many  of  the  phenomena  of  life  are  chemical  in  their  character, 
and  it  is  requisite,  therefore,  that  the  physiologist  know  the  or- 
dinary chemical  properties  of  the  substances  composing  the  animal 
frame.  But  no  amount  of  previous  chemical  knowledge  will 
enable  him  to  foretell  the  reactions  of  any  chemical  substance  in 
the  interior  of  the  body ;  because  the  peculiar  conditions,  under 
which  it  is  there  placed,  modify  these  reactions,  as  an  elevation  or 
depression  of  temperature,  or  other  external  circumstance,  might 
modify  them  outside  the  body. 

We  must  not,  therefore,  attempt  to  deduce  the  chemical  phe- 
nomena of  physiology  from  any  previously  established  facts,  since 
these  are  no  safe  guide ;  but  must  study  them  by  themselves,  and 
depend  for  our  knowledge  of  them  upon  direct  observation  alone. 

V.  By  the  term  Vital  phenomena^  we  mean  those  phenomena  which 
are  manifested  in  the  living  body,  and  which  are  characteristic  of 
its  functions. 

Some  of  these  phenomena  are  physical  or  mechanical  in  their 
character;  as,  for  example,  the  play  of  the  articulating  surfaces 
upon  each  other,  the  balancing  of  the  spinal  column  Avith  its  ap- 
pendages, the  action  of  the  elastic  ligaments.     Nevertheless,  these 


INTRODUCTION.  23 

]>heuomena,  tbougli  strictly  physical  in  character,  are  often  entirely 
peculiar  and  different  from  those  seen  elsewhere,  because  the  me- 
chanism of  their  production  is  peculiar  in  its  details.  Thus  the 
liuman  voice  and  its  modulations  are  produced  in  the  larynx,  in 
accordance  with  the  general  physical  laws  of  sound ;  but  the 
arrangement  of  the  elastic  and  movable  vocal  chords,  with  the 
columns  of  air  above  and  below,  the  moist  and  flexible  mucous 
membrane,  and  the  contractile  muscles  outside  of  it,  are  of  such  a 
special  character,  that  the  entire  apparatus,  as  well  as  the  sounds 
produced  by  it,  is  peculiar;  and  its  action  cannot  be  properly 
compared  with  that  of  any  other  known  musical  instrument. 

In  the  same  manner,  the  movements  of  the  heart  are  so  com- 
plicated and  remarkable  that  they  cannot  be  comprehended,  even 
by  one  who  is  acquainted  with  the  anatomy  of  the  organ,  without 
a  direct  examination.  This  is  not  because  there  is  anything  essen- 
tially obscure  or  mysterious  in  their  nature,  for  they  are  purely 
mechanical  in  character;  but  because  their  conditions  are  so  pecu- 
liar, owing  to  the  tortuous  course  of  the  muscular  fibres,  their  ar- 
rangement in  interlacing  layers,  their  attachments  and  relations, 
that  their  combined  action  produces  an  effect  altogether  peculiar, 
and  one  which  is  not  similar  to  anything  outside  the  living  body. 

A  very  large  and  important  class  of  the  vital  phenomena  are 
those  of  a  chemical  character.  It  is  one  of  the  characteristics  of 
living  bodies  that  a  succession  of  chemical  actions,  combinations 
and  decompositions,  is  constantly  going  on  in  their  interior.  It  is 
one  of  the  necessary  conditions  of  the  existence  of  every  animal 
and  every  vegetable,  that  it  should  constantly  absorb  various  sub- 
stances from  without,  which  undergo  different  chemical  alterations 
i  n  its  interior,  and  are  finally  discharged  from  it  under  other  forms. 
If  these  changes  be  prevented  from  taking  place,  life  is  immediately 
extinguished.  Thus  animals  constantly  absorb,  on  the  one  hand, 
water,  oxygen,  salts,  albumen,  oil,  sugar,  &c.,  and  give  up,  on  the 
other  hand,  to  the  surrounding  media,  carbonic  acid,  water,  ammonia, 
urea,  and  the  like;  while  between  these  two  extreme  points,  of  ab- 
sorption and  exhalation,  there  take  place  a  multitude  of  different 
transformations  which  are  essential  to  the  continuance  of  life. 

Some  of  these  chemical  actions  are  the  same  with  those  which 
are  seen  outside  the  body ;  but  most  of  them  are  entirely  peculiar, 
and  do  not  take  place,  and  cannot  be  made  to  take  place,  anywhere 
else.  This,  again,  is  not  because  there  is  anything  particularly 
mysterious  or  extraordinary  in  their  nature^  but  because  the  con- 


24  INTEODUCTION. 

ditions  necessary  for  their  accomplisliment  exist  in  the  body,  and 
do  not  exist  elsewhere.  All  chemical  phenomena  are  liable  to  be 
modified  by  surrounding  conditions.  Many  reactions,  for  example, 
which  will  take  place  at  a  high  temperature,  will  not  take  place  at 
a  low  temperature,  and  vice  versa.  Some  will  take  place  in  the  light, 
but  not  in  the  dark;  others  will  take  place  in  the  dark,  but  not  in 
the  light.  If  a  hot  concentrated  solution  of  sulphate  of  soda  be 
allowed  to  cool  in  contact  with  the  atmosphere,  it  crystallizes: 
covered  with  a  film  of  oil,  it  remains  fluid.  Because  a  chemical 
reaction,  therefore,  takes  place  under  one  set  of  conditions,  we  can- 
not be  at  all  sure  that  it  will  also  take  place  under  others,  which 
are  different. 

The  chemical  conditions  of  the  living  body  are  exceedingly  com- 
plicated. In  the  animal  solids  and  fluids  there  are  many  substances 
mingled  together  in  varying  quantities,  which  modify  or  interfere 
with  each  other's  reactions.  New  substances  are  constantly  entering 
by  absorption,  and  old  ones  leaving  by  exhalation ;  while  the  circu- 
lating fluids  are  constantly  passing  from  one  part  of  the  body  to 
another,  and  coming  in  contact  with  different  organs  of  different 
texture  and  composition.  All  these  conditions  are  peculiar,  and  so 
modify  the  chemical  actions  taking  place  in  the  body,  that  they  are 
unlike  those  met  with  anywhere  else. 

If  starch  and  iodine  be  mingled  together  in  a  watery  solution, 
they  unite  with  each  other,  and  strike  a  deep  opaque  blue  color ; 
but  if  they  be  mingled  in  the  blood,  no  such  reaction  takes  place, 
because  it  is  prevented  by  the  presence  of  certain  organic  substances 
which  interfere  with  it. 

If  dead  animal  matter  be  exposed  to  warmth,  air,  and  moisture, 
it  putrefies ;  but  if  introduced  into  the  living  stomach,  even  after 
putrefaction  has  commenced,  this  process  is  arrested,  because  the 
fluids  of  the  stomach  cause  the  animal  substance  to  undergo  a 
peculiar  transformation  (digestion),  after  which  the  bloodvessels 
immediately  remove  it  by  absorption.  There  are  also  certain  sub- 
stances which  make  their  appearance  in  the  living  body,  both  of 
animals  and  vegetables,  and  which  cannot  be  formed  elsewhere ; 
such  as  fibrin,  albumen,  casein,  pneumic  acid,  the  biliary  salts,  mor 
phine,  &c.  These  substances  cannot  be  manufactured  artificially, 
simply  because  the  necessary  conditions  cannot  be  imitated.  They 
require  for  their  production  the  presence  of  a  living  organism. 

The  chemical  phenomena  of  the  living  body  are,  therefore,  not 
different  in  their  nature  from  any  other  chemical  phenomena ;  but 


INTRODUCTION.  25 

they  are  different  in  tlieir  conditions  and  in  tbeir  results,  and  are 
consequently  peculiar  and  characteristic. 

Another  set  of  vital  phenomena  are  those  whicli  are  manifested 
in  the  processes  of  reproduction  and  development.  They  are  again 
entirely  distinct  from  any  phenomena  which  are  exhibited  by 
matter  not  endowed  with  life.  An  inorganic  substance,  even  when 
it  has  a  definite  form,  as,  for  example,  a  crystal  of  fluor-spar,  has 
no  particular  relation  to  any  similar  form  which  has  preceded,  or 
any  other  which  is  to  follow  it.  On  the  other  hand,  every  animal 
and  every  vegetable  owes  its  origin  to  preceding  animals  or  vege- 
tables of  the  same  kind ;  and  the  manner  in  which  this  production 
takes  place,  and  the  different  forms  through  which  the  new  body 
successively  passes  in  the  course  of  its  development,  constitute  the 
phenomena  of  reproduction.  These  phenomena  are  mostly  de- 
pendent on  the  chemical  processes  of  nutrition  and  growth,  which 
take  place  in  a  particular  direction  and  in  a  particular  manner;  but 
their  results,  viz.,  the  production  of  a  connected  series  of  different 
forms,  constitute  a  separate  class  of  phenomena,  which  cannot  be 
explained  in  any  manner  by  the  preceding,  and  require,  therefore, 
to  be  studied  by  themselves. 

Another  set  of  vital  phenomena  are  those  which  belong  to  the 
nervous  system.  These,  like  the  processes  of  reproduction  and 
development,  depend  on  the  chemical  changes  of  nutrition  and 
growth.  That  is  to  say,  if  the  nutritive  processes  did  not  go  on  in 
a  healthy  manner,  and  keep  the  nervous  system  in  a  healthy  condi- 
tion, the  peculiar  phenomena  which,  are  characteristic  of  it  could 
not  take  place.  The  nutritive  processes  are  necessary  conditions 
of  the  nervous  phenomena.  But  there  is  no  other  connection 
between  them ;  and  the  nervous  phenomena  themselves  are  distinct 
from  all  others,  both  in  their  nature  and  in  the  mode  in  which  they 
are  to  be  studied. 

A  troublesome  confusion  might  arise  if  we  were  to  neglect  the 
distinction  that  really  exists  between  these  different  sets  of  phe- 
nomena, and  confound  them  together  under  the  expectation  of 
thereby  simplifying  our  studies.  Since  this  can  only  be  done  by 
overlooking  real  points  of  difference,  its  effect  will  merely  be  to 
introduce  erroneous  ideas  and  suggest  unfounded  similarities,  and 
will  therefore  inevitably  retard  our  progress  instead  of  advancing  it. 

It  has  been  sometimes  maintained,  for  example,  that  all  the  vital 
phenomena,  those  of  the  nervous  system  included,  are  to  be  reduced 
to  the  chemical  chansjes  of  nutrition,  and  that  these  asain  are  to  be 


26  INTRODUCTION. 

regarded  as  not  at  all  different  in  any  respect  from  the  ordinary 
chemical  changes  taking  place  outside  the  body.  This,  however, 
is  not  only  erroneous  in  theory,  but  conduces  also  to  a  vicious 
mode  of  study.  For  it  draws  away  our  attention  from  the  phe- 
nomena themselves  and  their  real  characteristics,  and  leads  us  to 
deduce  one  set  of  phenomena  from  what  we  know  of  another;  a 
method  which  we  have  already  shown  to  be  unsafe  and  pernicious. 
It  has  also  been  asserted  that  the  phenomena  of  the  nervous 
system  are  identical  with  those  of  electricity  ;  for  no  other  reason 
than  that  there  exist  between  them  certain  general  resemblances. 
But  when  we  examine  the  phenomena  in  detail,  we  find  that,  beside 
these  general  resemblances,  there  are  many  essential  points  of  dis- 
similarity, which  must  be  suppressed  and  kept  out  of  sight  in  order 
to  sustain  the  idea  of  the  assumed  identity.  This  assumption  is 
consequently  a  forced  and  unnatural  one,  and  the  simplicity  which 
it  was  intended  to  introduce  into  our  physiological  theories  is 
imaginary  and  deceptive,  and  is  attained  only  by  sacrificing  a  part 
of  those  scientific  truths,  which  are  alone  the  real  object  of  our 
study.  We  should  avoid,  therefore,  making  auy  such  unfounded 
comparisons ;  for  the  theoretical  simplicity  which  results  from  them 
does  not  compensate  for  the  loss  of  essential  scientific  details. 

VI.  The  study  of  Physiology  is  naturally  divided  into  three 
distinct  Sections : — 

The  first  of  these  includes  everything  which  relates  to  the  Nutri- 
tion of  the  body  in  its  widest  sense.  It  comprises  the  history  of 
the  proximate  principles,  their  source,  the  manner  of  their  produc- 
tion, the  proportions  in  which  they  exist  in  different  kinds  of  food 
and  drink,  the  processes  of  digestion  and  absorption,  and  the  con- 
stitution of  the  circulating  fluids;  then  the  physical  phenomena  of 
the  circulation  and  the  forces  by  which  it  is  accomplished ;  the 
changes  which  the  blood  undergoes  in  different  parts  of  the  body ; 
all  the  phenomena,  both  physical  and  chemical,  of  respiration;  those 
of  secretion  and  excretion,  and  the  character  and  destination  of  the 
secreted  and  excreted  fluids.  All  these  processes  have  reference  to 
a  common  object,  viz.,  the  preservation  of  the  internal  structure 
and  healthy  organization  of  the  individual.  With  certain  modifi- 
cations, they  take  place  in  vegetables  as  well  as  in  animals,  and  are 
consequently  known  by  the  name  of  the  vegetative  functions. 

The  Second  Section,  in  the  natural  order  of  study,  is  devoted  to 
the  phenomena  of  the  Nervous  System.     These  phenomena  are 


INTRODUCTION.  27 

Dot  exhibited  by  vegetables,  but  belong  exclusively  to  animal  or- 
ganizations. They  bring  the  animal  body  into  relation  with  the 
external  world,  and  preserve  it  from  external  dangers,  through  the 
means  of  sensation,  movement,  consciousness,  and  volition.  They 
are  more  particularly  distinguished  by  the  name  of  the  animal 
functions. 

Lastly  comes  the  study  of  the  entire  process  of  Reproduction. 
Its  phenomena,  again,  with  certain  modifications,  are  met  with  in 
both  animals  and  vegetables ;  and  might,  therefore,  with  some  pro- 
priety, be  included  under  the  head  of  vegetative  functions.  But 
their  distinguishing  peculiarity  is,  that  they  have  for  their  object 
the  production  of  new  organisms,  which  take  the  place  of  the  old 
and  remain  after  they  have  disappeared.  These  phenomena  do 
not,  therefore,  relate  to  the  preservation  of  the  individual,  but  to 
that  of  the  species;  and  any  study  which  concerns  the  species 
comes  properly  after  we  have  finished  everything  relating  to  the 
individual. 


SECTIOI(  I. 
NUTRITION. 

CHAPTER  I. 

PROXIMATE    PRINCIPLES   IN   GENERAL. 

The  study  of  Nuteition  begins  naturally  with  tliat  of  the  2^roxi- 
mate  princijjies,  or  the  substances  entering  into  the  composition  of 
the  different  parts  of  the  body,  and  the  different  kinds  of  food.  In 
examining  the  body,  the  anatomist  finds  that  it  is  composed,  first, 
of  various  parts,  which  are  easily  recognized  by  the  eye,  and  which 
occupy  distinct  situations.  In  the  case  of  the  human  body,  for 
example,  a  division  is  easily  made  of  the  entire  frame  into  the  head, 
the  neck,  the  trunk,  and  extremities.  Each  of  these  regions,  again, 
is  found,  on  examination,  to  contain  several  distinct  parts,  or 
"organs,"  which  require  to  be  separated  from  each  other  by  dissec- 
tion, and  which  are  distinguished  by  their  form,  color,  texture,  and 
consistency.  In  a  single  limb,  for  example,  every  bone  and  every 
muscle  constitutes  a  distinct  organ.  In  the  trunk,  we  have  the 
heart,  the  lungs,  the  liver,  spleen,  kidneys,  spinal  cord,  &c.,  each  of 
which  is  also  a  distinct  organ.  When  a  number  of  organs,  differing 
in  size  and  form,  but  similar  in  texture,  are  found  scattered  through- 
out the  entire  frame,  or  a  large  portion  of  it,  they  form  a  connected 
set  or  order  of  parts,  which  is  called  a  "  system."  Thus,  all  the 
muscles  taken  together  constitute  the  muscular  system;  all  the 
bones,  the  osseous  system;  all  the  arteries,  the  arterial  system. 
Several  entirely  different  organs  may  also  be  connected  with  each 
other,  so  that  their  associated  actions  may  tend  to  accomplish  a 
single  object,  and  they  then  form  an  "  apparatus."  Thus  the  heart, 
arteries,  capillaries,  and  veins,  together,  form  the  circulatory  appa- 
ratus; the  stomach,  liver,  pancreas,  intestine,  &c.,  the  digestive 
apparatus.     Every  organ,  again,  on    microscopic  examination,  is 


30  PEOXIMATE    PRIXCIPLES    IX    GEXEPvAL. 

seen  to  be  made  up  of  minute  bodies,  of  definite  size  and  figure, 
which,  are  so  small  as  to  be  invisible  to  the  naked  eye,  and  which, 
after  separation  from  each  other,  cannot  be  further  subdivided  with- 
out destroying  their  organization.  They  are,  therefore,  called  "ana- 
tomical elements."  Thus,  in  the  liver,  there  are  hepatic  cells,  capil- 
lary bloodvessels,  the  fibres  of  Glisson's  capsule,  and  the  ultimate 
filaments  of  the  hepatic  nerves.  Lastly,  two  or  more  kinds  of  ana- 
tomical elements,  interwoven  with  each  other  in  a  particular  manner, 
form  a  "tissue."  Adipose  vesicles,  with  capillaries  and  nerve  tubes, 
form  adipose  tissue.  White  fibres  and  elastic  fibres,  with  capillaries 
and  nerve  tubes,  form  areolar  tissue.  Thus  the  solid  parts  of  the 
entire  body  are  made  up  of  anatomical  elements,  tissues,  organs, 
systems,  and  apparatuses.  Every  organized  frame,  and  even  every 
apparatus,  every  organ,  and  every  tissue,  is  made  up  of  different 
parts,  variously  interwoven  and  connected  with  each  other,  and  it 
is  this  character  which  constitutes  its  organization. 

But  besides  the  above  solid  forms,  there  are  also  certain  fluids, 
which  are  constantly  present  in  various  parts  of  the  body,  and  which, 
from  their  peculiar  constitution,  are  termed  "animal  fluids."  These 
fluids  are  just  as  much  an  essential  part  of  the  body  as  the  solids. 
The  blood  and  the  lymph,  for  example,  the  pericardial  and  synovial 
fluids,  the  saliva,  which  always  exists  more  or  less  abundantly  in 
the  ducts  of  the  parotid  gland,  the  bile  in  the  biliary  ducts  and  the 
gall-bladder:  all  these  go  to  make  up  the  entire  body,  and  are  quite 
as  necessary  to  its  structure  as  the  muscles  or  the  nerves.  Now,  if 
these  fluids  be  examined,  they  are  found  to  be  made  up  of  many 
different  substances,  which  are  mingled  together  in  certain  propor- 
tions ;  these  proportions  being  constantly  maintained  at  or  about 
the  same  standard  by  the  natural  processes  of  nutrition.  Such  a 
fluid  is  termed  an  organized  fluid.  It  is  organized  by  virtue  of  the 
numerous  ingredients  which  enter  into  its  composition,  and  the 
regular  proportions  in  which  these  ingredients  are  maintained. 
Thus,  in  the  plasma  of  the  blood,  we  have  albumen,  fibrin,  water, 
chlorides,  carbonates,  phosphates,  &c.  In  the  urine,  we  find  water, 
urea,  urate  of  soda,  creatine,  creatinine,  coloring  matter,  salts,  &c. 
These  substances,  which  are  mingled  together  so  as  to  make  up,  in 
each  instance,  by  their  intimate  union,  a  homogeneous  liquid,  are 
called  the  proximate  peikciples  of  the  animal  fluid. 

In  the  solids,  however,  even  in  those  parts  which  are  apparently 
homogeneous,  there  is  the  same  mixture  of  different  ingredients. 
In  the  hard  substance  of  bone,  for  example,  there  is,  first,  water, 


TKOXIMATE    PRINCIPLES    IN    GENERAL,  31 

•\vliich  may  be  expelled  bj  evaporation;  second,  phosphate  and  car- 
bonate of  lime,  which  may  be  extracted  by  the  proper  solvents; 
third,  a  peculiar  animal  matter,  with  which  these  calcareous  salts 
are  in  union  ;  and  fourth,  various  other  saline  substances,  in  special 
proportions.  In  the  muscular  tissue,  there  is  chloride  of  potassium, 
lactic  acid,  water,  salts,  albumen,  and  an  animal  matter  termed  mus- 
culine.  The  difference  in  consistenc}^  between  the  solids  does  not, 
therefore,  indicate  any  radical  difference  in  their  constitution.  Both 
solids  and  fluids  are  equallj'  made  up  of  proximate  principles,  min- 
gled together  in  various  proportions. 

It  is  important  to  understand,  however,  exactly  what  are  proxi- 
mate principles,  and  what  are  not  such ;  for  since  these  principles 
are  extracted  from  the  animal  solids  and  fluids,  and  separated  from 
each  other  by  the  help  of  certain  chemical  manipulations,  such  as 
evaporation,  solution,  crystallization,  and  the  like,  it  might  be  sup- 
posed that  every  substance  which  could  be  extracted  from  an  organ- 
ized solid  or  fluid,  by  chemical  means,  should  be  considered  as  a 
proximate  principle.  That,  however,  is  not  the  case.  A  proximate 
principle  is  properly  defined  to  be  any  substance,  luhether  simple  or 
compound,  chemically  speaking,  ichich  exists,  under  its  own  form,  in  the 
animal  solid  or  fluid,  and  which  can  be  extracted  by  means  which  do 
not  alter  or  destroy  its  chemical  properties.  Phosphate  of  lime,  for 
example,  is  a  proximate  principle  of  bone,  but  phosphoric  acid  is 
not  so,  since  it  does  not  exist  as  such  in  the  bony  tissue,  but  is  pro- 
duced only  by  the  decomposition  of  the  calcareous  salt ;  still  less 
phosphorus,  which  is  obtained  only  by  the  decomposition  of  the 
phosphoric  acid. 

Proximate  principles  may,  in  fact,  be  said  to  exist  in  all  solids  or 
fluids  of  mixed  composition,  and  may  be  extracted  from  them  by 
the  same  means  as  in  the  case  of  the  animal  tissues  or  secretions. 
Thus,  in  a  watery  solution  of  sugar,  we  have  two  pi'oximate  princi- 
ples, viz :  first,  the  water,  and  second,  the  sugar.  The  water  may 
be  separated  by  evaporation  and  condensation,  after  which  the 
sugar  remains  behind,  in  a  crystalline  form.  These  two  substances 
have,  therefore,  been  simply  separated  from  each  other  by  the  pro- 
cess of  evaporation.  They  have  not  been  decomposed,  nor  their 
chemical  properties  altered.  On  the  other  hand,  the  oxygen  and 
hydrogen  of  the  water  were  not  proximate  principles  of  the  original 
solution,  and  did  not  exist  in  it  under  their  own  forms,  but  only  in 
a  state  of  combination;  forming,  in  this  condition,  a  fluid  substance 
(water),  endowed  with  sensible  properties  entirely  different  from 


32  PROXIMATE    PRINCIPLES    IN    GENERAL. 

theirs.  If  we  wisli  to  ascertain,  accordingly,  the  nature  and  proper- 
ties of  a  saccharine  solution,  it  will  afford  us  but  little  satisfaction  to 
extract  its  ultimate  chemical  elements;  for  its  nature  and  properties 
depend  not  so  much  on  the  presence  in  it  of  the  ultimate  elements, 
oxygen,  hydrogen,  and  carbon,  as  on  the  particular  forms  of  com- 
bination, viz.,  water  and  sugar,  under  which  they  are  present. 

It  is  very  essential,  therefore,  that  in  extracting  the  proximate 
principles  from  the  animal  body,  only  such  means  should  be  adopted 
as  will  isolate  the  substances  already  existing  in  the  tissues  and 
fluids,  without  decomposing  them,  or  altering  their  nature.  A 
neglect  of  this  rule  has  been  productive  of  much  injury  in  the  pur- 
suit of  organic  chemistry;  for  chemists,  in  subjecting  the  animal 
tissues  to  the  action  of  acids  and  alkalies,  of  prolonged  boiling,  or 
of  too  intense  heat,  have  often  obtained,  at  the  end  of  the  analj^sis, 
many  substances  which  were  erroneously  described  as  proximate 
principles,  while  they  were  only  the  remains  of  an  altered  and  dis- 
organized material.  Thus,  the  fibrous  tissues,  if  boiled  steadily  for 
thirty- six  hours,  dissolve,  for  the  most  part,  at  the  end  of  that  time, 
in  the  boiling  water ;  and  on  cooling  the  whole  solution  solidifies 
into  a  homogeneous,  jelly-like  substance,  which  has  received  the 
name  of  gelatine.  But  this  gelatine  does  not  really  exist  in.  the  body 
as  a  proximate  principle,  since  the  fibrous  tissue  which  produces  it 
is  not  at  first  soluble,  even  in  boiling  water,  and  its  ingredients 
become  altered  and  converted  into  a  gelatinous  matter  only  by  pro- 
longed ebullition.  So,  again,  an  animal  substance  containing  ace- 
tates or  lactates  of  soda  or  lime  will,  upon  incineration  in  the  open 
air,  yield  carbonates  of  the  same  bases,  the  organic  acid  having  been 
destroyed,  and  replaced  by  carbonic  acid ;  or  sulphur  and  phospho- 
rus, in  the  animal  tissue,  may  be  converted  by  the  same  means  into 
sulphuric  and  phosphoric  acids,  which,  decomposing  the  alkaline 
carbonates,  become  sulphates  and  phosphates.  In  either  case,  the 
analysis  of  the  tissues,  so  conducted,  will  be  a  deceptive  one,  and 
useless  for  all  anatomical  and  physiological  purposes,  because  its 
real  ingredients  have  been  decomposed,  and  replaced  by  others,  in 
the  process  of  manipulation. 

It  is  in  this  way  that  different  chemists,  operating  upon  the  same 
animal  solid  or  fluid,  by  following  different  plans  of  analysis,  have 
obtained  different  results;  enumerating  as  ingredients  of  the  body 
many  artificially  formed  substances,  which  are  not,  in  reality, 
proximate  principles,  thereby  introducing  much  confusion  into  phy- 
siological chemistry. 


PEOXIMATE    PRINCIPLES    IN    GENERAL.  33 

It  is  to  be  kept  constantly  in  view,  in  the  examination  of  an  ani- 
mal tissue  or  fluid,  that  the  object  of  the  operation  is  simply  the 
separation  of  its  ingredients  from  each  other,  and  not  their  decomposi- 
tion or  ultimate  analysis.  Only  the  simplest  forms  of  chemical 
manipulation  should,  therefore,  be  employed.  The  substance  to  be 
examined  should  first  be  subjected  to  evaporation,  in  order  to 
extract  and  estimate  its  water.  This  evaporation  must  be  conducted 
at  a  heat  not  above  212°  F.,  since  a  higher  temperature  would  de- 
stroy or  alter  some  of  the  animal  ingredients.  Then,  from  the  dried 
residue,  chloride  of  sodium,  alkaline  sulphates,  carbonates,  and  phos- 
phates may  be  extracted  with  water.  Coloring  matters  may  be 
separated  by  alcohol.  Oils  may  be  dissolved  out  by  ether,  &c.  &c. 
When  a  chemical  decomposition  is  unavoidable,  it  must  be  kept  in 
sight  and  afterward  corrected.  Thus  the  glyko-cholate  of  soda  of 
the  bile  is  separated  from  certain  other  ingredients  by  precipitating 
it  with  acetate  of  lead,  forming  glyko-cholate  of  lead ;  but  this  is 
afterward  decomposed,  in  its  turn,  by  carbonate  of  soda,  reproduc- 
ing the  original  glyko-cholate  of  soda.  Sometimes  it  is  impossible 
to  extract  a  proximate  principle  in  an  entirely  unaltered  form. 
Thus  the  fibrin  of  the  blood  can  be  separated  only  by  allowing  it 
to  coagulate ;  and  once  coagulated,  it  is  permanently  altered,  and 
can  no  longer  present  all  its  original  characters  of  fluidity,  &c.,  as 
it  existed  beforehand  in  the  blood.  In  such  instances  as  this,  we 
can  only  make  allowance  for  an  unavoidable  difficulty,  and  be  care- 
ful that  the  substance  suffers  no  further  alteration.  By  bearing  in 
mind  the  above  considerations,  we  may  form  a  tolerably  correct 
estimate  of  the  nature  and  quantity  of  all  of  the  proximate  princi- 
ples existing  in  the  substance  under  examination. 

The  manner  in  which  the  proximate  principles  are  associated 
together,  so  as  to  form  the  animal  tissues,  is  deserving  of  notice. 
In  every  animal  solid  and  fluid,  there  is  a  considerable  number  of 
proximate  principles,  which  are  present  in  certain  proportions,  and 
which  are  so  united  with  each  other  that  the  mixture  presents  a 
homogeneous  appearance.  But  this  union  is  of  a  complicated  cha- 
racter ;  and  the  presence  of  each  ingredient  depends,  to  a  certain 
extent,  upon  that  of  the  others.  Some  of  them,  such  as  the  alkaline 
carbonates  and  phosphates,  are  in  solution  directly  in  the  water. 
Some,  which  are  insoluble  in  water,  are  held  in  solution  by  the 
presence  of  other  soluble  substances.  Thus,  phosphate  of  lime  is 
held  in  solution  in  the  urine  by  the  bi-phosphate  of  soda.  In 
the  blood,  it  is  dissolved  by  the  albumen,  which  is  itself  fluid  by 
3 


34  PEOXIMATE    PRINCIPLES    IN    GENEEAL. 

union  with  the  water.  The  same  substance  may  be  fluid  in  one 
part  of  the  body,  and  solid  in  another  part.  Thus  in  the  blood 
and  secretions  the  water  is  fluid,  and  holds  in  solution  other  sub- 
stances, both  animal  and  mineral,  while  in  the  bones  and  cartilages 
it  is  solid — not  crystallized,  as  in  the  case  of  ice  or  of  saline  sub- 
stances which  contain  water  of  crystallization,  but  amorphous  and 
solid,  by  the  fact  of  its  intimate  union  with  the  animal  and  saline 
ingredients,  which  are  abundant  in.  quantity,  and  which  are  them- 
selves present  in  the  solid  form.  Again,  the  phosphate  of  lime  in 
the  blood  is  fluid  by  solution  in  the  albumen;  but  in  the  bones  it 
forms  a  solid  substance  with  the  animal  matter  of  the  osseous 
tissue;  and  yet  the  union  of  the  two  is  as  intimate  and.  homo- 
geneous in  the  bones  as  in  the  blood.  A  proximate  principle, 
therefore,  never  exists  alone  in  any  part  of  the  body,  but  is  always 
intimately  associated  with  a  number  of  others  by  a  kind  of  homo- 
geneous mixture  or  solution. 

Every  animal  tissue  and  fluid  contains  a  number  of  proximate 
principles  which  are  present,  as  we  have  already  mentioned,  in 
certain  characteristic  proportions.  Thus,  water  is  present  in  very 
large  quantity  in  the  perspiration  and  the  saliva,  but  in  very  small 
quantity  in  the  bones  and  teeth.  Chloride  of  sodium  is  compara- 
tively abundant  in  the  blood  and  deficient  in  the  muscles.  On  the 
other  hand,  chloride  of  potassium  is  more  abundant  in  the  muscles, 
less  so  in  the  blood.  But  these  proportions,  it  is  important  to  ob- 
serve, are  nowhere  absolute  or  invariable.  There  is  a  great  differ- 
ence in  this  respect  between  the  chemical  composition  of  an  inor- 
ganic substance  and  the  anatomical  constitution  of  an  animal  flaid. 
The  former  is  always  constant  and  definite;  the  latter  is  always 
subject  to  certain  variations.  Thus,  water  is  always  composed  of 
exactly  the  same  relative  quantities  of  oxygen  and  hydrogen ;  and 
if  these  proportions  be  altered  in  the  least,  it  thereby  ceases  to  be 
water,  and  is  converted  into  some  other  substance.  But  in  the 
urine,  the  proportions  of  water,  urea,  urate  of  soda,  phosphates,  &c., 
vary  within  certain  limits  in  different  individuals,  and  even  in  the 
same  individual,  from  one  hour  to  another.  This  variation,  which 
is  almost  constantly  taking  place,,  within  the  limits  of  health,  is 
characteristic  of  all  the  animal  solids  and  fluids ;  for  they  are  com- 
posed of  different  ingredients  which  are  supplied  by  absorption  or 
formed  in  the  interior,  and  which  are  constantly  given  up  again, 
under  the  same  or  different  forms,  to  the  surrounding  media  by  the 
unceasing  activity  of  the  vital  processes.     Every  variation,  then,  in 


PROXIMATE    PRINCIPLES    IN    GENERAL.  35 

the  general  condition  of  the  body,  as  a  whole,  is  accompanied  by 
a  corresponding  variation,  more  or  less  pronounced,  in  the  consti- 
tution of  its  different  parts.  This  constitution  is  consequently  of 
a  very  different  character  from  the  chemical  constitution  of  an 
oxide  or  a  salt.  Whenever,  therefore,  we  meet  with  the  quantita- 
tive analysis  of  an  animal  fluid,  in  which  the  relative  quantity  of 
its  different  ingredients  is  represented  in  numbers,  we  must  under- 
stand that  such  an  analysis  is  always  approximative,  and  not  abso- 
lute. 

The  proximate  principles  are  naturally  divided  into  three  differ- 
ent classes. 

The  first  of  these  classes  comprises  all  the  proximate  principles 
which  are  purely  inorganic  in  their  nature.  These  principles  are 
derived  mostly  from  the  exterior.  They  are  found  everywhere,  in 
unorganized  as  well  as  in  organized  bodies;  and  they  present  them- 
selves under  the  same  forms  and  with  the  same  properties  in  the 
interior  of  the  animal  frame  as  elsewhere.  They  are  crystallizable, 
and  have  a  definite  chemical  composition.  They  comprise  sucb 
substances  as  water,  chloride  of  sodium,  carbonate  and  phosphate 
of  lime,  &c. 

The  second  class  of  proximate  principles  is  known  as  crystal- 
lizable SUBSTANCES  OF  ORGANIC  ORIGIN.  This  is  the  name  given 
to  them  by  Robin  and  Yerdeil,'  whose  classification  of  the  proxi- 
mate principles  is  the  best  which,  has  yet  been  offered.  They  are 
crystallizable,  as  their  name  indicates,  and  have  a  definite  chemical 
composition.  They  are  said  to  be  of  "organic  origin,"  because  they 
first  make  their  appearance  in  the  interior  of  organized  bodies,  and 
are  not  found  in  external  nature  as  the  ingredients  of  inorganic 
substances.     Such  are  the  different  kinds  of  sugar,  oil,  and  starch. 

The  third  class  comprises  a  very  extensive  and  important  order 
of  proximate  principles,  which  go  by  the  name  of  the  Organic 
Substances  proper.  They  are  sometimes  known  as  "albuminoid" 
substances  or  "protein  compounds."  The  name  organic  substances 
is  given  to  them  in  consequence  of  the  striking  difference  which 
exists  between  them  and  all  the  other  ingredients  of  the  body.  The 
substances  of  the  second  class  differ  from  those  of  the  first  by  their 

'  Chimie  Anatomique  et  Physiologique.     Paris,  1853. 


36  PROXIMATE    PRINCIPLES    IN    GENERAL. 

exclusively  organic  origin,  but  they  resemble  the  latter  in  their  crys- 
tallizability  and  their  definite  chemical  composition;  in  consequence 
of  which  their  chemical  investigation  may  be  pursued  in  nearly 
the  same  manner,  and  their  chemical  changes  expressed  in  nearly 
the  same  terms.  But  the  proximate  principles  of  the  third  class 
are  in  every  respect  peculiar.  They  have  an  exclusively  organic 
origin  ;  not  being  found  except  as  ingredients  of  living  or  recently 
dead  animals  or  vegetables.  They  have  not  a  definite  chemical 
composition,  and  are  consequently  not  crystallizable;  and  the  forms 
which  they  present,  and  the  chemical  changes  which  they  undergo 
in  the  body,  are  such  as  cannot  be  expressed  by  ordinary  chemical 
phraseology.  This  class  includes  such  substances  as  albumen, 
fibrin,  casein,  &c. 


PROXIMATE    PRINCIPLES    OF    THE    FIRST    CLASS.  37 


CHAPTER    II. 

PROXIMATE    PRINCIPLES  OF   THE   FIRST   CLASS. 

The  proximate  principles  of  the  first  class,  or  those  of  an  inor- 
ganic nature,  are  very  numerous.  Their  most  prominent  characters 
have  already  been  stated.  They  are  all  crystallizable,  and  have  a 
definite  chemical  composition.  They  are  met  with  extensively  in 
the  inorganic  world,  and  form  a  large  part  of  the  crust  of  the  earth. 
They  occur  abundantly  in  the  different  kinds  of  food  and  drink ; 
and  are  necessary  ingredients  of  the  food,  since  they  are  necessary 
ingredients  of  the  animal  frame.  Some  of  them  are  found  universally 
in  all  parts  of  the  body,  others  are  met  with  only  in  particular 
regions;  but  there  are  hardly  any  which  are  not  present  at  the 
same  time  in  more  than  one  animal  solid  or  fluid.  The  following 
are  the  most  prominent  of  them,  arranged  in  the  order  of  their  re- 
spective importance. 

1.  Water. — Water  is  universally  present  in  all  the  tissues  and 
fluids  of  the  body.  It  is  abundant  in  the  blood  and  secretions, 
where  its  presence  is  indispensable  in  order  to  give  them  the  fluid- 
ity which  is  necessary  to  the  performance  of  their  functions ;  for 
it  is  by  the  blood  and  secretions  that  new  substances  are  intro- 
duced into  the  body,  and  old  ingredients  discharged.  And  it  is 
a  necessary  condition  both  of  the  introduction  and  discharge  of 
substances  naturally  solid,  that  they  assume,  for  the  time  being,  a 
fluid  form ;  water  is  therefore  an  essential  ingredient  of  the  fluids, 
for  it  holds  their  solid  materials  in  solution,  and  enables  them  to 
pass  and  repass  through  the  animal  frame. 

But  water  is  an  ingredient  also  of  the  solids.  For  if  we  take  a 
muscle  or  a  cartilage,  and  expose  it  to  a  gentle  heat  in  dry  air,  it 
loses  water  by  evaporation,  diminishes  in  size  and  weight,  and  be- 
comes dense  and  stiff.  Even  the  bones  and  teeth  lose  water  by 
evaporation  in  this  way,  though  in  smaller  quantity.  In  all  these 
solid  and  semi-solid  tissues,  the  water  which  they  contain  is  useful 


38 


PEOXIMATE    PRINCIPLES    OF    THE    FIRST    CLASS. 


37 

Bile  . 

.     880 

100 

Milk 

.     887 

130 

Pancreatic  juice 

.     900 

550 

Urine 

.     936 

750 

Lymph. 

.     960 

768 

Gastric  juice 

.     975 

789 

Perspiration 

.     986 

795 

Saliva 

.     995 

805 

bj  giving  them  the  special  consistency  which  is  characteristic  of 
them,  and  which  would  be  lost  without  it.  Thus  a  tendon,  in  its 
natural  condition,  is  white,  glistening,  and  opaque ;  and  though  very 
strong,  perfectly  flexible.  If  its  water  be  expelled  by  evaporation 
it  becomes  yellowish  in  color,  shrivelled,  semi-transparent,  inflexi- 
ble, and  totally  unfit  for  performing  its  mechanical  functions.  The 
same  thing  is  true  of  the  skin,  muscles,  cartilages,  &c. 

The  following  is  a  list,  compiled  by  Eobin  and  Yerdeil  from 
various  observers,  showing  the  proportion  of  water  per  thousand 
parts,  in  different  solids  and  fluids: — 

Quantity  of  Water  in  1,000  parts  in 
Epidermis 
Teeth 
Bones 
Cartilage 
Muscles     . 
Ligaments 
Brain 
Blood 
Synovial  fluid 

According  to  the  best  calculations,  water  constitutes,  in  the 
human  subject,  between  two-thirds  and  three-quarters  of  the  entire 
weight  of  the  body. 

The  water  which  thus  forms  a  part  of  the  animal  frame  is  derived 
from  without.  It  is  taken  in  the  different  kinds  of  drink,  and  also 
forms  an  abundant  ingredient  in  the  various  articles  of  food.  For 
no  articles  of  food  are  taken  in  an  absolutely  dry  state,  but  all 
contain  a  larger  or  smaller  quantity  of  water,  which  may  readily 
be  expelled,  by  evaporation.  The  quantity  of  water,  therefore, 
which  is  daily  taken  into  the  system,  cannot  be  ascertained  in  any 
case  by  simply  measuring  the  quantity  of  drink,  but  its  proportion 
in  the  solid  food,  taken  at  the  same  time,  must  also  be  determined 
by  experiment,  and  this  ascertained  quantity  added  to  that  which 
is  taken  in  with  the  fluids.  The  entire  quantity  of  water  so  intro- 
duced during  twenty-four  hours  varies  according  to  the  researches 
of  M.  Barral'  from  3f  to  4J  pounds. 

After  forming  a  part  of  the  animal  solids  and  fluids,  and  taking 
part  in  the  various  physical  and  chemical  processes  of  the  body,  the 
water  is  again  discharged ;  for  its  presence  in  the  body,  like  that 
of  all  the  other  proximate  principles,  is  not  permanent,  but  only 


'  In  Robin  and  Verdeil,  vol.  ii.  p.  139. 


CHLORIDE    OF    SODIUM.  39 

temporary.  After  being  taken  in  with  the  food  and  drink,  it  is 
associated  with  other  principles  in  the  fluids  and  solids,  passing 
from  the  intestine  to  the  blood  and  from  the  blood  to  the  tissues 
and  secretions.  It  afterwards  makes  its  exit  from  the  body,  from 
which  it  is  discharged  by  four  different  passages,  viz.,  in  a  liquid 
form  with  the  urine  and  the  feces,  and  in  a  gaseous  form  with  the 
breath  and  the  perspiration.  Of  all  the  water  which  is  expelled  in 
this  way,  about  48  per  cent,  is  discharged  Avith  the  urine  and  feces, ^ 
and  about  52  per  cent,  by  the  lungs  and  skin.  This  estimate,  how- 
ever, is  an  average,  calculated  from  the  observations  of  different 
authors  upon  different  individuals.  The  absolute  and  relative 
amount  of  water  discharged,  both  in  a  liquid  and  gaseous  form, 
varies  according  to  circumstances.  There  is  particularly  a  com- 
pensating action  in  this  respect  between  the  kidneys  and  the  skin, 
so  that  when  the  cutaneous  perspiration  is  very  abundant  the  urine 
is  less  so,  and  vice  versa.  The  quantity  of  water  exhaled  from  the 
lungs  varies  also  with  the  state  of  the  pulmonary  circulation,  and 
with  the  temperature  and  dryness  of  the  atmosphere.  The  water 
is  not  discharged  at  any  time  in  a  state  of  purity,  but  is  mingled  in 
the  urine  and  feces  with  saline  substances  which  it  holds  in  solution, 
and  in  the  cutaneous  and  pulmonary  exhalations  with  animal  vapors 
and  odoriferous  substances  of  various  kinds.  In  the  perspiration  it 
is  also  mingled  with  saline  substances,  which  it  leaves  behind  on 
evaporation. 

2.  Chloeide  of  Sodium. — This  substance  is  found,  like  water, 
throughout  the  different  tissues  and  fluids  of  the  body.  The  only 
exception  to  this  is  perhaps  the  enamel  of  the  teeth,  where  it  has 
not  yet  been  discovered.  Its  presence  is  important  in  the  body,  as 
regulating  the  phenomena  of  endosmosis  and  exosmosis  in  different 
parts  of  the  frame.  For  we  know  that  a  solution  of  common  salt 
passes  through  animal  membranes  much  less  readily  than  pure 
water;  and  tissues  which  have  been  desiccated  will  absorb  pure 
water  more  abundantly  than  a  saline  solution.  It  must  not  be  sup- 
posed, however,  that  the  presence  or  absence  of  chloride  of  sodium, 
or  its  varying  quantity  in  the  animal  fluids,  is  the  only  condition 
which  regulates  their  transudation  through  the  animal  membranes. 
The  manner  in  which  endosmosis  and  exosmosis  take  place  in  the 
animal  frame  depends  upon  the  relative  quantity  of  all  the  ingre- 

'  Op.  cit.,  vol.  ii.  pp.  143  and  145. 


40 


PROXIilATE    PEIXCIPLES    OF    THE    FIRST    CLASS. 


clients  of  the  fluids,  as  well  as  on  the  constitution  of  the  solids  them- 
selves; and  the  chloride  of  sodium,  as  one  ingredient  among  many, 
influences  these  phenomena  to  a  great  extent,  though  it  does  not 
regulate  them  exclusively. 

It  exerts  also  an  important  influence  on  the  solution  of  various 
other  ingredients,  with  which  it  is  associated.  Thus,  in  the  blood 
it  increases  the  solubility  of  the  albumen,  and  perhaps  also  of  the 
earthy  phosphates.  The  blood-globules,  again,  which  become  dis- 
integrated and  dissolved  in  a  solution  of  pure  albumen,  are  main- 
tained in  a  state  of  integrity  by  the  presence  of  a  small  quantity  of 
chloride  of  sodium. 

It  exists  in  the  following  proportions  in  several  of  the  solids  and 
fluids  :^ — 

QCA>'TITY  OF  ChLOEIDE  OF  SoiJirjI  IS  1.000  PAETS  !>'  THE 


Muscles  . 

2 

Bile 

3.5 

Bones 

2.5 

Blood       . 

4.5 

Milk 

1 

Mucus     . 

6 

Saliva      . 

1.5 

Aqueous  humor 

'.      11 

Urine 

3 

Vitreous  hurnor 

.      14 

In  the  blood  it  is  rather  more  abundant  than  all  the  other  saline 
ingredients  taken  together. 

Since  chloride  of  sodium  is  so  universally  present  in  all  parts  of 
the  body,  it  is  an  important  ingredient  also  of  the  food.  It  occurs, 
of  course,  in  all  animal  food,  in  the  quantities  in  which  it  naturally 
exists  in  the  corresponding  tissues;  and  in  vegetable  food  also, 
though  in  smaller  amount.  Its  proportion  in  muscular  flesh, 
however,  is  much  less  than  in  the  blood  and  other  fluids.  Conse- 
quently, it  is  not  supplied  in  sufficient  quantity  as  an  ingredient  of 
animal  and  vegetable  food,  but  is  taken  also  by  itself  as  a  condi- 
ment. There  is  no  other  substance  so  universally  used  by  all  races 
and  conditions  of  men,  as  an  addition  to  the  food,  as  chloride  of 
sodium.  This  custom  does  not  simply  depend  on  a  fancy  for  grati- 
fying the  palate,  but  is  based  upon  an  instinctive  desire  for  a  sub- 
stance which  is  necessary  to  the  proper  constitution  of  the  tissues 
and  fluids.  Even  the  herbivorous  animals  are  greedy  of  it,  and  if 
freely  supplied  with  it,  are  kept  in  a  much  better  condition  than 
when  deprived  of  its  use. 

The  importance  of  chloride  of  sodium  in  this  respect  has  been 
well  demonstrated  by  Boussingault,  in  his  experiments  on  the 
fattening  of  animals.      These  observations  were  made  upon  six 


'  Robin  and  Verdeil. 


CHLOKIDE    OF    SODIUM.  41 

bullocks,  selected,  as  nearly  as  possible,  of  the  same  age  and  vigor, 
and  subjected  to  comparative  experiment.  They  were  all  supplied 
with  an  abundance  of  nutritious  food ;  but  three  of  them  (lot  No. 
1)  received  also  a  little  over  500  grains  of  salt  each  per  day.  The 
remaining  three  (lot  No,  2)  received  no  salt,  but  in  other  respects 
were  treated  like  the  first.  The  result  of  these  experiments  is  given 
by  Boussingault  as  follows : — ' 

"Though  salt  administered  with  the  food  has  but  little  effect  in 
increasing  the  size  of  the  animal,  it  appears  to  exert  a  favorable 
influence  upon  his  qualities  and  general  aspect.  Until  the  end  of 
March  (the  experiment  began  in  October)  the  two  lots  experimented 
on  did  not  present  any  marked  difference  in  their  appearance ;  but 
in  the  course  of  the  following  April,  this  difference  became  quite 
manifest,  even  to  an  unpractised  eye.  The  lot  No.  2  had  then  been 
without  salt  for  six  months.  In  the  animals  of  both  lots  the  skin 
had  a  fine  and  substantial  texture,  easily  stretched  and  separated 
from  the  ribs;  but  the  hair,  which  was  tarnished  and  disordered  in 
the  bullocks  of  the  second  lot,  was  smooth  and  glistening  in  those 
of  the  first.  As  the  experiment  went  on,  these  characters  became 
more  marked ;  and  at  the  beginning  of  October  the  animals  of  lot 
No.  2,  after  going  without  salt  for  an  entire  year,  presented  a  rough 
and  tangled  hide,  with  patches  here  and  there  where  the  skin  was 
entirely  uncovered.  The  bullocks  of  lot  No.  1  retained,  on  the 
contrary,  the  ordinary  aspect  of  stall-fed  animals.  Their  vivacity 
and  their  frequent  attempts  at  mounting  contrasted  strongly  with 
the  dull  and  unexcitable  aspect  presented  by  the  others.  No  doubt, 
the  first  lot  would  have  commanded  a  higher  price  in  the  market 
than  the  second." 

Chloride  of  sodium  acts  also  in  a  favorable  manner  by  exciting 
the  digestive  fluids,  and  assisting  in  this  way  the  solution  of  the 
food.  For  food  which  is  tasteless,  however  nutritious  it  may  be  in 
other  respects,  is  taken  with  reluctance  and  digested  with  difficulty; 
while  the  attractive  flavor  which  is  developed  by  cooking  and  by 
the  addition  of  salt  and  other  condiments  in  proper  proportion 
excites  the  secretion  of  the  saliva  and  gastric  juice,  and  facilitates 
consequently  the  whole  process  of  digestion.  The  chloride  of 
sodium  is  then  taken  up  by  absorption  from  the  intestine,  and  is 
deposited  in  various  quantities  in  different  parts  of  the  body. 
It  is  discharged  with  the  urine,  mucus,  cutaneous  perspiration, 

'  Chimie  Agricole,  p.  271.     Paris,  1854. 


42  PEOXIMATE    PRINCIPLES    OF    THE    FIRST    CLASS, 

&c.,  in  solution  in  tlie  water  of  these  fluids.  According  to  the  esti- 
mates of  M.  Barral/  a  small  quantity  of  chloride  of  sodium  dis 
appears  in  the  body;  since  he  finds  by  accurate  comparison  that  all 
the  salt  introduced  with  the  food  is  not  to  be  found  in  the  excreted 
fluids,  but  that  about  one-fifth  of  it  remains  unaccounted  for.  This 
portion  is  supposed  to  undergo  a  double  decomposition  in  the  blood 
with  phosphate  of  potass,  forming  chloride  of  potassium  and  phos- 
phate of  soda.  By  far  the  greater  part  of  the  chloride  of  sodium, 
however,  escapes  under  its  own  form  with  the  secretions. 

3,  Chloride  of  Potassium. — This  substance  is  found  in  the 
muscles,  the  blood,  the  milk,  the  urine,  and  various  other  fluids 
and  tissues  of  the  body.  It  is  not  so  universally  present  as  chlo- 
ride of  sodium,  and  not  so  important  as  a  proximate  principle. 
In  some  parts  of  the  body  it  is  more  abundant  than  the  latter 
salt,  in  others  less  so.  Thus,  in  the  blood  there  is  more  chloride 
of  sodium  than  chloride  of  potassium,  but  in  the  muscles  there  is 
more  chloride  of  potassium  than  chloride  of  sodium.  This  sub- 
stance is  always  in  a  fluid  form,  by  its  ready  solubility  in  water, 
and  is  easily  separated  by  lixiviation,  It  is  introduced  mostly  with 
the  food,  but  is  probably  formed  partly  in  the  interior  of  the  body 
from  chloride  of  sodium  by  double  decomposition,  as  already  men- 
tioned.    It  is  discharged  with  the  mucus,  the  saliva,  and  the  urine. 

4.  Phosphate  of  Lime. — This  is  perhaps  the  most  important 
of  the  mineral  ingredients  of  the  body  next  to  chloride  of  sodium. 
It  is  met  with  universally,  in  every  tissue  and  every  fluid.  Its 
quantity,  however,  varies  very  much  in  different  parts,  as  will  be 
seen  by  the  following  list: — 

Quantity  of  Phosphate  of  Lime  in  1,000  parts  in  the 
Enamel  of  the  teeth .         .     885  Muscles      .         .         .         .2.5 

Dentine     .         .         .         .643  Blood         .         .         .         .0.3 

Bones        ....     550  Gastric  juice      .         •         •     0.4 

Cartilages  ...       40 

It  occurs  also  under  different  physical  conditions.  In  the  bones, 
teeth,  and  cartilages  it  is  solid,  and  gives  to  these  tissues  the  resist- 
ance and  solidity  which  are  characteristic  of  them.  The  calcareous 
salt  is  not,  however,  in  these  instances,  simply  deposited  mechani- 
cally in  the  substance  of  the  bone  or  cartilage  as  a  granular  powder, 
but  is  intimately  united  with  the  animal  matter  of  the  tissues,  like 

'  In  Robin  and  Verdeil,  op.  cit.,  vol.  ii.  p.  193. 


PHOSPHATE    OF    LIME. 


43 


a  coloring  matter  in  colored  glass,  so  as  to  present  a  more  ov  less 
homogeneous  appearance.  It  can,  however,  be  readily  dissolved 
out  by  maceration  in  dilute  muriatic  acid,  leaving  behind  the 
animal  substance,  which  still  retains  the  original  form  of  the  bone 
or  cartilage.  It  is  not,  therefore,  united  with  the  animal  matter  so 
as  to  lose  its  identity  and  form  a  new  chemical  substance,  as  where 
an  acid  combines  with  an  alkali  to  form  a  salt,  but  in  the  same 
manner  as  salt  unites  with  water  in  a  saline  solution,  both  sub- 
stances retaining  their  original  character  and  composition,  but  so 
intimately  associated  that  they  cannot  be  separated  by  mechanical 
means. 

In  the  blood,  phosphate  of  lime  is  in  a  liquid  form,  notwithstand- 
ing its  insolubility  in  water  and  in  alkaline  fluids,  being  held  in 
solution  by  the  albuminous  matters  of  the  circulating  fluid.  In  the 
urine,  it  is  retained  in  solution  by  the  bi-phosphate  of  soda. 

In  all  the  solid  tissues  it  is  useful  by  giving  to  them  their  proper 
consistence  and  solidity.  For  example,  in  the  enamel  of  the  teeth, 
the  hardest  tissue  of  the  body,  it  predominates  very  much  over 
the  animal  matter,  and  is  present  in  greater  abun- 
dance there  than  in  any  other  part  of  the  frame. 
In  the  dentine,  a  softer  tissue,  it  is  in  somewhat 
smaller  quantity,  and  in  the  bones  smaller  still ; 
though  in  the  bones  it  continues  to  form  more 
than  one-half  the  entire  mass  of  the  osseous  sub- 
stance. The  importance  of  phosphate  of  lime  in 
communicating  to  bones  their  natural  stiffness  and 
consistency  may  be  readily  shown  by  the  altera- 
tion which  they  suffer  from  its  removal.  If  a  long 
bone  be  macerated  in  dilute  muriatic  acid,  the 
earthy  salt,  as  already  mentioned,  is  entirely  dis- 
solved out,  when  the  bone  loses  its  rigidity,  and 
may  be  bent  or  twisted  in  any  direction  without 
breaking.  (Fig.  1.) 

Whenever  the  nutrition  of  the  bone  during  life 
is  interfered  with  from  any  pathological  cause,  so 
that  its  phosphate  of  lime  becomes  deficient  in 
amount,  a  softening  of  the  osseous  tissue  is  the 
consequence,  by  which  the  bones  yield  to  external 
pressure,  and  become  more  or  less  distorted.  (Osteo- 
malakia.) 

After  forming,  for  a  time,  a  part  of  the  tissues  and  fluids,  the 


PlBtTLA    TIED    IN    A 

KNOT,  after  macera- 
tion in  a  dilute  acid. 
(From  a  specimen  in 
tlie  museum  of  the 
College  of  Physicians 
and  Surgeons.) 


44  PEOXIMATE    PEIN'CIPLES    OP    THE    FIEST    CLASS. 

phosphate  of  lime  is  discharged  from  the  body  by  the  urine,  the 
perspiration,  mucus,  &c.  Much  the  larger  portion  is  discharged  by 
the  urine.  A  small  quantity  also  occurs  in  the  feces,  but  that  is  pro- 
bably only  the  superfluous  residue  of  what  is  taken  in  with  the  food. 

5.  Caebonate  of  Lime. — Carbonate  of  lime  is  to  be  found  in 
the  bones,  and  sometimes  in  the  urine.  The  concretions  of  the 
internal  ear  are  almost  entirely  formed  of  it.  It  very  probably 
occurs  also  in  the  blood,  teeth,  cartilages,  and  sebaceous  matter; 
but  its  presence  here  is  not  quite  certain,  since  it  may  have  been 
produced  from  the  lactate,  or  other  organic  combination,  by  the 
process  of  incineration.  In  the  bones,  it  is  in  much  smaller  quan- 
tity than  the  phosphate.  Its  solubility  in  the  blood  and  the  urine 
13  accounted  for  by  the  presence  of  free  carbonic  acid,  and  also  of 
chloride  of  potassium,  both  of  which  substances  exert  a  soluble 
action  on  carbonate  of  lime. 

6.  Caeboxate  of  Soda. — This  substance  exists  in  the  bones, 
blood,  saliva,  lymph,  and  urine.  As  it  is  readily  soluble  in  water, 
it  naturally  assumes  the  liquid  form  in  the  animal  fluids.  It  is 
important  principally  as  giving  to  the  blood  its  alkalescent  reaction, 
by  which  the  solution  of  the  albumen  is  facilitated,  and  various 
other  chemico-physiological  processes  in  the  blood  accomplished. 
The  alkalescence  of  the  blood  is,  in  fact,  necessary  to  life ;  for  it  is 
found  that,  in  the  living  animal,  if  a  mineral  acid  be  gradually 
injected  into  the  blood,  so  dilute  as  not  to  coagulate  the  albumen, 
death  takes  place  before  its  alkaline  reaction  has  been  completely 
neutralized.^ 

The  carbonate  of  soda  of  the  blood  is  partly  introduced  as  such 
with  the  food ;  but  the  greater  part  of  it  is  formed  within  the  body 
by  the  decomposition  of  other  salts,  introduced  with  certain  fruits 
and  vegetables.  These  fruits  and  vegetables,  such  as  apples, 
cherries,  grapes,  potatoes,  &c.,  contain  malates,  tartrates,  and 
citrates  of  soda  and  potass.  Now,  it  has  been  often  noticed  that, 
after  the  use  of  acescent  fruits  and  vegetables  containing  the  above 
salts,  the  urine  becomes  alkaline  in  reaction  from  the  presence  of 
the  alkaline  carbonates.  Lehmann^  found,  by  experiments  upon  his 
own  person,  that,  within  thirteen  minutes  after  taking  half  an  ounce 

'  Cl.  Bernard.  Lectures  on  tlie  Blood ;  reported  by  W.  F.  Atlee,  M.  D.  Pliila- 
delpMa,  1854,  p.  31. 

^  Physiological  Cliemistry.     Philadelpliia  ed.,  vol.  i.  p.  97. 


PHOSPHATES    OF    MAGNESIA,  SODA,  AND  POTASS,  45 

of  lactate  of  soda,  the  urine  had  an  alkaline  reaction.  He  also  ob- 
served that,  if  a  solution  of  lactate  of  soda  were  injected  into  the 
jugular  vein  of  a  dog,  the  urine  became  alkaline  at  the  end  of  five, 
or,  at  the  latest,  of  twelve  minutes.  The  conversion  of  these  salts 
into  carbonates  takes  place,  therefore,  not  in  the  intestine  but  in  the 
blood.  The  same  observer'  found  that,  in  many  persons  living  on 
a  mixed  diet,  the  urine  became  alkaline  in  two  or  three  hours  after 
swallowing  ten  grains  of  acetate  of  soda.  These  salts,  therefore, 
on  being  introduced  into  the  animal  body,  are  decomposed.  Their 
organic  acid  is  destroyed  and  replaced  by  carbonic  acid  ;  and  they 
are  then  discharged  under  the  form  of  carbonates  of  soda  and 
potass. 

7.  Carbonate  of  Potass. — -This  substance  occurs  in  very  nearly 
tbe  same  situations  as  the  last.  In  the  blood,  however,  it  is  in 
smaller  quantity.  It  is  mostly  produced,  as  above  stated,  by  the 
decomposition  of  the  malate,  tartrate,  and  citrate,  in  the  same 
manner  as  the  carbonate  of  soda.  Its  function  is  also  the  same  as 
that  of  the  soda  salt,  and  it  is  discharged  in  the  same  manner  from 
the  body. 

8,  Phosphates  of  Magnesia,  Soda,  and  Potass. — All  these 
substances  exist  universally  in  all  the  solids  and  fluids  of  the  body, 
but  in  very  small  quantity.  The  phosphates  of  soda  and  potass 
are  easily  dissolved  in  the  fluids,  owing  to  their  ready  solubility  in 
water.  The  phosphate  of  magnesia  is  held  in  solution  in  the  blood 
by  the  alkaline  chlorides  and  phosphates ;  in  the  urine,  by  the  acid 
phosphate  of  soda. 

A  peculiar  relation  exists  between  the  alkaline  phosphates  and 
carbonates  in  different  classes  of  animals.  For  while  the  fluids  of 
carnivorous  animals  contain  a  preponderance  of  phosphates,  those 
of  the  herbivora.  contain  a  preponderance  of  the  carbonates:  a 
peculiarity  readily  understood  when  we  recollect  that  muscular 
flesh  and  the  animal  tissues  generally  are  comparatively  abundant 
in  phosphates ;  while  vegetable  substances  abound  in  salts  of  the 
organic  acids,  which  give  rise,  as  already  described,  by  decomposi- 
tion in  the  blood,  to  the  alkaline  carbonates. 

The  proximate  principles  included  in  the  above  list  resemble 

'  Physiological  Chemistry,  vol.  ii.  p.  130. 


46  PROXIMATE    PRIXCIPLES    OF    THE    FIRST    CLASS. 

each  other  not  only  in  their  inorganic  origin,  their  crystallizability, 
and  their  definite  chemical  composition,  but  also  in  the  part  which 
they  take  in  the  constitution  of  the  animal  frame.  They  are 
distinguished  in  this  respect,  first,  by  being  derived  entirely  from 
without.  There  are  a  few  exceptions  to  this  rule;  as,  for  example, 
in  the  case  of  the  alkaline  carbonates,  which  partly  originate  in 
the  body  from  the  decomposition  of  malates,  tartrates,  &c.  These, 
however,  are  only  exceptions  ;  and  in  general,  the  proximate  prin- 
ciples belonging  to  the  first  class  are  introduced  with  the  food, 
and  taken  up  by  the  animal  tissues  in  precisely  the  same  form 
under  which  they  occur  in  external  nature.  The  carbonate  of  lime 
in  the  bones,  the  chloride  of  sodium  in  the  blood  and  tissues,  are 
the  same  substances  which  are  met  with  in  the  calcareous  rocks,  and 
in  solution  in  sea  water.  They  do  not  suffer  any  chemical  alteration 
in  becoming  constituent  parts  of  the  animal  frame. 

They  are  equally  exempt,  as  a  general  rule,  from  any  alteration 
while  they  remain  in  the  body,  and  during  their  passage  through 
it.  The  exceptions  to  this  rule  are  very  few ;  as,  for  example,  where 
a  small  part  of  the  chloride  of  sodium  suffers  double  decomposition 
with  phosphate  of  potass,  giving  rise  to  chloride  of  potassium  and 
phosphate  of  soda ;  or  where  the  phosphate  of  soda  itself  gives  up 
a  part  of  its  base  to  an  organic  acid  (uric),  and  is  converted  in  this 
way  into  a  bi-phosphate  of  soda. 

Nearly  the  whole  of  these  substances,  finally,  are  taken  up  un- 
changed from  the  tissues,  and  discharged  unchanged  with  the  excre- 
tions. Thus  we  find  the  phosphate  of  lime  and  the  chloride  of  so- 
dium, which  were  taken  in  with  the  food,  discharged  again  under  the 
same  form  in  the  urine.  They  do  not,  therefore,  for  the  most -part, 
participate  directly  in  the  chemical  changes  going  on  in  the  body ; 
but  only  serve  by  their  presence  to  enable  those  changes-  to  be 
accomplished  in  the  other  ingredients  of  the  animal  frame,  which 
are  necessary  to  the  process  of  nutrition. 


PROXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS,         47 


CHAPTER   III. 

PROXIMATE  PRINCIPLES  OF  THE  SECOND  CLASS. 

The  proximate  principles  belonging  to  tlie  second  class  are 
divided  into  three  principal  groups,  viz. :  starch,  sugar,  and  oil. 
Thej  are  distinguished,  in  the  first  place,  bj  their  organic  origin. 
Unlike  the  principles  of  the  first  class,  they  do  not  exist  in 
external  nature,  but  are  only  found  as  ingredients  of  organized 
bodies.  They  exist  both  in  animals  and  in  vegetables,  though  in 
somewhat  different  proportions.  All  the  substances  belonging  to 
this  class  have  a  definite  chemical  composition ;  and  are  further 
distinguished  by  the  fact  that  they  are  composed  of  oxygen,  hydro- 
gen, and  carbon  alone,  without  nitrogen,  whence  they  are  sometimes 
called  the  "  non-nitrogenous"  substances. 

1.  Starch  (C^JI^fi^^).  The  first  of  these  substances  seems  to 
form  an  exception  to  the  general  rule  in  a  very  important  particular, 
viz.,  that  it  is  not  crystallizable.  Still,  since  it  so  closely  resembles 
the  rest  in  all  its  general  properties,  and  since  it  is  easily  converti- 
ble into  SQgar,  which  is  itself  crystallizable,  it  is  naturally  included 
in  the  second  class  of  proximate  principles.  Though  not  crystal- 
lizable, furthermore,  it  still  does  assume  a  distinct  form,  by  which 
it  differs  from  substances  that  are  altogether  amorphous. 

Starch  occurs  in  some  part  or  other  of  almost  all  the  flowering 
plants.  It  is  very  abundant  in  corn,  wheat,  rye,  oats,  and  rice,  in 
the  parenchyma  of  the  potato,  in  peas  and  beans,  and  in  most  vege- 
table substances  used  as  food.  It  constitutes  almost  entirely  the 
different  preparations  known  as  sago,  tapioca,  arrowroot,  &c.,  which 
are  nothing  more  than  varieties  of  starch,  extracted  from  different 
species  of  plants. 

The  following  is  a  list  showing  the  percentage  of  starch  occurring 
in  different  kinds  of  food  : — ^ 

'  Pereira  on  Food  and  Diet,  p.  39.     New  York,  1843. 


48 


PKOXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 


Quantity  of  Starch 

IN  100  PARTS  IN 

85.07 

Wheat  flour 

56.50 

80.92 

Iceland  moss 

44.60 

67.18 

Kidney  bean 

35.94 

61.07 

Peas    . 

32.45 

59.00 

Potato 

15.70 

Rice    . 
Maize 

Barley  meal 
Rye  meal  . 
Oat  meal     . 


When  purified  from  foreign  substances,  starch  is  a  white,  liglit 
powder,  which  gives  rise  to  a  peculiar  crackling  sensation  when 

rubbed  between  the  fingers. 
■^"S-  ^-  It  is  not  amorphous,  as  we 

have  already  stated,  but  is 
composed  of  solid  granules, 
which,  while  they  have  a 
general  resemblance  to  each 
other,  differ  somewhat  in  va- 
rious particulars.  The  starch 
grains  of  the  potato  (Fig.  2), 
vary  considerably  in  size. 
The  smallest  have  a  diameter 
of  lohoo,  the  largest  ^^o  of 
an  inch.  They  are  irregu- 
larly pear-shaped  inform,  and 
are  marked  by  concentric  la- 
minse,  asifthematter  of  which 
they  are  composed  had  been  deposited  in  successive  layers.  At  one 
point  on  the  surface  of  every  starch  grain,  there  is  a  minute  pore  or 

depression,  called  the  hilus, 


Grains  of  Potato  Starch. 


Fig.  3. 


Starch  Grains  of  Bermcda  Arrowroot. 


around  which  the  circular 
markings  are  arranged  in  a 
concentric  form. 

The  starch  granules  of 
arrowroot  (Fig.  3)  are  gene- 
rally smaller,  and  more  uni- 
form in  size  than  those  of 
the  potato.  They  vary  from 
2o'oo  to  5-^0  of  an  inch  in 
diameter.  They  are  elongated 
and  cylindrical  in  form,  and 
the  concentric  markings  are 
less  distinct  than  in  the  pre- 
ceding  variety.     The   hilus 


STARCH. 


49 


Starch  Grains  op  Wheat  Flour. 


bas  here  sometimes  the  form  of  a  circular  pore,  and  sometimes  that 
of  a  transverse  fissure  or  slit. 

The  grains  of  wheat  starch  (Fig.  4)  are  still  smaller  than  those 
t)f  arrowroot.  They  vary 
from  TOO 00  to  ^lo  of  an  inch 
in  diameter.  They  are 
nearly  circular  in  form,  with 
a  round  or  transverse  hilus, 
but  without  any  distinct 
appearance  of  lamination. 
Many  of  them  are  flattened 
or  compressed  laterally,  so 
that  they  present  a  broad 
surface  in  one  position,  and 
a  narrow  edge  when  viewed 
in  the  opposite  direction. 

The  starch  grains  of  In- 
dian corn  (Fig.  5),  are  of 
nearly  the  same  size  with 
those  of  wheat  flour.  They  are  somewhat  more  irregular  and 
angular  in  shape ;  and  are  often  marked  with  crossed  or  radiating 
lines,  as  if  from  partial  fracture. 

Starch  is  also  an  ingre- 
dient of  the  animal  body. 
It  was  first  observed  by 
Purkinje,  and  afterward  by 
Koiliker, '  that  certain  bodies 
are  to  be  found  in  the  interior 
of  the  brain,  about  the  lateral 
ventricles,  in  the  fornix, 
septum  lucidum,  and  other 
parts  which  present  a  cer- 
tain resemblance  to  starch 
grains,  and  which  have  there- 
fore been  called  "corpora 
amylacea."  Subsequently 
Virchow^  corroborated  the 
above  observations,  and  ascertained  the  corpora  amylacea  to  be 

'  Handbuch  der  Gewebelehre,  Leipzig,  1852,  p.  311. 
*  In  American  Journal  Med.  Sci.,  April,  1854,  p.  466. 


Starch  Grains  of  Indian  Corn. 


50 


PROXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 


Starch  Grains  from  Wall  of  Lateral  Ventricle  ; 
from  a  woman  aged  35. 


really  substances  of  a  starchy  nature ;  since  they  exhibit  the  usual 
chemical  reactions  of  vegetable  starch. 

The  starch  granules  of  the  human  brain  (Fig.  6),  are  transparent 

and  colorless,  like  those  from 
plants.  They  refract  the  light 
strongly,  and  vary  in  size 
from  4^Vu  to  yyVo  of  an 
inch.  Their  average  is  ygViy 
of  an  inch.  They  are  some- 
times rounded  or  oval,  and 
sometimes  angular  in  shape. 
They  resemble  considerably 
in  appearance  the  starch 
granules  of  Indian  corn.  The 
largest  of  them  present  a 
very  faint  concentric  lamina- 
tion, but  the  greater  number 
are  destitute  of  any  such 
appearance.  They  have 
nearly  always  a  distinct  hilus,  which  is  sometimes  circular  and 
sometimes  slit-shaped.  They  are  also  often  marked  with  delicate 
radiating  lines  and  shadows.  On  the  addition  of  iodine,  they  become 
colored,  first  purple,  afterward  of  a  deep  blue.  They  are  less  firm 
in  consistency  than  vegetable  starch  grains,  and  can  be  more  readily 
disintegrated  by  pressing  or  rubbing  them  upon  the  glass. 

Starch,  derived  from  all  these  different  sources,  has,  so  far  as  known, 
the  same  chemical  composition,  and  may  be  recognized  by  the  same 
tests.  It  is  insoluble  in  cold  water,  but  in  boiling  water  its  granules 
first  swell,  become  gelatinous  and  opaline,  then  fuse  together,  and 
finally  liquefy  altogether,  provided  a  sufficient  quantity  of  water  be 
present.  After  that,  they  cannot  be  made  to  resume  their  original 
form,  but  on  cooling  and  drying  merely  solidify  into  a  homogeneous 
mass  or  paste,  more  or  less  consistent,  according  to  the  quantity  of 
water  which  remains  in  union  witb  it.  The  starch  is  then  said  to 
be  amorphous  or  "hydrated."  By  this  process  it  is  not  essentially 
altered  in  its  chemical  properties,  but  only  in  its  physical  condition. 
Whether  in  granules,  or  in  solution,  or  in  an  amorphous  and 
hydrated  state,  it  strikes  a  deep  blue  color  on  the  addition  of  free 
iodine. 

Starch  may  be  converted  into  sugar  by  three  different  methods. 
First,  by  boiling  with  a  dilute  acid.     If  starch  be  boiled  with  dilute 


SUGAR.  51 

nitric,  sulphuric,  or  muriatic  acid  during  thirty-six  hours,  it  first 
changes  its  opalescent  appearance,  and  becomes  colorless  atid  trans- 
parent; losing  at  the  same  time  its  power  of  striking  a  blue  color 
with  iodine.  After  a  time,  it  begins  to  acquire  a  sweet  taste,  and 
is  finally  altogether  converted  into  a  peculiar  species  of  sugar. 

Secondly,  by  contact  with  certain  animal  and  vegetable  sub- 
stances. Thus,  boiled  starch,  mixed  with  human  saliva  and  kept 
at  the  temperature  of  100°  F.,  is  converted  in  a  few  minutes  into 
sugar. 

Thirdly,  by  the  processes  of  nutrition  and  digestion  in  animals 
and  vegetables.  A  large  part  of  the  starch  stored  up  in  seeds  and 
other  vegetable  tissues  is,  at  some  period  or  other  of  the  growth  of 
the  plant,  converted  into  sugar  by  the  molecular  changes  going  on 
in  the  vegetable  fabric.  It  is  in  this  way,  so  far  as  we  know,  that 
all  the  sugar  derived  from  vegetable  sources  has  its  origin. 

Starch,  as  a  proximate  principle,  is  more  especially  important  as 
entering  largely  into  the  composition  of  many  kinds  of  vegetable 
food.  With  these  it  is  introduced  into  the  alimentary  canal,  and 
there,  during  the  process  of  digestion,  is  converted  into  sugar. 
Consequently,  it  does  not  appear  in  the  blood,  nor  in  any  of  the 
secreted  fluids. 

2.  Sugar, — This  group  of  proximate  principles  includes  a  con- 
siderable number  of  substances,  which  differ  in  certain  minor 
details,  while  they  resemble  each  other  in  the  following  particulars: 
They  are  readily  soluble  in  water,  and  crystallize  more  or  less 
perfectly  on  evaporation ;  they  have  a  distinct  sweet  taste ;  and 
finally,  by  the  process  of  fermentation,  they  are  converted  into 
alcohol  and  carbonic  acid. 

These  substances  are  derived  from  both  animal  and  vegetable 
sources.  Those  varieties  of  sugar  which  are  most  familiar  to  us 
are  the  following  six,  three  of  which  are  of  vegetable  and  three  of 
animal  origin. 

fCane  sugar,  r  Milk  sugar, 

^  Animal        ^ . 
Grape  sugar,  <  Liver  sugar, 

Sugar  of  starch.  °  V  Sugar  of  honey. 

The  cane  and  grape  sugars  are  held  in  solution  in  the  juices  of 
the  plants  from  which  they  derive  their  name.  Sugar  of  starch,  or 
glucose^  is  produced  by  boiling  starch  for  a  long  time  with  a  dilute 
acid.  Liver  sugar  and  the  sugar  of  milk  are  produced  in  the 
tissues  of  the  liver  and  the  mammary  gland,  and  the  sugar  oi 


52         PROXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 

honey  is  prepared  in  some  way  by  the  bee  from  materials  of  vege- 
table origin. 

These  varieties  cliflfer  but  little  in  their  ultimate  chemical  compo- 
sition. The  following  formulae  have  been  established  for  three  of 
them. 

Cane  sugar     ......=  C24H220^ 

Milk  siigar =  Cj^Hj^Oj^ 

Glucose =  C^jH28023 

Cane  sugar  is  sweeter  than  most  of  the  other  varieties,  and  more 
soluble  in  water.  Some  sugars,  such  as  liver  sugar  and  sugar  of 
honey,  crystallize  only  with  great  difficulty;  but  this  is  probably 
owing  to  their  being  mingled  with  other  substances,  from  which  it 
is  difficult  to  separate  them  completely.  If  they  could  be  obtained 
in  a  state  of  purity,  they  would  doubtless  crystallize  as  perfectly  as 
cane  sugar.  The  different  sugars  vary  also  in  the  readiness  with 
which  they  undergo  fermentation.  Some  of  them,  as  grape  sugar 
and  liver  sugar,  enter  into  fermentation  very  promptly ;  others,  such 
as  milk  and  cane  sugar,  with  considerable  difficulty. 

The  above  are  not  to  be  regarded  as  the  only  varieties  of  sugar 
existing  in  nature.  On  the  contrary,  it  is  probable  that  nearly 
every  different  species  of  animal  and  vegetable  produces  a  distinct 
kind  of  sugar,  differing  slightly  from  the  rest  in  its  degree  of  sweet- 
ness, its  solubility,  its  crystallization,  its  aptitude  for  fermentation, 
and  perhaps  in  its  elementary  composition.  Nevertheless,  there  is 
so  close  a  resemblance  between  them  that  they  are  all  properly 
regarded  as  belonging  to  a  single  group. 

The  test  most  commonly  employed  for  detecting  the  presence 
of  suffar  is  that  known  as  Trommer's  test.  It  depends  upon  the  fact 
that  the  saccharine  substances  have  the  power  of  reducing  the 
persalts  of  copper  when  heated  with  them  in  an  alkaline  solution. 
The  test  is  applied  in  the  following  manner :  A  very  small  quantity 
of  sulphate  of  copper  in  solution  should  be  added  to  the  suspected 
liquid,  and  the  mixture  then  rendered  distinctly  alkaline  by  the 
addition  of  caustic  potass.  The  whole  solution  then  takes  a  deep 
blue  color.  On  boiling  the  mixture,  if  sugar  be  present,  the 
insoluble  suboxide  of  copper  is  thrown  down  as  an  opaque  red, 
yellow,  or  orange  colored  deposit ;  otherwise  no  change  of  color 
takes  place. 

This  test  requires  some  precautions  in  its  application.  In  the 
first  place,  it  is  hot  applicable  to  all  varieties  of  sugar.  Cane 
sugar,  for  example,  when  pure,  has  no  power  of  reducing  the  salts 


SUGAR.  53 

of  copper,  even  when  present  in  large  quantity.  Maple  sugar, 
also,  which  resembles  cane  sugar  in  some  other  respects,  reduces 
the  copper,  in  Trommer's  test,  but  slowly  and  imperfectly.  Beet- 
root sugar,  according  to  Bernard,  presents  the  same  peculiarity.  If 
these  sugars,  however,  be  boiled  for  two  or  three  minutes  with  a 
trace  of  sulphuric  acid,  they  become  converted  into  glucose,  and 
acquire  the  power  of  reducing  the  salts  of  copper.  Milli  sugar, 
liver  sugar,  and  sugar  of  honey,  as  well  as  grape  sugar  and  glucose 
all  act  promptly  and  perfectly  with  Trommer's  test  in  their  natural 
condition. 

Secondly,  care  must  be  taken  to  add  to  the  suspected  liquid  only 
a  small  quantity  of  sulphate  of  copper,  just  sufficient  to  give  to  the 
whole  a  distinct  blue  tinge,  after  the  addition  of  the  alkali.  If  a 
larger  quantity  of  the  copper  salt  be  used,  the  sugar  in  solution 
may  not  be  sufficient  to  reduce  the  whole  of  it ;  and  that  which 
remains  as  a  blue  sulphate  will  mask  the  yellow  color  of  the  sub- 
oxide thrown  down  as  a  deposit.  By  a  little  care,  however,  in 
managing  the  test,  this  source  of  error  may  be  readily  avoided. 

Thirdly,  there  are  some  albuminous  substances  which  have  the 
power  of  interfering  with  Trommer's  test,  and  prevent  the  reduc- 
tion of  the  copper,  even  when  sugar  is  present.  Certain  animal 
matters,  to  be  more  particularly  described  hereafter,  which  are 
liable  to  be  held  in  solution  in  the  gastric  juice,  have  this  effect. 
This  source  of  error  may  be  avoided,  and  the  substances  in  ques- 
tion eliminated  when  present,  by  treating  the  suspected  fluid  with 
animal  charcoal,  or  by  evaporating  and  extracting  it  with  alcohol 
before  the  application  of  the  test. 

A  less  convenient  but  somewhat  more  certain  test  for  sugar  is 
that  o^  fermentation.  The'  saccharine  fluid  is  mixed  with  a  little 
yeast,  and  kept  at  a  temperature  of  70°  to  100°  F.  until  the  fer- 
menting process  is  completed.  By  this  process,  as  already  men-J 
tioned,  the  sugar  is  converted  into  alcohol  and  carbonic  acid.  The 
gas,  which  is  given  off  in  minute  bubbles  during  fermentation, 
should  be  collected  and  examined.  The  remaining  fluid  is  purified 
by  distillation  and  also  subjected  to  examination.  If  the  gas  be 
found  to  be  carbonic  acid,  and  the  remaining  fluid  contain  alcohol, 
there  can  be  no  doubt  that  sugar  was  present  at  the  commencement 
of  the  operation. 

The  following  list  shows  the  percentage  of  sugar  in  various 
articles  of  food.' 

'  Pereira,  op.  cit.,  p.  55. 


54 


PROXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 


Quantity  of  Sugar  in  100  parts  in 


Figs        . 

62.50 

Wheat  flour 

4.20  to  8.48 

Cherries 

18.12 

Rye  meal    . 

3.28 

Peaches 

16.48 

Indian  meal 

1.45 

Tamarinds 

12.50 

Peas    . 

2.00 

Pears 

11.52 

Cow's  milk 

4.77 

Beets 

9.00 

Ass's  milk 

6.08 

Sweet  almonds 

6.00 

Human  milk 

6.50 

Barley  meal  . 

5.21 

Beside  the  sugar,  therefore,  which  is  taken  into  the  alimentary 
canal  in  a  pure  form,  a  large  quantity  is  also  introduced  as  an  in- 
gredient of  the  sweet-flavored  fruits  and  vegetables.  All  the 
starchy  substances  of  the  food  are  also  converted  into  sugar  in  the 
process  of  digestion.  Two  of  the  varieties  of  sugar,  at  least, 
originate  in  the  interior  of  the  body,  viz.,  sugar  of  milk  and  liver 
sugar.  The  former  exists  in  a  solid  form  in  the  substance  of  the 
mammary  gland,  from  which  it  passes  in  solution  into  the  milk. 
The  liver  sugar  is  found  in  the  substance  of  the  liver,  and  almost 
always  also  in  the  blood  of  the  hepatic  veins.  The  sugar  which  is 
introduced  with  the  food,  as  well  as  that  which  is  formed  in  the 
liver,  disappears  by  decomposition  in  the  animal  fluids,  and  does 
not  appear  in  any  of  the  excretions. 


8.  Fats. — These  substances,  like  the  sugars,  are  derived  from 
both  animal  and  vegetable  sources.  There  are  three  principal 
varieties  of  them,  which  may  be  considered  as  representing  the 
class,  viz  : — 

Oleine '        .         .     =  Cg^  H^^  0,5 

Margarine       ......=  C^g  H^j  0,2 

Stearine  ......=  Ci^gH^iO^y 

The  principal  difference  between  the  oleaginous  and  saccharine 
substances,  so  far  as  regards  their  ultimate  chemical  composition, 
is  that  in  the  sugars  the  oxygen  and  hydrogen  always  exist  together 
in  the  proportion  to  form  water;  while  in  the  fats  the  proportions  of 
carbon  and  hydrogen  are  nearly  the  same,  but  that  of  oxygen  is 
considerably  less.  The  fats  are  all  fluid  at  a  high  temperature,  but 
assume  the  solid  form  on  cooling.  Stearine,  which  is  the  most 
solid  of  the  three,  liquefies  only  at  148°  F.;  margarine  at  118°  F.; 
while  oleine  remains  fluid  considerably  below  100°  F.,  and  even 
very  near  the  freezing  point  of  water.  The  fats  are  all  insoluble 
in  water,  but  readily  soluble  in  ether.  When  treated  with  a  solu- 
tion of  a  caustic  alkali,  they  are  decomposed,  and  as  the  result  of 


FATS. 


55 


the  decomposition  tliere  are  formed  two  new  bodies ;  first,  glycerine, 
which  is  a  neutral  fluid  substance,  and  secondly,  a  fatty  acid,  viz : 
oleic,  margaric,  or  stearic  acid,  corresponding  to  the  kind  of  fat 
which  has  been  used  in  the  experiment.  The  glycerine  remains  in 
a  free  state,  while  the  fatty  acid  unites  with  the  alkali  employed, 
forming  an  oleate,  margarate,  or  stearate.  This  combination  is 
termed  a  soap^  and  the  process  by  which  it  is  formed  is  called 
saponification.  This  process,  however,  is  not  a  simple  decomposition 
of  the  fatty  body,  since  it  can  only  take  place  in  the  presence  of 
water;  several  equivalents  of  which  unite  with  the  elements  of  the 
fatty  body,  and  enter  into  the  composition  of  the  glycerine,  &c.,  so 
that  the  fatty  acid  and  the  glycerine  together  weigh  more  than  the 
original  fatty  substance  which  was  decomposed.  It  is  not  proper, 
therefore,  to  regard  an  oleaginous  body  as  formed  by  the  union  of  a 
fatty  acid  with  glycerine.  It  is  formed,  on  the  contrary,  in  all  pro- 
bability, by  the  direct  combination  of  its  ultimate  chemical  elements. 
The  different  kinds  of  oil,  fat,  lard,  suet,  &c.,  contain  the  three 
oleaginous  matters  mentioned  above,  mingled  together  in  different 
proportions.  The  more  solid  fats  contain  a  larger  quantity  of 
stearine  and  margarine;  the  less  consistent  varieties,  a  larger  propor- 
tion of  oleine.  Neither  of  the  oleaginous  matters,  stearine,  mar- 
garine, or  oleine,  ever  occur  separately  ;  but  in  every  fatty  substance 
they  are  mingled  together,  so  that  the  more  fluid  of  them  hold  in 
solution  the  more  solid. 
Generally  speaking,  in  the 
living  body,  these  mixtures 
are  fluid  or  nearly  so ;  for 
though  both  stearine  and 
margarine  are  solid,  when 
pure,  at  the  ordinary  tem- 
perature of  the  body,  they 
are  held  in  solution,  during 
life,  by  the  oleine  with  which 
they  are  associated.  After 
death,  however,  as  the  body 
cools,  tlie  stearine  and  mar- 
garine sometimes  separate 
from  the  mixture  in  a  crys- 
talline form,  since  the  oleine 
can  no  longer  hold  in  solution  so  large  a  quantity  of  them  as  it  had 
dissolved  at  a  higher  temperature. 


Steakine  crystallized  from  a  Warm  Solution  in  Oleine. 


56         PEOXIMATE    PEINCIPLES    OF    THE    SECOND    CLASS. 

These  substances  crystallize  in  very  slender  needles,  which  are 
sometimes  straight,  but  more  often  somewhat  curved  or  wavy  in 
their  outline.  (Fig.  7.) 

They  are  always  deposited  in  a  more  or  less  radiated  form  ;  and 
have  sometimes  a  very  elegant,  branched,  or  arborescent  arrange- 
ment. 

When  in  a  fluid  state,  the  fatty  substances  present  themselves 

under  the  form  of  drops  or 
globules,  which  vary  indefi- 
nitely in  size,  but  which 
may  be  readily  recognized 
by  their  optical  properties. 
They  are  circular  in  shape, 
and  have  a  faint  amber  color, 
distinct  in  the  larger  globules, 
less  so  in  the  smaller.  They 
have  a  sharp,  well  defined 
outline  (Fig.  8);  and  as  they 
refract  the  light  strongly, 
and  act  therefore  as  double 
convex  lenses,  they  present 
a  brilliant  centre,  surrounded 
by  a  dark  border.  These 
marks  will  generally  be 
sufficient  to  distinguish  them  under  the  microscope. 

The  following  list  shows  the  percentage  of  oily  matter  present  in 
various  kinds  of  animal  and  vegetable  food.* 


Oleaginous  Principles  of  Human  Fat.    Stearine  and 
Margarine  crystallized;   Oleine  Fluid. 


Quantity  of  Fat  in  100  parts  in 


Filberts . 
Walnuts 
Cocoa-nuts 
Olives  . 
Linseed . 
Indian  corn 
Yolk  of  eggs 


60.00 
50.00 
47.00 
32.00 
22.00 
9.00 
28.00 


Ordinary  meat 
Liver  of  the  ox 
Cow's  milk  . 
Human  milk  . 
Asses'  milk  . 
Goat's  milk    . 


14.30 
3.89 
3.13 
3.55 
0.11 
3.32 


The  oleaginous  matters  present  a  striking  peculiarity  as  to  the 
form  under  which  they  exist  in  the  animal  body ;  a  peculiarity 
which  distinguishes  them  from  all  the  other  proximate  principles. 
The  rest  of  the  proximate  principles  are  all  intimately  associated 
together  by  molecular  union,  so  as  to  form  either  clear  solutions  or 


Pereira,  op.  cit.,  p.  81. 


FATS.  67 

homogeneous  solids.  Thus,  the  sugars  of  the  blood  are  in  solution 
in  water,  in  company  with  the  albumen,  the  phosphate  of  lime, 
chloride  of  sodium,  and  the  like ;  all  of  them  equally  distributed 
throughout  the  entire  mass  of  the  fluid.  In  the  bones  and  car- 
tilages, the  animal  matters  and  the  calcareous  salts  are  in  similarly 
intimate  union  with  each  other ;  and  in  every  other  part  of  the 
body  the  animal  and  inorganic  ingredients  are  united  in  the  same 
Avay.  But  it  is  different  with  the  fats.  For,  while  the  three  prin- 
cipal varieties  of  oleaginous  matter  are  always  united  with  each 
other,  they  are  not  united  with  any  of  the  other  kinds  of  proximate 
principles;  that  is,  with  water,  saline  substances,  sugars,  or  albu- 
minous matters.  Almost  the  only  exception  to  this  is  in  the  nerv- 
ous tissue;  in  which,  according  to  Robin  and  Verdeil,  the  oily 
matters  seem  to  be  united  with  an  albuminoid  substance.  Another 
exception  is,  perhaps,  in  the  bile ;  since  some  of  the  biliary  salts 
have  the  power  of  dissolving  a  certain  quantity  of  fat.  Every- 
where else,  instead  of  forming  a  homogeneous  solid  or  fluid  with 
the  other  proximate  principles,  the  oleaginous  matters  are  found 
in  distinct  masses  or  globules,  which  are  suspended  in  serous  fluids, 
interposed  in  the  interstices  between  the  anatomical  elements,  in- 
cluded in  the  interior  of  cells,  or  deposited  in  the  substance  of 
fibres  or  membranes.  Even  in  the  vegetable  tissues,  the  oil  is 
always  deposited  in  this  manner  in  distinct  drops  or  granules. 

Owing  to  this  fact,  the  oils  can  be  easily  extracted  from  the 
organized  tissues  by  the  employment  of  simply  mechanical  pro- 
cesses. The  tissues,  animal  or  vegetable,  are  merely  cut  into  small 
pieces  and  subjected  to  pressure,  by  which  the  oil  is  forced  out 
from  the  parts  in  which  it  was  entangled,  and  separated,  without  any 
further  manipulation,  in  a  state  of  purity.  A  moderately  elevated 
temperature  facilitates  the  operation  by  increasing  the  fluidity  of 
the  oleaginous  matter ;  but  no  other  chemical  agency  is  required 
for  its  separation.  Under  the  microscope,  also,  the  oil  drops  and 
granules  can  be  readily  perceived  and  distinguished  from  the 
remaining  parts  of  the  tissue,  and  can,  moreover,  be  easily  re- 
cognized by  the  dissolving  action  of  ether,  which  acts  upon 
them,  as  a  general  rule,  without  attacking  the  other  proximate 
principles. 

Oils  are  found,  in  the  animal  body,  most  abundantly  in  the 
adipose  tissue.  Here  they  are  contained  in  the  interior  of  the 
adipose  vesicles,  the  cavities  of  which  they  entirely  fill,  in  a  state 


58 


PEOXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 


Human  Adipose  Tissue. 


of  health.     These  vesicles  are  transparent,  and  have  a  somewhat 
angular  form,  owing  to  their  mutual  compression.  (Fig.  9.)     They 

vary  in  diameter,  in  the  hu- 
man subject,  from  ^^^  to  ^^j^ 
of  an  inch,  and  are  composed 
of  a  thin,  structureless  ani- 
mal membrane,  forming  a 
closed  sac,  in  the  interior  of 
which  the  oily  matter  is  con- 
tained. There  is  here,  ac- 
cordingly, no  union  whatever 
of  the  oil  with  the  other 
proximate  principles,  but 
only  a  mechanical  inclusion 
of  them  by  the  walls  of  the 
vesicles.  Sometimes,  when 
emaciation  is  going  on,  the 
oil  partially  disappears  from 
the  cavity  of  the  adipose  vesicle,  and  its  place  is  taken  by  a  watery 
serum ;  but  the  serous  and  oily  fluids  always  remain  distinct,  and 
occupy  different  parts  of  the  cavity  of  the  vesicle. 

In  the  chyle,  the  oleaginous  matter  is  in  a  state  of  emulsion  or 
suspension  in  the  form  of  minute  particles  in  a  serous  fluid.     Its 

subdivision  is  here  more  com- 
Fig.  10.  plete,  and  its  molecules  more 

minute  than  anywhere  else  in 
the  body.  It  presents  the  ap- 
pearance of  a  fine  granular 
dust,  which  has  been  known 
by  the  name  of  the  "  molecu- 
lar base  of  the  chyle."  A 
few  of  these  granules  are  to 
be  seen  which  measure  xo^oo 
of  an  inch  in  diameter ;  but 
they  are  generally  much  less 
than  this,  and  the  greater  part 
are  so  small  that  they  cannot 
be  accurately  measured.  (Fig. 
10.)  For  the  same  reason 
they  do  not  present  the  bril- 
liant centre  and  dark  border  of  the  larger  oil-globules ;  but  appear 


Chyle,  from  commencemeut  of  Thoracic  Duct,  from 
the  Dog. 


FATS. 


59 


o°  o%^.  0 


by  transmitted  light  only  as  minute  dark  granules.  The  white 
color  and  opacity  of  the  chyle,  as  of  all  other  fatty  emulsions, 
depend  upon  this  molecular  condition  of  the  oily  ingredients.  The 
albumen,  salts,  &c.,  which  are  in  intimate  union  with  each  other, 
and  in  solution  in  the  water,  would  alone  make  a  colorless  and 
transparent  fluid;  but  the  oily  matters,  suspended  in  distinct  par 
tides,  which  have  a  different  refractive  power  from  the  serous  fluid, 
interfere  with  its  transparency 
and  give  it  the  white  color  and 
opaque  appearance  which  are 
characteristic  of  emulsions. 
The  oleasfinous  nature  of  these 
particles  is  readily  shown  by 
their  solubility  in  ether. 

In  the  milk,  the  oily  matter 
occurs  in  larger  masses  than 
in  the  chyle.  In  cow's  milk 
(Fig.  11),  these  oil-drops,  or 
"  milk-globules,"  are  not  quite 
fluid,  but  have  a  pasty  con- 
sistency, owing  to  the  large 
quantity  of  margarine  which 
they  contain,  in  proportion  to 

the  oleine.  When  forcibly  amalgamated  with  each  other  and 
collected  into  a  mass  by  prolonged  beating  or  churning,  they  con- 
stitute butter.  In  cow's  milk, 
the  globules  vary  somewhat 
in  size,  but  their  average 
diameter  is  40V0  of  ^^  inch. 
They  are  simply  suspended 
in  the  serous  fluid  of  the 
milk,  and  are  not  covered 
with  any  albuminous  mem- 
brane. 

In  the  cells  of  the  laryn- 
geal, tracheal,  and  costal  car- 
tilages (Fig.  12),  there  is 
always  more  or  less  fat  de- 
posited in  the  form  of  round- 
ed globules,  somewhat  simi- 

,  ,  PI  •11  Cells  OF  Costal  Cartilages,  containing  Oil-Globules. 

lar  to  those  01  the  milk.  Human. 


Globules  of  Cow's  Milk. 


Fia;.  12. 


60         PROXIMATE    PRINCIPLES    OF    THE    SECOND    CLASS. 


Hepatic  Cells.    Human. 


In  the  glandular  cells  of  the  liver,  oil  occurs  constantly,  in  a 
state  of  health.     It  is  here  deposited  in  the  substance  of  the  cell 

(Fig.  13),  generally  in  smaller 
globules  than  the  preceding. 
In  some  cases  of  disease,  it 
accumulates  in  excessive 
quantity,  and  produces  the 
state  known  as  fatty  degene- 
ration of  the  liver.  This  is 
consequently  only  an  ex- 
aggerated condition  of  that 
which  normally  exists  in 
health. 

In  the  carnivorous  ani- 
mals, oil  exists  in  considera- 
ble quantity  in  the  convo- 
luted portion  of  the  urini- 
ferous  tubules.  (E'ig.  14.)  It 
is  here  in  the  form  of  granules  and  rounded  drops,  which  some- 
times appear  to  fill  nearly  the  whole  calibre  of  the  tubules. 

It  is  found  also  in  the  secreting  cells  of  the  sebaceous  and  other 

glandules,  deposited  in  the 
same  manner  as  in  those  of 
the  liver,  but  in  smaller 
quantity.  It  exists,  beside, 
in  large  proportion,  in  a 
granular  form,  in  the  secre- 
tion of  the  sebaceous  gland- 
ules. 

It  occurs  abundantly  in 
the  marrow  of  the  bones, 
both  under  the  form  of  free 
oil-globules  and  inclosed  in 
the  vesicles  of  adipose  tissue. 
It  is  found  in  considerable 
quantity  in  the  substance  of 
the  yellow  wall  of  the  corpus 
luteum,  and  is  the  immediate 
cause  of  the  peculiar  color  of  this  body. 

It  occurs  also  in  the  form  of  granules  and  oil-drops  in  the 
muscular  fibres  of  the  uterus  (Fig.  15),  in  which  it  begins  to  be 


Uriniferods  Tubules  of  Dog,  from  Cortical  Portion  of 
Kidney. 


FATS. 


61 


MrscnLAR  Fibres  of  Human  TJterits  three  weeks  after 
parturition. 


deposited  sood  after  delivery,  and  where  it  continues  to  be  present 
during  the  whole  period  of  the  resorption  or  involution  of  this  organ. 

lu  all  these  instances,  the  oleaginous  matters  remain  distinct  in 
form  and  situation  from  the 

other  ingredients  of  the  ani-  ^ig-  15. 

mal  frame,  and  are  only  me- 
chanically entangled  among 
its  fibres  and  cells,  or  im- 
bedded separately  in  their 
interior. 

A  large  part  of  the  fat 
which  is  found  in  the  body 
may  be  accounted  for  by  that 
which  is  taken  in  with  the 
food,  since  oily  matter  occurs 
in  both  animal  and  vegetable 
substances.  Fat  is,  however, 
formed  in  the  body,  independ- 
ently of  what  is  introduced 
with  the  food.  This  im- 
portant fact  has  been  definitely  ascertained  by  the  experiments  of 
MM.  Dumas  and  Milne-Edwards  on  bees,*  M.  Persoz  on  geese,^  and 
finally  by  those  of  M.  Boussingault  on  geese,  ducks,  and  pigs.^  The 
observers  first  ascertained  the  quantity  of  fat  existing  in  the  whole 
body  at  the  commencement  of  the  experiment.  The  animals  were 
then  subjected  to  a  definite  nutritious  regimen,  in  which  the 
quantity  of  fatty  matter  was  duly  ascertained  by  analysis.  The 
experiments  lasted  for  a  period  varying,  in  different  instances,  from 
thirty-one  days  to  eight  months;  after  which  the  animals  were 
killed  and  all  their  tissues  examined.  The  result  of  tbese  investi- 
gations showed  that  considerably  more  fat  had  been  accumulated 
by  the  animal  during  the  course  of  the  experiment  than  could  be 
accounted  for  by  that  which  existed  in  the  food;  and  placed  it 
beyond  a  doubt  that  oleaginous  substances  may  be,  and  actually 
are,  formed  in  the  interior  of  tbe  animal  body  by  the  decomposition 
or  metamorphosis  of  other  proximate  principles. 

It  is  not  known  from  what  proximate  principles  the  fat  is  pro- 
duced, when  it  originates  in  this  way  in  the  interior  of  the  body. 
Particular  kinds  of  food  certainly  favor  its  production  and  accu- 


'  Annales  de  China,  et  de  Phys.,  3d  series,  vol.  xiv.  p.  400. 
^  Chimie  Agdcole,  Paris,  1854. 


2  Ibid.,  p.  408. 


62       proxi:mate  peixciples  of  the  secoxd  class, 

mulation  to  a  considerable  degree.  It  is  well  known,  for  instance, 
that  in  sugar-growing  countries,  as  in  Louisiana  and  the  West 
Indies,  during  the  few  weeks  occupied  in  gathering  the  cane  and 
extracting  the  sugar,  all  the  negroes  employed  on  the  plantations, 
and  even  the  horses  and  cattle,  that  are  allowed  to  feed  freely  on 
the  saccharine  juices,  grow  remarkably  fat;  and  that  they  again  lose 
their  superabundant  flesh  when  the  season  is  past.  Even  in  these 
instances,  however,  it  is  not  certain  whether  the  saccharine  substances 
are  directly  converted  into  fat,  or  whether  they  are  first  assimilated 
and  only  afterward  supply  the  materials  for  its  production.  The 
abundant  accumulation  of  fat  in  certain  regions  of  the  body,  and  its 
absence  in  others;  and  more  particularly  its  constant  occurrence  in 
certain  situations  to  which  it  could  not  be  transported  by  the  blood, 
as  for  example  the  interior  of  the  cells  of  the  costal  cartilages,  the 
substance  of  the  muscular  fibres  of  the  uterus  after  parturition,  &c,, 
make  it  probable  that  under  ordinary  conditions  the  oily  matter  is 
formed  by  decomposition  of  the  tissues  upon  the  very  spot  where  it 
subsequently  makes  its  appearance. 

In  the  female  during  lactation  a  large  part  of  the  oily  matter  in- 
troduced with  the  food,  or  formed  in  the  body,  is  discharged  with 
the  milk,  and  goes  to  the  support  of  the  infant.  But  in  the  female 
in  the  intervals  of  lactation,  and  in  the  male  at  all  times,  the  oily 
matters  almost  entirely  disappear  by  decomposition  in  the  interior 
of  the  body ;  since  the  small  quantity  which  is  discharged  with  the 
sebaceous  matter  by  the  skin  bears  only  an  insignificant  proportion 
to  that  which  is  introduced  daily  with  the  food. 

The  most  important  characteristic,  in  a  physiological  point  of 
view,  of  the  proximate  principles  of  the  second  class,  relates  to  their 
origin  and  their  final  destination.  Not  only  are  they  all  of  a  purely 
organic  origin,  making  their  appearance  first  in  the  interior  of  vege- 
tables ;  but  the  sugars  and  the  oils  are  formed  also,  to  a  certain  ex- 
tent, in  the  bodies  of  animals;  continuing  to  make  their  appearance 
when  no  similar  substances,  or  only  an  insufficient  quantity  of  them, 
have  been  taken  with  the  food.  Furthermore,  when  introduced 
with  the  food,  or  formed  in  the  body  and  deposited  in  the  tissues, 
these  substances  do  not  reappear  in  the  secretions.  They,  therefore, 
for  the  most  part  disappear  by  decomposition  in  the  interior  of  the 
body.  They  pass  through  a  series  of  changes  by  which  their  es- 
sential characters  are  destroyed ;  and  they  are  finally  replaced  in 
the  circulation  by  other  substances,  which  are  discharged  with  the 
excreted  fluids. 


PROXIMATE    PRINCIPLES    OF    THE    THIRD    CLASS.  63 


CHAPTER   IV. 

PROXIMATE    PRINCIPLES   OF   THE    THIRD    CLASS. 

The  substances  belonging  to  this  class  are  very  important,  and 
form  by  far  the  greater  part  of  the  entire  mass  of  the  body.  They 
are  derived  both  from  animal  and  vegetable  sources.  They  have 
been  known  by  the  name  of  the  "protein  compounds"  and  the 
"  albuminoid  substances."  The  name  organic  substances  was  given 
to  them  by  Robin  and  Verdeil,  by  whom  their  distinguishing  pro- 
perties were  first  accurately  described.  They  have  not  only  an 
organic  origin,  in  common  with  the  proximate  principles  of  the 
second  class,  but  their  chemical  constitution,  their  physical  struc- 
ture and  characters,  and  the  changes  which  they  undergo,  are  all  so 
different  from  those  met  with  in  any  other  class,  that  the  term  "or- 
ganic substances"  proper,  appears  particularly  appropriate  to  them. 

Their  first  peculiarity  is  that  they  are  not  crystallizable.  They 
always,  when  pure,  assume  an  amorphous  condition,  which  is  some- 
times solid  (organic  substance  of  the  bones),  sometimes  fluid  (albu- 
men of  the  blood),  and  sometimes  semi-solid  in  consistency,  midway 
between  the  solid  and  fluid  condition  (organic  substance  of  the  mus- 
cular fibre). 

Their  chemical  constitution  differs  from  that  of  bodies  of  the 
second  class,  first  in  the  fact  that  they  all  contain  the  four  chemical 
elements,  oxygen,  hydrogen,  carbon,  and  nitrogen ;  while  the  starches, 
sugars,  and  oils  are  destitute  of  the  last  named  ingredient.  The  or- 
ganic matters  have  therefore  been  sometimes  known  by  the  name 
of  the  "  nitrogenous  substances,"  while  the  sugars,  starch,  and  oils 
have  been  called  "non-nitrogenous."  Some  of  the  organic  matters, 
viz.,  albumen,  fibrin,  and  casein,  contain  sulphur  also,  as  an  ingre- 
dient; and  others,  viz.,  the  coloring  matters,  contain  iron.  The 
remainder  consist  of  oxygen,  hydrogen,  carbon,  and  nitrogen  alone. 

The  most  important  peculiarity,  however,  of  the  organic  sub- 
stances, relating  to  their  chemical  composition,  is  that  it  is  not  defi- 
nite.    That  is  to  say,  they  do  not  always  contain  precisely  the  same 


64  PEOXIMATE    PEIISrCIPLES    OF    THE    THIED    CLASS. 

proportions  of  oxygen,  hydrogen,  carbon,  and  nitrogen ;  but  the  re- 
lative quantities  of  these  elements  vary  within  certain  limits,  in 
different  individuals  and  at  different  times,  without  modifying,  in 
any  essential  degree,  the  peculiar  properties  of  the  animal  matters 
which  they  constitute.  This  fact  is  altogether  a  special  one,  and 
characteristic  of  organic  substances.  No  substance  having  a  definite 
chemical  composition,  like  phosphate  of  lime,  starch,  or  olein,  can 
suffer  the  slightest  change  in  its  ultimate  constitution  without  being, 
by  that  fact  alone,  totally  altered  in  its  essential  properties.  If 
phosphate  of  lime,  for  example,  were  to  lose  one  or  two  equivalents 
of  oxygen,  an  entire  destruction  of  the  salt  would  necessarily  result, 
and  it  would  cease  to  be  phosphate  of  lime.  For  its  properties  as  a 
salt  depend  entirely  upon  its  ultimate  chemical  constitution;  and  if 
the  latter  be  changed  in  any  way,  the  former  are  necessarily  lost. 

But  the  properties  which  distinguish  the  organic  substances,  and 
which  make  them  important  as  ingredients  of  the  body,  do  not 
depend  immediately  upon  their  ultimate  chemical  constitution,  and 
are  of  a  peculiar  character ;  being  such  as  are  only  manifested  in  the 
interior  of  the  living  organism.  Albumen,  therefore,  though  it  may 
contain  a  few  equivalents  more  or  less  of  oxygen  or  nitrogen,  does 
not  on  that  account  cease  to  be  albumen,  so  long  as  it  retains  its 
fluidity  and  its  aptitude  for  undergoing  the  processes  of  absorption 
and  transformation,  which  characterize  it  as  an  ingredient  of  the 
living  body. 

It  is  for  this  reason  that  considerable  discrepancy  has  existed  at 
various  times  among  chemists  as  to  the  real  ultimate  composition 
of  these  substances,  different  experimenters  often  obtaining  different 
analytical  results.  This  is  not  owing  to  any  inaccuracy  in  the 
analyses,  but  to  the  fact  that  the  organic  substance  itself  really  has 
a  different  ultimate  constitution  at  different  times.  The  most  ap- 
proved formulae  are  those  which  have  been  established  by  Liebig 
for  the  following  substances: — 

Fibrin =  C29gH228N4o092S2 

Albumen =  C2,6H,g9N270g8S2 

Casein  ......=  C288H22sN3gOggS2 

Owing  to  the  above  mentioned  variations,  however,  the  same 
degree  of  importance  does  not  attach  to  the  quantitative  ultimate 
analysis  of  an  organic  matter,  as  to  that  of  other  substances. 

This  absence  of  a  definite  chemical  constitution  in  the  organic  sub- 
stances is  undoubtedly  connected  with  their  incapacity  for  crystalli- 
zation.    It  is  also  connected  with  another  almost  equally  peculiar 


OEGANIC    SUBSTANCES.  65 

fact,  viz.,  that  although  the  organic  substances  unite  with  acids  and 
with  alkalies,  they  do  not  play  the  part  of  an  acid  toward  the  base, 
or  of  a  base  toward  the  acid ;  for  the  acid  or  alkaline  reaction  of 
the  substance  employed  is  nqt  neutralized,  but  remains  as  strong- 
after  the  combination  as  before.  Furthermore,  the  union  does  not 
take  place,  so  far  as  can  be  ascertained,  in  any  definite  proportions. 
The  organic  substances  have,  in  fact,  no  combining  equivalent;  and 
their  molecular  reactions  and  the  changes  which  they  undergo  in 
the  body  cannot  therefore  be  expressed  by  the  ordinary  chemical 
phrases  which  are  adapted  to  inorganic  substances.  Their  true 
characters,  as  proximate  principles,  are  accordingly  to  be  sought  for 
in  other  properties  than  those  which  depend  upon  their  exact  ulti- 
mate composition. 

One  of  these  characters  is  that  they  are  hygroscopic.  As  met  with 
in  different  parts  of  the  body,  they  present  different  degrees  of  con- 
sistency; some  being  nearly  solid,  others  more  or  less  fluid.  But  on 
being  subjected  to  evaporation  they  all  lose  water,  and  are  reduced 
to  a  perfectly  solid  form.  If  after  this  desiccation  they  are  exposed 
to  the  contact  of  moisture,  they  again  absorb  water,  swell,  and 
regain  their  original  mass  and  consistency.  This  phenomenon  is 
quite  different  from  that  of  capillary  attraction,  by  which  some  in- 
organic substances  become  moistened  when  exposed  to  the  contact 
of  water;  for  in  the  latter  case  the  water  is  simply  entangled  me- 
chanically in  the  meshes  and  pores  of  the  inorganic  body,  while  that 
which  is  absorbed  by  the  organic  matter  is  actually  united  with  its 
substance,  and  diffused  equally  throughout  its  entire  mass.  Every 
organic  matter  is  naturally  united  in  this  way  with  a  certain  quantity 
of  water,  some  more  and  some  less.  Thus  the  albumen  of  the  blood 
is  in  union  with  so  much  water  that  it  has  the  fluid  form,  while  the 
organic  substance  of  cartilage  contains  less  and  is  of  a  firmer  con- 
sistency. The  quantity  of  water  contained  in  each  organic  sub- 
stance may  be  diminished  by  artificial  desiccation,  or  by  a  deficient 
supply ;  but  neither  of  them  can  be  made  to  take  up  more  than  a 
certain  amount.  Thus  if  the  albumen  of  the  blood  and  the  organic 
substance  of  cartilage  be  both  reduced  by  evaporation  to  a  similar 
degree  of  dryness  and  then  placed  in  water,  the  albumen  will  absorb 
so  much  as  again  to  become  fluid,  but  the  cartilaginous  substance 
only  so  much  as  to  regain  its  usual  nearly  solid  consistency.  Even 
where  the  organic  substance,  therefore,  as  in  the  case  of  albumen, 
becomes  fluid  under  these  circumstances,  it  is  not  exactly  a  solution 
5 


66  PEOXIMATE    PRINCIPLES    OF    THE    THIRD    CLASS. 

of  it  in  water,  but  only  a  reabsorption  by  it  of  that  quantity  of  fluid 
with  which  it  is  naturally  associated. 

Another  peculiar  phenomenon  characteristic  of  organic  substances 
is  their  coagulation.  Those  which  are  naturally  fluid  suddenly  as- 
sume, under  certain  conditions,  a  solid  or  semi-solid  consistency. 
They  are  then  said  to  be  coagulated;  and  after  coagulation  they 
cannot  be  made  to  reassume  their  original  condition.  Thus  fibrin 
coagulates  on  being  withdrawn  from  the  bloodvessels,  albumen  on 
being  subjected  to  the  temperature  of  boiling  water,  casein  on  being 
placed  in  contact  with  an  acid.  When  an  organic  substance  thus 
coagulates,  the  change  which  takes  place  is  a  peculiar  one,  and  has 
no  resemblance  to  the  precipitation  of  a  solid  substance  from  a 
watery  solution.  On  the  contrary,  the  organic  substance  merely 
assumes  a  special  condition;  and  in  passing  into  the  solid  form  it 
retains  all  the  water  with  which  it  was  previously  united.  Albumen, 
for  example,  after  coagulation,  retains  the  same  quantity  of  water  in 
union  with  it,  which  it  held  before.  After  coagulation,  accordingly, 
this  water  may  be  driven  off  by  evaporation,  in  the  same  manner  as 
previously;  and  on  being  again  exposed  to  moisture,  the  organic 
matter  will  again  absorb  the  same  quantity,  though  it  will  not  re- 
sume the  fluid  form. 

By  coagulation,  an  organic  substance  is  permanently  altered ; 
and  though  it  may  be  afterwards  dissolved  by  certain  chemical  re- 
agents, as,  for  example,  the  caustic  alkalies,  it  is  not  thereby  restored 
to  its  original  condition,  but  only  suffers  a  still  further  alteration. 

In  many  instances  we  are  obliged  to  resort  to  coagulation  in  order 
to  separate  an  organic  substance  from  the  other  proximate  principles 
with  which  it  is  associated.  This  is  the  case,  for  example,  with  the 
fibrin  of  the  blood,  which  is  obtained  in  the  form  of  flocculi,  by 
beating  freshly  drawn  blood  with  a  bundle  of  rods.  But  when 
separated  in  this  way,  it  is  already  in  an  unnatural  condition,  and 
no  longer  represents  exactly  the  original  fluid  fibrin,  as  it  existed 
in  the  circulating  blood.  Nevertheless,  this  is  the  only  mode  in 
which  it  can  be  examined,  as  there  are  no  means  of  bringing  it  back 
to  its  previous  condition. 

Another  important  property  of  the  organic  substances  is  that 
they  readily  excite,  in  other  proximate  principles  and  in  each  other, 
those  peculiar  indirect  chemical  changes  which  are  termed  catalyses 
or  catalytic  transformations.  That  is  to  say,  they  produce  the  changes 
referred  to,  not  directly,  by  combining  with  the  substance  which 
suffers  alteration,  or  with  any  of  its  ingredients;  but  simply  by  their 


#* 


ORGANIC    SUBSTANCES.  67 

presence,  which  induces  the  chemical  change  in  an  indirect  manner. 
Thus,  the  organic  substances  of  the  intestinal  fluids  induce  a  cata- 
lytic action  by  which  starch  is  converted  into  sugar.  The  albumen 
of  the  blood,  by  contact  with  the  organic  substance  of  the  muscular 
fibre,  is  transformed  into  a  substance  similar  to  it.  The  entire 
process  of  nutrition,  so  far  as  the  organic  matters  are  concerned, 
consists  of  such  catalytic  transformations.  Many  crystallizable 
substances,  which  when  pure  remain  unaltered  in  the  air,  become 
changed  if  mingled  with  organic  substances,  even  in  small  quantity. 
Thus  the  casein  of  milk,  after  being  exposed  for  a  short  time  to  a 
warm  atmosphere,  becomes  a  catalytic  body,  and  converts  the  sugar 
of  the  milk  into  lactic  acid.  In  this  change  there  is  no  loss  nor 
addition  of  any  chemical  element,  since  lactic  acid  has  precisely  the 
same  ultimate  composition  with  sugar  of  milk.  It  is  simply  a 
transformation  induced  by  the  presence  of  the  casein.  Oily  matters, 
which  are  entirely  unalterable  when  pure,  readily  become  rancid  at 
warm  temperatures,  if  mingled  with  an  organic  impurity. 

Fourthly,  The  organic  substances,  when  beginning  to  undergo 
decay,  induce  in  certain  other  substances  the  phenomenon  of  fer- 
mentation. Thus,  the  mucus  of  the  urinary  bladder,  after  a  short 
exposure  to  the  atmosphere,  causes  the  urea  of  the  urine  to  be  con- 
verted into  carbonate  of  ammonia,  with  the  development  of  gaseous 
bubbles.  The  organic  matters  of  grape  juice,  under  similar  circum- 
stances, give  rise  to  fermentation  of  the  sugar,  by  which  it  is  con- 
verted into  alcohol  and  carbonic  acid. 

Fifthly,  The  organic  substances  are  the  only  ones  capable  of 
undergoing  the  process  of  'putrefaction.  This  process  is  a  compli- 
cated one,  and  is  characterized  by  a  gradual  liquefaction  of  the  ani- 
mal substance,  by  many  mutual  decompositions  of  the  saline  matters 
which  are  associated  with  it,  and  by  the  development  of  peculiarly 
fetid  and  unwholesome  gases,  among  which  are  carbonic  acid, 
nitrogen,  sulphuretted,  phosphoretted,  and  carburetted  hydrogen, 
and  ammoniacal  vapors.  Putrefaction  takes  place  constantly  after 
death,  if  the  organic  tissue  be  exposed  to  a  moist  atmosphere  at  a 
moderately  warm  temperature.  It  is  much  hastened  by  the  presence 
of  other  organic  substances,  in  which  decomposition  has  already 
commenced. 

The  organic  substances  are  readily  distinguished,  by  the  above 
general  characters,  from  all  other  kinds  of  proximate  principles. 
They  are  quite  numerous;  nearly  every  animal  fluid  and  tissue  con- 
taining at  least  one  which  is  peculiar  to  itself.  They  have  not  as 
yet  been  all  accurately  described.     The  following  list,  however, 


68  PEOXIMATE    PRINCIPLES    OF    THE    THIRD    CLASS. 

comprises  the  most  important  of  them,  and  those  with  which  we 
are  at  present  most  thoroughly  acquainted.  The  first  seven  are  fluid, 
or  nearly  so,  and  either  colorless  or  of  a  faint  yellowish  tinge. 

1.  Fibrin. — Fibrin  is  found  in  the  blood ;  where  it  exists,  in  the 
human  subject,  in  the  proportion  of  two  to  three  parts  per  thousand. 
It  is  fluid,  and  mingled  intimately  with  the  other  ingredients  of  the 
blood.  It  occurs  also,  but  in  much  smaller  quantity,  in  the  lymph. 
It  is  distinguished  by  what  is  called  its  "spontaneous"  coagulation; 
that  is,  it  coagulates  on  being  withdrawn  from  the  vessels,  or  on  the 
occurrence  of  any  stoppage  to  the  circulation.  It  is  rather  more 
abundant  in  the  blood  of  some  of  the  lower  animals  than  in  that  of 
the  human  subject.  In  general,  it  is  found  in  larger  quantity  in 
the  blood  of  the  herbivora  than  in  that  of  the  carnivora. 

2.  Albumen. — Albumen  occurs  in  the  blood,  the  lymph,  the- 
fluid  of  the  pericardium,  and  in  that  of  the  serous  cavities  gene- 
rally. It  is  also  present  in  the  fluid  which  may  be  extracted  by 
pressure  from  the  muscular  tissue.  In  the  blood  it  occurs  in  the 
proportion  of  about  seventy-five  parts  per  thousand.  The  white  of 
egg,  which  usually  goes  by  the  same  name,  is  not  identical  with  the 
albumen  of  the  blood,  though  it  resembles  it  in  some  respects;  it  is 
properly  a  secretion  from  the  mucous  membrane  of  the  fowl's  ovi- 
duct, and  should  be  considered  as  a  distinct  organic  substance. 
Albumen  coagulates  on  being  raised  to  the  temperature  of  160°  F.; 
and  the  coagulum,  like  that  of  all  the  other  proximate  principles,  is 
soluble  hi  caustic  potass.  It  coagulates  also  by  contact  with  alco- 
hol, the  mineral  acids,  ferrocyanide  of  potassium  in  an  acidulated 
solution,  tannin,  and  the  metallic  salts.  The  alcoholic  coagulum,  if 
separated  from  the  alcohol  by  washing,  does  not  redissolve  in  water. 
A  very  small  quantity  of  albumen  has  been  sometimes  found  in  the 
saliva. 

3.  Casein. — This  substance  exists  in  milk,  in  the  proportion  of 
about  forty  parts  per  thousand.  It  coagulates  by  contact  with  all 
the  acids,  mineral  and  organic ;  but  is  not  affected  by  a  boiling 
temperature.  It  is  coagulated  also  by  the  juices  of  the  stomach. 
It  is  important  as  an  article  of  food,  being  the  principal  organic  in- 
gredient in  all  the  preparations  of  milk.  In  a  coagulated  form,  it 
constitutes  the  different  varieties  of  cheese,  which  are  more  or  less 
highly  flavored  with  various  oily  matters  remaining  entangled  in 
the  coagulated  casein. 


GLOBULINE. — MUCOSINE.  69 

What  is  called  vegetable  casein  or  "legumine,"  is  different  from 
the  casein  of  milk,  and  constitutes  the  organic  substance  present  in 
various  kinds  of  peas  and  beans. 

4.  Globuline. — This  is  the  organic  substance  forming  the  prin- 
cipal mass  of  the  red  globules  of  the  blood.  It  is  nearly  fluid  in 
its  natural  condition,  and  readily  dissolves  in  water.  It  does  not 
dissolve,  however,  in  the  serum  of  the  blood;  and  the  globules, 
therefore,  retain  their  natural  form  and  consistency,  unless  the 
serum  be  diluted  with  an  excess  of  water,  Globuline  resembles 
albumen  in  coagulating  at  the  temperature  of  boiling  water.  It  is 
said  to  differ  from  it,  however,  in  not  being  coagulated  by  contact 
with  alcohol. 

5.  Pepsine. — This  substance  occurs  as  an  ingredient  in  the 
gastric  juice.  It  is  not  the  same  with  the  substance  which  Schwann 
extracted  by  maceration  from  the  mucous  membrane  of  the  stomach, 
and  which  is  regarded  by  Kobin,  Bernard,  &c.,  as  only  an  artificial 
product  of  the  alteration  of  the  gastric  tissues.  There  seems  no 
good  reason,  furthermore,  why  we  should  not  designate  by  this 
name  the  organic  substance  which  really  does  exist  in  the  gastric 
juice.  It  occurs  in  this  fluid  in  very  small  quantity,  not  over 
fifteen  parts  per  thousand.  It  is  coagulable  by  heat,  and  also  by 
contact  with  alcohol.  But  if  the  alcoholic  coagulum  be  well 
washed,  it  is  again  soluble  in  a  watery  acidulated  fluid. 

6.  Panceeatine. — This  is  the  organic  substance  of  the  pancreatic 
juice,  where  it  occurs  in  great  abundance.  It  coagulates  by  heat, 
and  by  contact  with  sulphate  of  magnesia  in  excess.  In  its  natural 
condition  it  is  fluid,  but  has  a  considerable  degree  of  viscidity. 

7.  MucosiNE  is  the  organic  substance  which  is  found  in  the  dif- 
ferent varieties  of  mucus,  and  which  imparts  to  them  their  viscidity 
and  other  physical  characters.  Some  of  these  mucous  secretions 
are  so  mixed  with  other  fluids,  that  their  consistency  is  more  or  less 
diminished ;  others  which  remain  pure,  like  that  secreted  by  the 
mucous  follicles  of  the  cervix  uteri,  have  nearly  a  semi-solid  con- 
sistency. But  little  is  known  with  regard  to  their  other  specific 
characters. 

The  next  three  organic  substances  are  solid  or  semi-solid  in  con- 
sistency. 


70  PKOXIMATE    PEINCIPLES    OF    THE    THIRD    CLASS. 

8.  OSTEINE  is  the  organic  substance  of  the  bones,  in  which  it  is 
associated  with  a  large  proportion  of  phosphate  of  lime.  It  exists, 
in  those  bones  which  have  been  examined,  in  the  proportion  of 
about  two  hundred  parts  per  thousand.  It  is  this  substance  which 
by  long  boiling  of  the  bones  is  transformed  into  gelatine  or  glue. 
In  its  natural  condition,  however,  it  is  insoluble  in  water,  even  at 
the  boiling  temperature,  and  becomes  soluble  only  after  it  has  been 
permanently  altered  by  ebullition. 

9.  Cartilagine. — This  forms  the  organic  ingredient  of  cartilage. 
Like  that  of  the  bones,  it  is  altered  by  long  boiling,  and  is  converted 
into  a  peculiar  kind  of  gelatine  termed  "  chondrine."  Chondrine 
differs  from  the  gelatine  of  bones  principally  in  being  precipitated 
by  acids  and  certain  metallic  salts  which  have  no  effect  on  the 
latter.  Cartilagine,  in  its  natural  condition,  is  very  solid,  and  is 
closely  united  with  the  calcareous  salts. 

10.  MuscuLiNE. — This  substance  forms  the  principal  mass  of  the 
muscular  fibre.  It  is  semi-solid,  and  insoluble  in  water,  but  soluble 
in  dilute  muriatic  acid,  from  which  it  may  be  again  precipitated  by 
neutralizing  with  an  alkali.  It  closely  resembles  albumen  in  its 
chemical  composition,  and  like  it,  contains,  according  to  Scherer, 
two  equivalents  of  sulphur. 

The  four  remaining  organic  substances  form  a  somewhat  peculiar 
group,  Tliey  are  the  coloring  matters  of  the  body.  They  exist 
always  in  small  quantity,  compared  with  the  other  ingredients,  but 
communicate  to  the  tissues  and  fluids  a  very  distinct  coloration. 
They  all  contain  iron  as  one  of  their  ultimate  elements. 

11.  H^matine  is  the  coloring  matter  of  the  red  globules  of  the 
blood.  It  is  nearly  fluid  like  the  globuline,  and  is  united  with  it 
in  a  kind  of  mutual  solution.  It  is  much  less  abundant  than  the 
globuline,  and  exists  in  the  proportion  of  about  one  part  of  hsema- 
tine  to  seventeen  parts  of  globuline.  The  following  is  the  formula 
for  its  composition  which  is  adopted  by  Lehmann : — 

Hsematine ^  C44H22N30gFe. 

When  the  blood-globules  from  any  cause  become  disintegrated, 
the  hsematine  is  readily  imbibed  after  death  by  the  walls  of  the 
bloodvessels  and  the  neighboring  parts,  staining  them  of  a  deep  red 
color.    This  coloration  has  sometimes  been  mistaken  for  an  evidence 


MELANIJSTE. — UEOSACINE.  71 

of  arteritis ;  but  is  really  a  simple  effect  of  post-mortem  imbibition, 
as  above  stated. 

12.  Melanine. — This  is  the  blackish-brown  coloring  matter 
which  is  found  in  the  choroid  coat  of  the  eye,  the  iris,  the  hair,  and 
more  or  less  abundantly  in  the  epidermis.  So  far  as  can  be  ascer- 
tained, the  coloring  matter  is  the  same  in  all  these  situations.  It  is 
very  abundant  in  the  black  and  brown  races,  less  so  in  the  yellow 
and  white,  but  is  present  to  a  certain  extent  in  all.  Even  where 
the  tinges  produced  are  entirely  different,  as,  for  example,  in  brown 
and  blue  eyes,  the  coloring  matter  appears  to  be  the  same  in  cha- 
racter, and  to  vary  only  in  its  quantity  and  the  mode  of  its  arrange- 
ment ;  for  the  tinge  of  an  animal  tissue  does  not  depend  on  its 
local  pigment  only,  but  also  on  the  muscular  fibres,  fibres  of  areolar 
tissue,  capillary  bloodvessels,  &c.  All  these  ingredients  of  the* 
tissue  are  partially  transparent,  and  by  their  mutual  interlacement 
and  superposition  modify  more  or  less  the  effect  of  the  pigment 
which  is  deposited  below  or  among  them. 

Melanine  is  insoluble  in  water  and  the  dilute  acids,  but  dissolves 
slowly  in  caustic  potass.  Its  ultimate  composition  resembles  that 
of  hsematine,  but  the  proportion  of  iron  is  smaller.  ^ 

13.  BiLiVERDiNE  is  the  coloring  matter  of  the  bile.  It  is  yellow 
by  transmitted  light,  greenish  by  reflected  light.  On  exposure  to 
the  air  in  its  natural  fluid  condition,  it  absorbs  oxygen  and  assumes 
a  bright  grass  green  color.  The  same  effect  is  produced  by  treating 
it  with  nitric  acid  or  other  oxidizing  substances.  It  occurs  in  very 
small  quantity  in  the  bile,  from  which  it  may  be  extracted  by  pre- 
cipitating it  with  milk  of  lime  (Robin),  from  which  it  is  afterward 
separated  by  dissolving  out  the  lime  with  muriatic  acid.  Obtained 
in  this  form,  however,  it  is  insoluble  in  water,  having  been  coagu- 
lated by  contact  with  the  calcareous  matter;  and  is  not,  therefore, 
precisely  in  its  original  condition. 

14.  Ubosacine  is  the  yellowish-red  coloring  matter  of  the  urine. 
It  consists  of  the  same  ultimate  elements  as  the  other  coloring  mat- 
ters, but  occurs  in  the  urine  in  such  minute  quantity,  that  the 
relative  proportion  of  its  elements  has  never  been  determined.  It 
readily  adheres  to  insoluble  matters  when  they  are  precipitated  from 
the  urine,  and  is  consequently  found  almost  always,  to  a  greater  or 
less  extent,  as  an  ingredient  in  urinary  calculi  formed  of  the  urates 


72  PEOXIMATE    PEINCIPLES    OF    THE    THIKD    CLASS. 

or  of  uric  acid.  When  tlie  urates  are  thrown  down  also  in  the  form 
of  a  powder,  as  a  urinary  deposit,  they  are  usually  colored  more  or 
less  deeply,  according  to  the  quantity  of  urosacine  which  is  preci- 
pitated with  them. 

The  organic  substances  which  exist  in  the  body  require  for  their 
production  an  abundant  supply  of  similar  substances  in  the  food. 
All  highly  nutritious  articles  of  diet,  therefore,  contain  more  or  less 
of  these  substances.  Still,  though  nitrogenous  matters  must  be 
abundantly  supplied,  under  some  form,  from  without,  yet  the  par- 
ticular kinds  of  organic  substances,  characteristic  of  the  tissues,  are 
formed  in  the  body  by  a  transformation  of  those  which  are  intro- 
duced with  the  food.  The  organic  matters  derived  from  vegetables, 
though  similar  in  their  general  characters  to  those  existing  in  the 
animal  body,  are  yet  specifically  different.  The  gluten  of  wheat, 
th/e  legumine  of  peas  and  beans,  are  not  the  same  with  animal  al- 
bumen and  fibrin.  The  only  organic  substances  taken  with  animal 
food,  as  a  general  rule,  are  the  albumen  of  eggs,  the  casein  of  milk, 
and  the  musculine  of  flesh ;  and  even  these,  in  the  food  of  the 
human  species,  are  so  altered  and  coagulated  by  the  process  of 
cooking,  as  to  lose  their  specific  characters  before  being  introduced 
into  the  alimentary  canal.  They  are  still  further  changed  by  the 
process  of  digestion,  and  are  absorbed  under  another  form  into  the 
blood.  But  from  their,  subsequent  metamorphoses  there  are  formed, 
in  the  different  parts  of  the  body,  osteine,  cartilagine,  haematine, 
globuline,  and  all  the  other  varieties  of  organic  matter  that  cha- 
racterize the  different  tissues.  These  varieties,  therefore,  originate 
as  such  in  the  animal  economy  by  the  catalytic  changes  which  the 
ingredients  of  the  blood  undergo  in  nutrition. 

Only  a  very  small  quantity  of  organic  matter  is  discharged 
with  the  excretions.  The  coloring  matters  of  the  bile  and  urine, 
and  the  mucus  of  the  urinary  bladder,  are  almost  the  only  ones 
that  find  an  exit  from  the  body  in  this  way.  There  is  a  minute 
quantity  of  organic  matter  exhaled  in  a  volatile  form  with  the 
breath,  and  a  little  also,  in  all  probability,  from  the  cutaneous  sur- 
face. But  the  entire  quantity  so  discharged  bears  but  a  very  small 
proportion  to  that  which  is  daily  introduced  with  the  food.  The 
organic  substances,  therefore,  are  decomposed  in  the  interior  of  the 
body.  They  are  transformed  by  the  process  of  destructive  assimi- 
lation, and  their  elements  are  finally  eliminated  and  discharged 
under  other  forms  of  combination. 


OF    FOOD.  73 


CHAPTER    V. 

OF   FOOD. 

Under  the  term  "  food"  are  included  all  those  substances,  solid 
and  liquid,  which  are  necessary  to  sustain  the  process  of  nutrition. 
The  first  act  of  this  process  is  the  absorption  from  without  of  all 
those  materials  which  enter  into  the  composition  of  the  living 
frame,  or  of  others  which  may  be  converted  into  them  in  the  in- 
terior of  the  body. 

The  proximate  principles  of  the  first  class,  or  the  "inorganic 
substances,"  require  to  be  supplied  in  sufficient  quantity  to  keep  up 
the  natural  proportion  in  which  they  exist  in  the  various  solids  and 
fluids.  As  we  have  found  it  to  be  characteristic  of  these  substances, 
except  in  a  few  instances,  that  they  suffer  no  alteration  in  the  in- 
terior of  the  body,  but,- on  the  contrary,  are  absorbed,  deposited  in 
its  tissue,  and  pass  out  of  it  afterward  unchanged,  nearly  every 
one  of  them  requires  to  be  present  under  its  own  proper  form,  and 
in  sufficient  quantity  in  the  food.  The  alkaline  carbonates,  which 
a,re  formed,  as  we  have  seen,  by  a  decomposition  of  the  malates, 
citrates  and  tartrates,  constitute  almost  the  only  exception  to  this 
rule. 

Since  water  enters  so  largely  into  the  composition  of  nearly  every 
part  of  the  body,  it  is  equally  important  as  an  ingredient  of  the 
food.  In  the  case  of  the  human  subject,  it  is  probably  the  most 
important  substance  to  be  supplied  with  constancy  and  regularity, 
and  the  system  suffers  more  rapidly  when  entirely  deprived  of 
fluids,  than  when  the  supply  of  solid  food  only  is  withdrawn.  A 
man  may  pass  eight  or  ten  hours,  for  example,  without  solid  food, 
and  suffer  little  or  no  inconvenience ;  but  if  deprived  of  water  for 
the  same  length  of  time,  he  becomes  rapidly  exhausted,  and  feels 
the  deficiency  in  a  very  marked  degree.  Magendie  found,  in  his 
experiments  on  dogs  subjected  to  inanition,^  that  if  the  animals 

'  Comptes  Rendus,  vol.  xiii.  p.  256. 


74  OF    FOOD. 

were  supplied  with  water  alone  they  lived  six,  eight,  and  even  ten 
days  longer  than  if  they  were  deprived  at  the  same  time  of  both 
solid  and  liquid  food.  Chloride  of  sodium,  also,  is  usually  added 
to  the  food  in  considerable  quantity,  and  requires  to  be  supplied 
with  tolerable  regularity ;  but  the  remaining  inorganic  materials, 
such  as  calcareous  salts,  the  alkaline  phosphates,  &c.,  occur  natu- 
rally in  sufficient  quantity  in  most  of  the  articles  which  are  used  as 
food. 

The  proximate  principles  of  the  second  class,  so  far  as  they  con- 
stitute ingredients  of  the  food,  are  naturally  divided  into  two 
groups :  1st,  the  sugar,  and  2d,  the  oily  matters.  Since  starch  is 
always  converted  into  sugar  in  the  process  of  digestion,  it  may  be 
included,  as  an  alimentary  substance,  in  the  same  group  with  the 
sugars.  There  is  a  natural  desire  in  the  human  species  for  both 
saccharine  and  oleaginous  food.  In  the  purely  carnivorous  animals, 
however,  though  no  starch  or  sugar  be  taken,  yet  the  body  is  main- 
tained in  a  healthy  condition.  It  has  been  supposed,  therefore,  that 
saccharine  matters  could  not  be  absolutely  necessary  as  food ;  the 
more  so  since  it  has  been  found,  by  the  experiments  of  CI.  Bernard, 
that,  in  carnivorous  animals  kept  exclusively  on  a  diet  of  flesh, 
sugar  is  still  formed  in  the  liver,  as  well  as  in  the  mammary  gland. 
The  above  conclusion,  however,  which  has  been  drawn  from  these 
facts,  does  not  apply  practically  to  the  human  species.  The  car- 
nivorous animals  have  no  desire  for  vegetable  food,  while  in  the 
human  species  there  is  a  natural  craving  for  it,  which  is  almost 
universal.  It  may  be  dispensed  with  for  a  few  days,  but  not  with 
impunity  for  any  great  length  of  time.  The  experiment  has  often 
enough  been  tried,  in  the  treatment  of  diabetes,  of  confining  the 
patient  to  a  strictly  animal  diet.  It  has  been  invariably  found 
that,  if  this  regimen  be  continued  for  some  weeks,  the  desire  for 
vegetable  food  on  the  part  of  the  patient  becomes  so  imperative 
that  the  plan  of  treatment  is  U-navoidably  abandoned. 

A  similar  question  has  also  arisen  with  regard  to  the  oleaginous 
matters.  Are  these  substances  indispensable  as  ingredients  of  the 
food,  or  may  they  be  replaced  by  other  proximate  principles,  such 
as  starch  or  sugar?  It  has  already  been  seen,  from  the  experiments 
of  Boussingault  and  others,  that  a  certain  amount  of  fat  is  produced 
in  the  body  over  and  above  that  which  is  taken  with  the  food ;  and 
it  appears  also  that  a  regimen  abounding  in  saccharine  substances 
is  favorable  to  the  production  of  fat.  It  is  altogether  probable, 
therefore,  that   the  materials  for  the  production  of  fat  may  be 


OF    FOOD.  70 

derived,  under  these  cii'cumstances,  either  directly  or  indirectly 
from  saccharine  matters.  But  saccharine  matters  alone  are  not 
entirely  sufficient.  M.  Huber'  thought  he  had  demonstrated  that 
bees  fed  on  pure  sugar  would  produce  enough  wax  to  show  that 
the  sugar  could  supply  all  that  was  necessary  to  the  formation  of 
the  fatty  matter  of  the  wax.  Dumas  and  Milne-Edwards,  however, 
in  repeating  Huber's  experiments,^  found  that  this  was  not  the  case. 
Bees,  fed  on  pure  sugar,  soon  cease  to  work,  and  sometimes  perish 
in  considerable  numbers ;  but  if  fed  with  honey,  which  contains 
some  v/axy  and  other  matters  beside  the  sugar,  they  thrive  upon 
it;  and  produce,  in  a  given  time,  a  much  larger  quantity  of  fat  than 
was  contained  in  the  whole  supply  of  food. 

The  same  thing  was  established  by  Boussingault  with  regard  to 
starchy  matters.  He  found  that  in  fattening  pigs,  though  the 
quantity  of  fat  accumulated  by  the  animal  considerably  exceeded 
that  contained  in  the  food,  yet  fat  must  enter  to  some  extent  into 
the  composition  of  the  food  in  order  to  maintain  the  animals  in  a 
good  condition ;  for  pigs,  fed  on  boiled  potatoes  alone  (an  article 
abounding  in  starch  but  nearly  destitute  of  oily  matter),  fattened 
slowly  and  with  great  difficulty ;  while  those  fed  on  potatoes  mixed 
with  a  greasy  flaid  fattened  readily,  and  accumulated,  as  mentioned 
above,  much  more  fat  than  was  contained  in  the  food. 

The  apparent  discrepancy  between  these  facts  may  be  easily  ex- 
plained, when  we  recollect  that,  in  order  that  the  animal  may  become 
fattened,  it  is  necessary  that  he  be  supplied  not  only  with  the 
materials  of  the  fat  itself,  but  also  with  everything  else  which  is 
necessary  to  maintain  the  body  in  a  healthy  condition.  Oleaginous 
matter  is  one  of  these  necessary  substances.  The  fats  which  are 
taken  in  with  the  food  are  not  destined  to  be  simply  transported 
into  the  body  and  deposited  there  unchanged.  On  the  contrary, 
they  are  altered  and  used  up  in  the  processes  of  digestion  and 
nutrition ;  while  the  fats  which  appear  in  the  body  as  constituents 
of  the  tissues  are,  in  great  part,  of  new  formation,  and  are  produced 
from  materials  derived,  perhaps,  from  a  variety  of  different  sources. 

It  is  certain,  then,  that  either  one  or  the  other  of  these  two 
groups  of  substances,  saccharine  or  oleaginous,  must  enter  into  the 
composition  of  the  food;  and  furthermore,  that,  though  the  oily 
matters  may  sometimes  be  produced  in  the  body  from  the  sugars, 

'  Natural  History  of  Bees,  Edinboro',  1821,  p.  330. 

^  Aimales  de  Chim.  et  de  Phys.,  3d  series,  vol.  xiv.  p.  400. 


76  OF    FOOD. 

it  is  also  necessary  for  the  perfect  nutrition  of  the  body  that  fat  be 
supplied,  under  its  own  form,  with  the  food.  For  the  human 
species,  also,  it  is  natural  to  have  them  both  associated  in  the 
alimentary  materials.  They  occur  together  in  most  vegetable  sub- 
stances, and  there  is  a  natural  desire  for  them  both,  as  elements 
of  the  food. 

They  are  not,  however,  when  alone,  or  even  associated  with  each 
other,  sufficient  for  the  nutrition  of  the  animal  body.  Magendie 
found  that  dogs,  fed  exclusively  on  starch  or  sugar,  perished  after  a 
short  time  with  symptoms  of  profound  disturbance  of  the  nutritive 
functions.  An  exclusive  diet  of  butter  or  lard  had  a  similar  effect. 
The  animal  became  exceedingly  debilitated,  though  without  much 
emaciation ;  and  after  death,  all  the  internal  organs  and  tissues 
were  found  infiltrated  with  oil.  Boussingault'  performed  a  similar 
experiment,  with  a  like  result,  upon  a  duck,  which  was  kept  upon 
an  exclusive  regimen  of  butter.  "  The  duck  received  1350  to  1500 
grains  of  butter  every  day.  At  the  end  of  three  weeks  it  died  of 
inanition.  The  butter  oozed  from  every  part  of  its  body.  The 
feathers  looked  as  though  they  had  been  steeped  in  melted  butter, 
and  the  body  exhaled  an  unwholesome  odor  like  that  of  butyric 
acid." 

Lehmann  was  also  led  to  the  same  result  by  some  experiments 
which  he  performed  upon  himself  for  the  purpose  of  ascertaining 
the  effect  produced  on  the  urine  by  different  kinds  of  food.^ 
This  observer  confined  himself  first  to  a  purely  animal  diet  for 
three  weeks,  and  afterwards  to  a  purely  vegetable  one  for  sixteen 
days,  without  suffering  any  marked  inconvenience.  He  then  put 
himself  upon  a  regimen  consisting  entirely  of  non-nitrogenous  sub- 
stances, starch,  sugar,  gum,  and  oil,  but  was  only  able  to  continue 
this  diet  for  two,  or  at  most  for  three  days,  owing  to  the  marked 
disturbance  of  the  general  health  which  rapidly  supervened.  The 
unpleasant  symptoms,  however,  immediately  disappeared  on  his 
return  to  an  ordinary  mixed  diet.  The  same  fact  has  been  esta- 
blished more  recently  by  Dr.  Wm.  A.  Hammond,  Assistant  Surgeon 
U.  S.  Army,^  in  a  series  of  experiments  which  he  performed  upon 
himself.  He  was  enabled  to  live  for  ten  days  on  a  diet  composed 
exclusively  of  boiled  starch  and  water.     After  the  third  day,  how- 

■  Chimie  Agricole,  p.  166. 

^  Journal  fiir  praktische  Chemie,  vol.  xxvii.  p.  257. 

*  Experimental  Researches,  &c.,  being  the  Prize  Essay  of  the  American  Medical 
Association  for  1857. 


OF    FOOD.  77 

ever,  the  general  health  began  to  deteriorate,  and  became  verj  much 
disturbed  before  the  termination  of  the  experiment.  The  prominent 
symptoms  were  debility,  headache,  pyrosis,  and  palpitation  of  the 
heart.  After  the  starchy  diet  was  abandoned,  it  required  some 
days  to  restore  the  health  to  its  usual  condition. 

The  proximate  principles  of  the  third  class,  or  the  organic  sub- 
stances proper,  enter  so  largely  into  the  constitution  of  the  animal 
tissues  and  fluids,  that  their  importance,  as  elements  of  the  food,  is 
easily  understood.  No  food  can  be  long  nutritious,  unless  a  certain 
proportion  of  these  substances  be  present  in  it.  Since  they  are  so 
abundant  as  ingredients  of  the  body,  their  loss  or  absence  from  the 
food  is  felt  more  speedily  and  promptly  than  that  of  any  other  sub- 
stance except  water.  They  have,  therefore,  sometimes  received  the 
name  of  "  nutritious  substances,"  in  cbntradistinction  to  those  of 
the  second  class,  which  contain  no  nitrogen,  and  which  have  been 
found  by  the  experiments  of  Magendie  and  others  to  be  insufficient 
for  the  support  of  life.  The  organic  substances,  however,  when 
taken  alone,  are  no  more  capable  of  supporting  life  indefinitely  than 
the  others.  It  was  found  in  the  experiments  of  the  French  "  Gela- 
tine Commission"^  that  animals  fed  on  pure  fibrin  and  albumen,  as 
well  as  those  fed  on  gelatine,  become  after  a  short  time  much  en- 
feebled, refuse  the  food  which  is  offered  to  them,  or  take  it  with 
reluctance,  and  finally  die  of  inanition.  This  result  has  been  ex- 
plained by  supposing  that  these  substances,  when  taken  alone, 
excite  after  a  time  such  disgust  in  the  animal  that  they  are  either 
no  longer  taken,  or  if  taken  are  not  digested.  But  this  diso-ust 
itself  is  simply  an  indication  that  the  substances  used  are  insufficient 
and  finally  useless  as  articles  of  food,  and  that  the  system  demands 
instinctively  other  materials  for  its  nourishment. 

The  instinctive  desire  of  animals  for  certain  substances  is  the 
surest  indication  that  they  are  in  reality  required  for  the  nutritive 
process ;  and  on  the  other  hand,  the  indifference  or  repugnance 
manifested  for  injurious  or  useless  substances,  is  an  equal  evidence 
of  their  unfitness  as  articles  of  food.  This  repugnance  is  well  de- 
scribed by  Magendie,  in  the  report  of  the  commission  above  alluded 
to,  while  detailing  the  result  of  his  investigations  on  the  nutritive 
qualities  of  gelatine.  "  The  result,"  he  says,  "  of  these  first  trials 
was  that  pure  gelatine  was  not  to  the  taste  of  the  dogs  experimented 
on.     Some  of  them  suffered  the  pangs  of  hunger  with  the  gelatine 

'  Comptes  Eendus,  1841,  vol.  xiii.  p.  267. 


78  OF    FOOD. 

within  their  reach,  and  would  not  touch  it ;  others  tasted  of  it,  but 
wjould  not  eat:  others  still  devoured  a  certain  quantity  of  it  once 
or  twice,  and  then  obstinately  refused  to  make  any  farther  use  of  it." 

In  one  instance,  however,  Magendie  succeeded  in  inducing  a  dog 
to  take  a  considerable  quantity  of  pure  fibrin  daily  throughout  the 
whole  course  of  the  experiment;  but  notwithstanding  this,  the 
animal  became  emaciated  like  the  others,  and  died  at  last  with  the 
same  symptoms  of  inanition. 

The  alimentary  substances  of  the  second  class,  however,  viz.,  the 
sugars  and  the  oils,  have  been  sometimes  thought  less  important 
than  the  albuminous  matters,  because  they  do  not  enter  so  largely 
or  so  permanently  into  the  composition  of  the  solid  tissues.  The 
saccharine  matters,  when  taken  as  food,  cannot  be  traced  farther 
than  the  blood.  They  undergo  already,  in  the  circulating  fluid, 
some  change  by  which  their  essential  character  is  lost,  and  they 
cannot  be  any  longer  recognized.  The  appearance  of  sugar  in  the 
mammary  gland  and  the  milk  is  only  exceptional,  and  does  not 
occur  at  all  in  the  male  subject.  The  fats  are,  it  is  true,  very  gene- 
rally distributed  throughout  the  body,  but  it  is  only  in  the  brain 
and  nervous  matter  that  they  exist  intimately  united  with  thie  re- 
maining ingredients  of  the  tissues.  Elsewhere,  as  already  mentioned, 
it  is  deposited  in  distinct  drops  and  granules,  and  so  long  as  it  re- 
mains in  this  condition  must  of  course  remain  inactive,  so  far  as 
reo-ards  any  chemical  nutritive  process.  In  this  condition  it  seems 
to  be  held  in  reserve,  ready  to  be  absorbed  by  the  blood,  whenever 
it  may  be  required  for  the  purposes  of  nutrition.  On  being  reab- 
sorbed, however,  as  soon  as  it  again  enters  the  blood  or  unites 
intimately  with  the  substance  of  the  tissues,  it  at  once  changes  its 
condition  and  loses  its  former  chemical  constitution  and  properties. 

It  is  for  these  reasons  that  the  albuminoid  matters  have  been 
sometimes  considered  as  the  only  "  nutritious"  substances,  because 
they  alone  constitute  under  their  own  form  a  great  part  of  the 
ingredients  of  the  tissues,  while  the  sugars  and  the  oils  rapidly  dis- 
appear by  decomposition.  It  has  even  been  assumed  that  the  pro- 
cess by  which  the  sugar  and  the  oils  disappear  is  one  of  direct 
combustion  or  oxidation,  and  that  they  are  destined  solely  to  be 
consumed  in  this  way,  not  to  enter  at  all  into  the  composition  of 
tlie  tissues,  but  only  to  maintain  the  heat  of  the  body  by  an  inces- 
sant process  of  combustion  in  the  blood.  They  have  been  therefore 
termed  the  "  combustible"  or  "  heat-producing"  elements,  while  the 


OF    FOOD.  79 

albuminoid  substances  were  known  as  the  nutritious  or  "plastic" 
elements. 

This  distinction,  however,  has  no  real  foundation.  In  the  first 
place,  it  is  not  at  all  certain  that  the  sugars  and  the  oils  which  dis- 
appear in  the  body  are  destroyed  by  combustion.  This  is  merely 
an  inference  which  has  been  made  without  any  direct  proof.  All 
we  know  positivel}^  in  regard  to  the  matter  is  that  these  substances 
soon  become  so  altered  in  the  blood  that  they  can  no  longer  be 
recognized  by  their  ordinary  chemical  properties ;  but  we  are  still 
ignorant  of  the  exact  nature  of  the  transformations  which  they 
undergo.  Furthermore,  the  difference  between  the  sugars  and  the 
oils  on  the  one  hand,  and  the  albuminoid  substances  on  the  other, 
so  far  as  regards  their  decomposition  and  disappearance  in  the  body, 
is  only  a  difference  of  time.  The  albuminoid  substances  become 
transformed  more  slowly,  the  sugars  and  the  oils  more  rapidly. 
Even  if  it  should  be  ascertained  hereafter  that  the  sugars  and  the 
oils  really  do  not  unite  at  all  with  the  solid  tissues,  but  are  entirely 
decomposed  in  the  blood,  this  would  not  make  them  any  less  im- 
portant as  alimentary  substances,  since  the  blood  is  as  essential  a 
part  of  .the  body  as  the  solid  tissues,  and  its  nutrition  must  be  pro- 
vided for  equally  with  theirs. 

It  is  evident,  therefore,  that  no  single  proximate  principle,  nor 
even  any  one  class  of  them  alone,  can  be  sufficient  for  the  nutrition 
of  the  body;  but  that  the  food,  to  be  nourishing,  must  contain 
substances  belonging  to  all  the  different  groups  of  proximate  prin- 
ciples. The  albuminoid  substances  are  first  in  importance  because 
they  constitute  the  largest  part  of  the  entire  mass  of  the  body ;  and 
exhaustion  therefore  follows  more  rapidly  when  they  are  withheld 
than  when  the  animal  is  deprived  of  other  kinds  of  alimentary 
matter.  But  starchy  and  oleaginous  substances  are  also  requisite ; 
and  the  body  feels  the  want  of  them  sooner  or  later,  though  it  may 
be  plentifully  supplied  with  albumen  and  fibrin.  Finally,  the  in- 
organic saline  matters,  though  in  smaller  quantity,  are  also  neces- 
sary to  the  continuous  maintenance  of  life.  In  order  that  the 
animal  tissues  and  fluids  remain  in  a  healthy  condition  and  take 
their  proper  part  in  the  functions  of  life,  they  must  be  supplied 
with  all  the  ingredients  necessary  to  their  constitution ;  and  a  man 
may  be  starved  to  death  at  last  by  depriving  him  of  chloride  of 
sodium  or  phosphate  of  lime  just  as  surely,  though  not  so  rapidly, 
as  if  he  were  deprived  of  albumen  or  oil. 

In  the  different  kinds  of  food,  accordingly,  which  have  been 


80  OF    FOOL*. 

adopted  by  the  universal  and  instinctive  cTioice  of  man,  the  three 
different  classes  of  proximate  principles  are  all  more  or  less  abund- 
antly represented.  In  all  of  them  there  exists  naturally  a  certain 
proportion  of  saline  substances ;  and  water  and  chloride  of  sodium 
are  gefnerally  taken  with  them  in  addition.  In  milk,  the  first  food 
supplied  to  the  infant,  we  have  casein  which  is  an  albuminoid 
substance,  butter  which  represents  the  oily  matters,  and  sugar  of 
milk  belonging  to  the  saccharine  group,  together  with  water  and 
saline  matters,  in  the  following  proportions : — ^ 

Composition  of  Cow's  Milk. 

Water 87.02 

Casein '     .         .         .      4.48 

Butter  .         .         .         .         , 3.13 

Sugar  of  milk 4.77 

Soda 1 

Chlorides  of  potassium  and  sodium      ..... 

Phosphates  of  soda  and  potass 

Phosphate  of  lime         • •         .1-0.60 

"  magnesia  .         . 

Alkaline  carbonates       .         .         .         . 

Iron,  &c.        .         .         .   ■      .         ■         •         •         •         •         • 

100.00 

In  wheat  flour,  gluten  is  the  albuminoid  matter,  sugar  and  starch 
the  non-nitrogenous  principles. 


Composition  of  Wheat  Flouk. 

Gluten  . 

.       10.2                Gum       . 

2.8 

Starch    . 

.       72.8                Water    . 
4.2 

.       10.0 

Sugar     . 

100.0 

The  other  cereal  grains  mostly  contain  oil  in  addition  to  the 
above. 

Composition  op  Dkied  Oatmeal. 

Starch 59.00 

Bitter  matter  and  sugar 8.25 

Gray  albuminous  matter 4.30 

Fatty  oil 2.00 

Gum •  2.50 

Husk,  mixture,  and  loss 23.95 

100.00 
Eggs  contain  albumen  and  salts  in  the  white,  with  the  addition 
of  oily  matter  in  the  yolk. 

*  The  accompanying  analyses  of  various  kinds  of  food  are  taken  from  Pereira 
on  Food  and  Diet,  New  York,  1843. 


OF    FOOD.  81 

Composition  of  Eggs. 

White  of  Egg.  Yolk  of  Egg. 

Water  ....       80.00 53.78 

Albumen  and  mucus     .       15.28 12.75 

Yellow  oil     ...  28.75 

Salts     ....        4.72 4.72 

100.00  100.00 

In  ordinary  flesh   or  butcher's  meat,  we  have  the  albuminoid 

matter  of  the  muscular  fibre  and  the  fat  of  the  adipose  tissue. 

Composition  of  Ordinary  Butcher's  Meat. 

Meat  devoid  of  fat         .       85.7  |  ^^^^^    ....       63.418 

I  Solid  matter  .         .         .       22.282 
Fat,  cellular  tissue,  &c 14.300 

100.000 

From  what  has  been  said  above,  it  will  easily  be  seen  that  the 
nutritious  character  of  any  substance,  or  its  value  as  an  article  of 
food,  does  not  depend  simply  upon  its  containing  either  one  of  the 
alimentary  substances  mentioned  above  in  large  quantity ;  but  upon 
its  containing  them  mingled  together  in  such  proportion  as  is 
requisite  for  the  healthy  nutrition  of  the  body.  What  these  pro- 
portions are  cannot  be  determined  from  simple  chemical  analysis, 
nor  from  any  other  data  than  those  derived  from  direct  observation 
and  experiment. 

The  total  quantity  of  food  required  by  man  has ,  been  variously 
estimated.  It  will  necessarily  vary,  indeed,  not  only  with  the  con- 
stitution and  habits  of  the  individual,  but  also  with  the  quality  of 
the  food  employed ;  since  some  articles,  such  as  corn  and  meat,  con- 
tain very  much  more  alimentary  material  in  the  same  bulk  than 
fresh  fruits  or  vegetables.  Any  estimate,  therefore,  of  the  total 
quantity  should  state  also  the  kind  of  food  used ;  otherwise,  it  will 
be  altogether  without  value.  From  experiments  performed  while 
living  on  an  exclusive  diet  of  bread,  fresh  meat,  and  butter,  witb 
coffee  and  water  for  drink,  we  have  found  that  the  entire  quantity 
of  food  required  during  twenty-four  hours  by  a  man  in  full  health, 
and  taking  free  exercise  in  the  open  air,  is  as  follows : — 

Meat 16  ounces. 

Bread  .         .         .         .     , 19       " 

Butter 3^      " 

Fluids 52        " 

That  is  to  say,  rather  less  than  two  and  a  half  pounds  of  solid  food, 
and  rather  over  three  pints  of  liquid  food. 
6 


82  OF    FOOD. 

Another  necessary  consideration,  in  estimating  the  value  of  any 
substance  as  an  article  of  food,  is  its  digestibility.  A  vegetable  or 
animal  tissue  may  contain  an  abundance  of  albuminoid  or  starchy 
matter,  but  may  be  at  the  same  time  of  such  an  unyielding  consist- 
ency as  to  be  insoluble  in  the  digestive  fluids,  and  therefore  useless 
as  an  article  of  food.  Bones  and  cartilages,  and  the  fibres  of  yel- 
low elastic  tissue,  are  indigestible,  and  therefore  not  nutritious. 
The  same  remark  may  be  made  with  regard  to  the  substances  con- 
tained in  woody  fibre,  and  the  hard  coverings  and  kernels  of  various 
fruits.  Everything,  accordingly,  which  softens  or  disintegrates  a 
hard  alimentary  substance  renders  it  more  digestible,  and  so  far 
increases  its  value  as  an  article  of  food. 

The  preparation  of  food  by  cooking  has  a  twofold  object :  first, 
to  soften  or  disintegrate  it,  and  second,  to  give  it  an  attractive 
flavor.  Many  vegetable  substances  are  so  hard  as  to  be  entirely 
indigestible  in  a  raw  state.  Eipe  peas  and  beans,  the  difierent  kinds 
of  grain,  and  many  roots  and  fruits,  require  to  be  softened  by  boil- 
ing, or  some  other  culinary  process,  before  they  are  ready  for  use. 
With  them,  the  principal  change  produced  by  cooking  is  an  altera- 
tion in  consistency.  With  most  kinds  of  animal  food,  however, 
the  effect  is  somewhat  different.  In  the  case  of  muscular  flesh,  for 
example,  the  muscular  fibres  themselves  are  almost  always  more  or 
less  hardened  by  boiling  or  roasting ;  but,  at  the  same  time,  the 
fibrous  tissue  by  which  they  are  held  together  is  gelatinized  and 
softened,  so  that  the  muscular  fibres  are  more  easily  separated  from 
each  other,  and  more  readily  attacked  by  the  digestive  fluids.  But 
beside  this,  the  organic  substances  contained  in  meat,  which  are  all 
of  them  very  insipid  in  the  raw  state,  acquire,  by  the  action  of  heat 
in  cooking,  a  peculiar  and  agreeable  flavor.  This  flavor  excites 
the  appetite  and  stimulates  the  flow  of  the  digestive  fluids,  and 
renders,  in  this  way,  the  entire  process  of  digestion  more  easy  and 
expeditious. 

The  changes  which  the  food  undergoes  in  the  interior  of  the  body 
may  be  included  under  three  different  heads :  first,  digestion^  or  the 
preparation  of  the  food  in  the  alimentary  canal;  second,  assimila- 
tion^ by  which  the  elements  of  the  food  are  converted  into  the  ani- 
mal tissues ;  and  third,  excretion,  by  which  it  is  again  decomposed, 
and  finally  discharged  from  the  body. 


DIGESTION.  83 


CHAPTER   VI. 

DIGESTION. 

Digestion  is  that  process  by  whicli  the  food  is  reduced  to  a  form 
iu  which  it  can  be  absorbed  from  the  intestinal  canal,  and  taken  up 
by  the  bloodvessels.  This  process  does  not  occur  in  vegetables. 
For  vegetables  are  dependent  for  their  nutrition,  mostly,  if  not 
entirely,  upon  a  supply  of  inorganic  substances,  as  water,  saline 
matters,  carbonic  acid,  and  ammonia.  These  materials  constitute 
the  food  upon  which  plants  subsist,  and  are  converted  in  their  inte- 
rior into  other  substances,  by  the  nutritive  process.  These  mate- 
rials, furthermore,  are  constantly  supplied  to  the  vegetable  under 
such  a  form  as  to  be  readily  absorbed.  Carbonic  acid  and  ammonia 
exist  in  a  gaseous  form  in  the  atmosphere,  and  are  also  to  be  found 
in  solution,  together  with  the  requisiie  saline  matters,  in  the  water 
with  which  the  soil  is  penetrated.  All  these  substances,  therefore, 
are  at  once  ready  for  absorption,  and  do  not  require  any  preliminary 
modification.  But  with  animals  and  man  the  case  is  different. 
They  cannot  subsist  upon  these  inorganic  substances  alone,  but 
require  for  their  support  materials  which  have  already  been  organ- 
ized, and  which  have  previously  constituted  a  part  of  animal  or 
vegetable  bodies.  Their  food  is  almost  nvariably  solid  or  semi-solid 
at  the  time  when  it  is  taken,  and  insoluble  in  water.  Meat,  bread, 
fruits,  vegetables,  &g.,  are  all  taken  into  the  stomach  in  a  solid  and 
insoluble  condition ;  and  even  those  substances  which  are  naturally 
fluid,  such  as  milk,  albumen,  white  of  egg,  are  almost  always, 
in  the  human  species,  coagulated  and  solidified  by  the  process  of 
cooking,  before  being  taken  into  the  stomach. 

In  animals,  accordingly,  the  food  requires  to  undergo  a  process 
of  digestion,  or  liquefaction,  before  it  can  be  absorbed.  In  all  cases, 
the  general  characters  of  this  process  are  the  same.  It  consists 
essentially  in  the  food  being  received  into  a  canal,  running  through 
the  body  from  mouth  to  anus,  called  the  "  alimentary  canal,"  in 
which  it  comes  in  contact  with  certain  digestive  fluids,  which  act 


84.       ,  DIGESTION. 

upon  it  in  such  a  way  as  to  liquefy  and  dissolve  it.  These  fluids 
are  secreted  by  the  mucous  membrane  of  the  alimentary  canal,  and 
by  certain  glandular  organs  situated  in  its  neighborhood.  Since  the 
food  always  consists,  as  we  have  already  seen,  of  a  mixture  of  vari- 
ous substances,  having  different  physical  and  chemical  properties, 
the  several  digestive  fluids  are  also  different  from  each  other ;  each 
one  of  them  exerting  a  peculiar  action,  which  is  more  or  less  con- 
fined to  particular  species  of  food.  As  the  food  passes  through  the 
intestine  from  above  downward,  those  parts  of  it  which  become 
liquefied  are  successively  removed  by  absorption,  and  taken  up  by 
the  vessels ;  while  the  remaining  portions,  consisting  of  the  indiges- 
tible matter,  together  with  the  refuse  of  the  intestinal  secretions, 
gradually  acquire  a  firmer  consistency  owing  to  the  absorption  of 
the  fluids,  and  are  finally  discharged  from  the  intestine  under  the 
form  of  feces. 

In  different  species  of  animals,  however,  the  difference  in  their 
habits,  in  the  constitution  of  their  tissues,  and  in  the  character  of 
their  food,  is  accompanied  with  a  corresponding  variation  in  the 
anatomy  of  the  digestive  apparatus,  and  the  character  of  the  secreted 
fluids.  As  a  general  rule,  the  digestive  apparatus  of  herbivorous 
animals  is  more  complex  than  that  of  the  carnivora ;  since,  in  vege- 
table substances,  the  nutritious  matters  are  often  present  in  a  very 
solid  and  unmanageable  form,  as,  for  example,  in  raw  starch  and 
the  cereal  grains,  and  are  nearly  always  entangled  among  vegetable 
cells  and  fibres  of  an  indigestible  character.  In  those  instances, 
where  the  food  consists  mostly  of  herbage,  as  grass,  leaves,  &c.,  the 
digestible  matters  bear  only  a  small  proportion  to  the  entire  quan- 
tity; and  a  large  mass  of  food  must  therefore  be  taken,  in  order 
that  the  requisite  amount  of  nutritious  material  may  be  extracted 
from  it.  In  such  cases,  accordingly,  the  alimentary  canal  is  large 
and  long;  and  is  divided  into  many  compartments,  in  which 
different  processes  of  disintegration,  transformation,  and  solution 
are  carried  on. 

In  the  common  fowl,  for  instance  (Fig.  16),  the  food,  which  con- 
sists mostly  of  grains,  and  frequently  of  insects  with  hard,  coria- 
ceous integument,  first  passes  down  the  oesophagus  (a)  into  a 
diverticulum  or  pouch  (6)  termed  the  crop.  Here  it  remains  for 
a  time,  mingled  with  a  watery  secretion  in  which  the  grains  are 
macerated  and  softened.  The  food  is  then  carried  farther  down 
until  it  reaches  a  second  dilatation  (c),  the  proventriculus,  or 
secreting   stomach.     The   mucous   membrane   here   is   thick   and 


DIGESTION. 


85 


glandular,  and  is  provided  witli  numerous  se-  Fig'  16. 

creting  follicles  or  crypts.  From  them  an 
acid  fluid  is  poured  out,  by  which  the  food  is 
subjected  to  further  changes.  It  next  passes 
into  the  gizzard  {d\  or  triturating  stomach,  a 
cavity  inclosed  by  thick,  muscular  walls,  and 
lined  with  a  remarkably  tough  and  horny 
epithelium.  Here  it  is  subjected  to  the  crush- 
ing and  grinding  action  of  the  muscular 
parietes,  assisted  by  grains  of  sand  and  gravel, 
which  the  animal  instinctively  swallows  with 
the  food,  by  which  it  is  so  triturated  and  dis- 
integrated, that  it  is  reduced  to  a  uniform  pulp, 
upon  which  the  digestive  fluids  can  effectually 
operate.  The  mass  then  passes  into  the  intes- 
tine (e),  where  it  meets  with  the  intestinal 
juices,  which  complete  the  process  of  solution; 
and  from  the  intestinal  cavity  it  is  finally  ab- 
sorbed in  a  liquid  form,  by  the  vessels  of  the 
mucous  membrane. 

In  the  ox,  again,  the  sheep,  the  camel,  the 
deer,  and  all  ruminating  animals,  there  are 
four  distinct  stomachs  through  which  the 
food  passes  in  succession;  each  lined  with 
mucous  membrane  of  a  different  structure, 
and  adapted  to  perform  a  different  part  in 
the  digestive  process  (Fig.  17).  When  first 
swallowed,  the  food  is  received  into  the  ru- 
men, or  paunch  (b),  a  large  sac,  itself  par- 
tially divided  by  incomplete  partitions,  and 
lined  by  a  mucous  membrane  thickly  set 
with  long  prominences  or  villi.  Here  it  ac- 
cumulates while  the  animal  is  feeding,  and  is 

retained  and  macerated  in  its  own  fluids.  When  the  anim.al  has 
finished  browsing,  and  the  process  of  rumination  commences,  the 
food  is  regurgitated  into  the  mouth  by  an  inverted  action  of -tfee 
muscular  walls  of  the  paunch  and  oesophagus,  and  slowly  masticated. 
It  then  descends  again  along  the  oesophagus ;  but  instead  of  enter- 
ing the  first  stomach,  as  before,  it  is  turned  off  by  a  muscular  valve 
into  the  second  stomach,  or  reticulum  (c),  which  is  distinguished 
by  the  intersecting  folds  of  its  mucous  membrane,  which  give  it 


Alimentary  Canal  of  Fowl. 
— a.  Oesophagus.  6.  Crop, 
c.  Proventriculus,  or  secret- 
ing stomach,  d.  Gizzard,  or 
triturating  stomach,  e.  In- 
testine. /.  Two  long  cjecal 
tubes  which  open  into  the  in- 
testine a  short  distance  above 
its  termination. 


86 


DIGESTION. 


CoMPOu>T)  Stomach  of  Ox. — a.  CEsopliagus. 
h.  Rumen,  or  first  stomach,  e.  Eeticulum,  or 
second,  d.  Omasus,  or  third,  e.  Obomasus, 
or  fourth.    /.  Duodenum. 


a  honey-combed  or  reticulated  appearance.    Here  the  food,  already 

tritura'ed    in    the    mouth,   and 
^^'  mixed  with  the  saliva,  is  further 

macerated  in  the  fluids  swallowed 
by  the  animal,  which  always  ac- 
cumulate in  considerable  quan- 
tity in  the  reticulum.  The  next 
cavity  is  the  omasus^  or  "psalte- 
rium"  (cf),  in  which  the  mucous 
membrane  is  arranged  in  longi- 
tudinal folds,  alternately  broad 
and  narrow,  lying  parallel  with 
each  other,  like  the  leaves  of  a 
book,  so  that  the  extent  of  mucous 
surface,  brought  in  contact  with 
the  food,  is  very  much  increased. 
The  exit  from  this  cavity  leads 
directly  into  the  obomasus^  or 
"  rennet"  (e),  which  is  the  true 
digestive  stomach,  in  which  the  mucous  membrane  is  softer,  thicker, 
and  more  glandular  than  elsewhere,  and  in  which  an  acid  and 
highly  solvent  fluid  is  secreted.  Then  follows  the  intestinal  canal 
with  its  various  divisions  and  variations. 

In  the  carnivora,  on  the  other  hand,  the  alimentary  canal  is 
shorter  and  narrower  than  in  the  preceding,  and  presents  fewer 
complexities.  The  food,  upon  which  these  animals  subsist,  is  softer 
than  that  of  the  herbivora,  and  less  encumbered  with  indigestible 
matter ;  so  that  the  process  of  its  solution  requires  a  less  extensive 
apparatus. 

In  the  human  species,  the  food  is  naturally  of  a  mixed  cha- 
racter, containing  both  animal  and  vegetable  substances.  But  the 
digestive  apparatus  in  man  resembles  almost  exactly  that  of  the 
carnivora.  For  the  vegetable  matters  which  we  take  as  food  are, 
in  the  first  place,  artificially  separated,  to  a  great  extent,  from  indi- 
gestible impurities ;  and  secondly,  they  are  so  softened  by  the 
process  of  cooking  as  to  become  nearly  or  quite  as  easily  digestible 
as  animal  substances. 

In  the  human  species,  however,  the  process  of  digestion,  though 
simpler  than  in  the  herbivora,  is  still  complicated.  The  alimentary 
canal  is  here,  also,  divided  into  different  compartments  or  cavities, 
which  communicate  with  each  other  by  narrow  orifices.    At  its 


DIGESTION. 


commencement  (Fig.  18),  we  find  the  cavity  of  the  mouth,  which  is 
guarded  at  its  posterior  extremity  by  the  muscular  valve  of  the 
isthmus  of  the  fauces. 
Through  the  pharynx  and 
oesophagus  (a),  it  com- 
municates with  the  second 
compartment,  or  the  sto- 
mach (5),  a  flask-shaped 
dilatation,  which  is  guarded 
at  the  cardiac  and  pyloric 
orifices  by  circular  bands 
of  muscular  fibres.  Then 
comes  the  small  intestine 
(e),  different  parts  of  which, 
owing  to  the  varying  struc- 
ture of  their  mucous  mem- 
branes, have  received  the 
different  names  of  duode- 
num, jejunum,  and  ileum. 
In  the  duodenum,  we  have 
the  orifices  of  the  biliary 
and  pancreatic  ducts  (/,  g). 
Finally,  we  have  the  large 
intestine  (/z,  i,  j\  k),  separated 
from  the  smaller  by  the 
ileo-C8ecal  valve,  and  ter- 
minating, at  its  lower  ex- 
tremity, by  the  anus,  at 
which  is  situated  a  double 
sphincter,  for  the  purpose 
of  guarding  its  orifice. 
Everywhere  the  alimentary 
canal  is  composed  of  a 
mucous  membrane  and  a 
muscular  coat,  with  a  layer 
of  submucous  areolar  tissue 
between  the  two.  The  mus- 
cular  coat   is   everywhere 

composed  of  a  double  layer  of  longitudinal  and  transverse  fibres, 
by  the  alternate  contraction  and  relaxation  of  which  the  food  is 
carried  through  the  canal  from  above  downward.     The  mucous 


Human  Alimentary  Canal. — a.  (Esophagus.  6.  Sto- 
mach, c.  Cardiac  orifice,  d.  Pylorus,  e.  Small  intestine. 
/.  Biliary  duct.  g.  Pancreatic  duct.  h.  Ascending  colon. 
i.  Transverse  colon.    J.  Descending  colon,     k.  Rectum. 


88  DIGESTION". 

membrane  presents,  also,  a  different  structure,  and  has  different 
properties  in  different  parts.  In  the  mouth  and  oesophagus,  it  is 
smooth,  with  a  hard,  whitish,  and  tessellated  epithelium.  This  kind 
of  epithelium  terminates  abruptly  at  the  cardiac  orifice  of  the 
stomach.  The  mucous  membrane  of  the  gastric  cavity  is  soft  and 
glandular,  covered  with  a  transparent,  columnar  epithelium,  and 
thrown  into  minute  folds  or  projections  on  its  free  surface,  which 
are  sometimes  reticulated  with  each  other.  In  the  small  intestine, 
we  find  large  transverse  folds  of  mucous  membrane,  the  valvulce 
conniventes,  the  minute  villosities  which  cover  its  surface,  and  the 
peculiar  glandular  structures  which  it  contains.  Finally,  in  the 
large  intestine,  the  mucous  membrane  is  again  different.  It  is  here 
smooth  and  shining,  free  from  villosities,  and  provided  with  a 
different  glandular  apparatus. 

Furthermore,  the  digestive  secretions,  also,  vary  in  these  different 
regions.  In  its  passage  from  above  downwards,  the  food  meets 
with  no  less  than  five  different  digestive  fluids.  First  it  meets  with 
the  saliva  in  the  cavity  of  the  mouth ;  second,  with  the  gastric  juice^ 
in  the  stomach;  third,  with  the  hile ;  fourth,  with  the  pancreatic 
fluid;  and  fifth,  with  the  intestinal  juice.  It  is  the  most  important 
characteristic  of  the  process  of  digestion,  as  established  by  modern 
researches,  that  different  elements  of  the  food  are  digested  in  different 
parts  of  the  alimentary  canal  by  the  agency  of  different  digestive  fluids. 
By  their  action,  the  various  ingredients  of  the  alimentary  mass  are 
successively  reduced  to  a  fluid  condition,  and  are  taken  up  by  the 
vessels  of  the  intestinal  mucous  membrane. 

The  action  which  is  exerted  upon  the  food  by  the  digestive 
fluids  is  not  that  of  a  simple  chemical  solution.  It  is  a  transforma- 
tion, by  which  the  ingredients  of  the  food  are  altered  in  character 
at  the  same  time  that  they  undergo  the  process  of  liquefaction. 
The  active  agent  in  producing  this  change  is  in  every  instance  an 
organic  matter,  which  enters  as  an  ingredient  into  the  digestive 
fluid;  and  which,  by  coming  in  contact  with  the  food,  exerts  upon 
it  a  catalytic  action,  and  transforms  its  ingredients  into  other  sub- 
stances. It  is  these  newly  formed  substances  which  are  finally 
absorbed  by  the  vessels,  and  mingled  with  the  general  current  of 
the  circulation. 

In  our  study  of  the  process  of  digestion,  the  different  digestive 
fluids  will  be  examined  separately,  and  their  action  on  the  aliment- 
ary substances  in  the  different  regions  of  the  digestive  apparatus 
successively  investigated. 


MASTICATION.  89 


MASTICATION. 


In  the  first  division  of  the  alimentary  canal,  viz.,  the  mouth,  the 
food  undergoes  simultaneously  two  different  operations,  viz.,  mas- 
tication and  insalivation.  Mastication  consists  in  the  cutting  and 
trituration  of  the  food  by  the  teeth,  by  the  action  of  which  it  is 
reduced  to  a  state  of  minute  subdivision.  This  process  is  entirely 
a  mechanical  one.  It  is  necessary,  in  order  to  prepare  the  food  for 
the  subsequent  action  of  the  digestive  fluids.  As  this  action  is 
chemical  in  its  nature,  it  will  be  exerted  more  promptly  and  effi- 
ciently if  the  food  be  finely  divided  than  if  it  be  brought  in  con- 
tact with  the  digestive  fluids  in  a  solid  mass.  This  is  always  the 
case  when  a  solid  body  is  subjected  to  the  chemical  action  of  a 
solvent  fluid ;  since,  by  being  broken  up  into  minute  particles,  it 
offers  a  larger  surface  to  the  contact  of  the  fluid,  and  is  more  readily 
attacked  and  dissolved  or  decomposed  by  it. 

In  the  structure  of  the  teeth,  and  their  physiological  action,  there 
are  certain  marked  differences,  corresponding  with  the  habits  of  the 
animal,  and  the  kind  of  food  upon  which  it  subsists.  In  fish  and 
serpents,  in  which  the  food  is  swallowed  entire,  and  in  which  the 
process  of  digestion,  accordingly,  is  comparatively  slow,  the  teeth 
are  simply  organs  of  prehension.  They  have  generally  the  form 
of  sharp,  curved  spines,  with  their  points  set  backward  (Fig.  19), 
and  arranged  in  a  double  or  triple  row 
about  the  edges  of  the  jaws,  and  sometimes  ^^?!^ 

covering  the  mucous  surfaces  of  the  mouth, 
tongue,  and  palate.  They  serve  merely  to 
retain  the  prey,  and  prevent  its  escape, 
after  it  has  been  seized  by  the  animal.     In 

.1  •  n  1  J.1  J?         Skull  op  Rattlesnake.     (After 

the  carnivorous  quadrupeds,  as  those  of    Achiiie-Eichard.) 
the  dog  and  cat  kind,  and  other  similar 

families,  there  are  three  different  kinds  of  teeth  adapted  to  different 
mechanical  purposes.  (Fig.  20.)  First,  the  incisors,  twelve  in  num- 
ber, situated  at  the  anterior  part  of  the  jaw,  six  in  the  superior, 
and  six  in  the  inferior  maxilla,  of  flattened  form,  and  placed  with 
their  thin  edges  running  from  side  to  side.  The  incisors,  as  their 
name  indicates,  are  adapted  for  dividing  the  food  by  a  cutting 
motion,  like  that  of  a  pair  of  shears.  Behind  them  come  the  canine 
teeth,  or  tusks,  one  on  each  side  of  the  upper  and  under  jaw. 
These  are  long,  curved,  conical,  and  pointed  ;  and  are  used  as 


90 


DIGESTION. 


weapons  of  offence,  and  for  laying  hold  of  and  retaining  tlie  prey. 
Lastly,  the  molars,  eight  or  more  in  number  on  each  side,  are 

larger  and  broader  than  the  incis- 
ors, and  provided  with  serrated 
edges,  each  presenting  several  sharp 
points,  arranged  generally  in  a  di- 
rection parallel  with  the  line  of  the 
jaw.  In  these  animals,  mastication 
is  very  imperfect,  since  the  food  is 
not  ground  up,  but  only  pierced 
and  mangled  by  the  action  of  the 
teeth  before  being  swallowed  into 
the  stomach.  In  the  herbivora,  on 
the  other  hand,  the  incisors  are  pre- 
sent only  in  the  lower  jaw  in  the  ruminating  animals,  though  in 
the  horse  they  are  found  in  both  the  upper  and  lower  maxilla  (Fig. 


Skull   of   Polar   Bear.     Anterior  view 
showing  incisors  and  canines. 


Fig.  21. 


Skull  of  the  Horse. 


Fig.  22. 


21).  They  are  used  merely  for  cutting  off  the  bundles  of  grass  or 
herbage,  on  which  the  animal  feeds.  The  canines  are  either  absent 
or  only  slightly  developed,  and  the  real  process  of 
mastication  is  performed  altogether  by  the  molars. 
These  are  large  and  thick  (Fig.  22),  and  present  a 
broad,  flat  surface,  diversified  by  variously  folded 
and  projecting  ridges  of  enamel,  with  shallow 
grooves,  intervening  between  them.  By  the  lateral 
rubbing  motion  of  the  roughened  surfaces  against 
each  other,  the  food  is  effectually  comminuted  and 
reduced  to  a  pulpy  mass. 

In  the  human  subject,  the  teeth  combine  the 


Molar  Tooth  of  the 
Horse.  Grinding  sur- 
face. 


MASTICATION. 


91 


In- 


human Teeth — Upper  Jaw. — a.  Incisors.    6.  Canines. 
Anterior  molars,     d.  Posterior  molars. 


characters  of  those  of  the  carnivora  and  the  herbivora.  (Fig.  23.) 
The  incisors  (a),  four  in 

number  in  each  jaw,  have,  ^ig-  23. 

as  in  other  instances,  a 
cuttingedge running  from 
side  to  side.  The  canines 
(&),  which  are  situated 
immediately  behind  the 
former,  are  much  less 
prominent  and  pointed 
than  in  the  carnivora,  and 
differ  less  in  form  from 
the  incisors  on  the  one 
hand,  and  the  first  molars 
on  the  other.  The  molars, 
again  (c,  d\  are  thick  and 
strong,  and  have  compa- 
ratively flat  surfaces,  like  those  of  the  herbivora ;  but  instead  of 
presenting  curvilinear  ridges,  are  covered  with  more  or  less  conical 
eminences,  like  those  of  the  carnivora.  In  the  human  subject, 
therefore,  the  teeth  are  evidently  adapted  for  a  mixed  diet,  consist- 
ing of  both  animal  and  vegetable  food.  Mastication  is  here  as 
perfect  as  it  is  in  the  herbivora,  though  less  prolonged  and  labori- 
ous ;  for  the  vegetable  substances  used  by  man,  as  already  remarked, 
are  previously  separated  to  a  great  extent  from  their  impurities, 
and  softened  by  cooking;  so  that  they  do  not  require,  for  their  mas- 
tication, so  extensive  and  powerful  a  triturating  apparatus.  Finally, 
animal  substances  are  more  completely  masticated  in  the  human 
subject  than  they  are  in  the  carnivora,  and  their  digestion  is  accord- 
ingly completed  with  greater  rapidity. 

We  can  easily  estimate,  from  the  facts  above  stated,  the  great 
importance,  to  the  digestive  process,  of  a  thorough  preliminary 
mastication.  If  the  food  be  hastily  swallowed  in  undivided  masses, 
it  must  remain  a  long  time  undissolved  in  the  stomach,  where  it 
will  become  a  source  of  irritation  and  disturbance ;  but  if  reduced 
beforehand,  by  mastication,  to  a  state  of  minute  subdivision,  it  is 
readily  attacked  by  the  digestive  fluids,  and  becomes  speedily  and 
completely  liquefied. 


92 


DIGESTION". 


SALIVA. 

At  the  same  time  that  the  food  is  masticated,  it  is  mixed  in  the 
cavity  of  the  mouth  with  the  first  of  the  digestive  fluids,  viz.,  the 
saliva.  Human  saliva,  as  it  is  obtained  directly  from  the  buccal 
cavity,  is  a  colorless,  slightly  viscid  and  alkaline  fluid,  with  a  spe- 
cific gravity  of  1005.  When  first  discharged,  it  is  frothy  and 
opaline,  holding  in  suspension  minute,  whitish  flocculi.  On  being 
allowed  to  stand  for  some  hours  in  a  cylindrical  glass  vessel,  an 
opaque,  whitish  deposit  collects  at  the  bottom,  while  the  supernatant 
fluid  becomes  clear.  The  deposit,  when  examined  by  the  micro- 
scope (Fig.  24),  is  seen  to 
consist  of  abundant  epithe- 
lium scales  from  the  internal 
surface  of  the  mouth,  de- 
tached by  mechanical  irrita- 
tion, minute,  roundish,  gra- 
nular, nucleated  cells,  appa- 
rently epithelium  from  the 
mucous  follicles,  a  certain 
amount  of  granular  matter, 
and  a  few  oil-globules.  The 
supernatant  fluid  has  a  faint 
bluish  tinge,  becomes  slightly 
opalescent  by  boiling,  and 
the  addition  of  nitric  acid. 
Alcohol  in  excess,  causes  the 
precipitation  of  abundant 
whitish  flocculi.  According  to  Bidder  and  Schmidt,^  the  composi- 
tion of  saliva  is  as  follows : — 


Buccal  asd  Glandulab  Epithelium,  with  Granular 
Matter  and  Oil-globules  ;  deposited  as  sediment  from 
human  saliva. 


CoMPOsiTiox  OF  Saliva. 

Water 

Organic  matter  ...... 

Sulpho-cyanide  of  potassium     .         .         .         . 
Phosphates  of  soda,  lime,  and  magnesia    . 
Chlorides  of  sodium  and  potassium  . 
Mixture  of  epithelium       .         .         .         •   .      . 


995.16 
1.34 

0.06 
.98 
.84 

1.62 


1000.00 
The  organic  substance  present  in  the  saliva  has  been  occasionally 


'  Verdaunngsssefte  und  Stoffwechsel.     Leipzig,  1852. 


SALIVA.  93 

known  by  the  name  of  piyaline.  It  is  coagulable  by  alcohol,  but 
not  by  a  boiling  temperature.  A  very  little  albumen  is  also  pre- 
sent, mingled  with  the  ptyaline,  and  produces  the  opalescence 
which  appears  in  the  saliva  when  raised  to  a  boiling  temperature. 
The  sulpho-cyanogen  may  be  detected  by  a  solution  of  chloride  of 
iron,  which  produces  the  characteristic  red  color  of  sulpho-cyanide 
of  iron.  The  alkaline  reaction  of  the  saliva  varies  in  intensity 
during  the  day,  but  is  nearly  always  sufficiently  distinct. 

The  saliva  is  not  a  simple  secretion,  but  a  mixture  of  four  dis- 
tinct fluids,  which  differ  from  each  other  in  the  source  from  which 
they  are  derived,  and  in  their  physical  and  chemical  properties. 
These  secretions  are,  in  the  human  subject,  first,  that  of  the  parotid 
gland ;  second,  that  of  the  submaxillary ;  third,  that  of  the  sub- 
lingual; and  fourth,  that  of  the  mucous  follicles  of  the  mouth. 
These  different  fluids  have  been  comparatively  studied,  in  the 
lower  animals,  by  Bernard,  Frerichs,  and  Bidder  and  Schmidt. 
The  parotid  saliva  is  obtained  in  a  state  of  purity  from  the  dog 
by  exposing  the  duct  of  Steno  where  it  crosses  the  masseter  muscle, 
and  introducing  into  it,  through  an  artificial  opening,  a  fine  silver 
canula.  The  parotid  saliva  then  runs  directly  from  its  external 
orifice,  without  being  mixed  with  that  of  the  other  salivary  glands. 
It  is  clear,  limpid,  and  watery,  without  the  slightest  viscidity,  and 
has  a  faintly  alkaline  reaction.  The  submaxillary  saliva  is  ob- 
tained in  a  similar  manner,  by  inserting  a  canula  into  Wharton's 
duct.  It  differs  from  the  parotid  secretion,  so  far  as  its  physical 
properties  are  concerned,  chiefly  in  possessing  a  well-marked  vis- 
cidity. It  is  alkaline  in  reaction.  The  sublingual  saliva  is  also 
alkaline,  colorless,  and  transparent,  and  possesses  a  greater  degree 
of  viscidity  than  that  from  the  submaxillary.  The  mucous  secre- 
tion of  the  follicles  of  the  mouth,  which  forms  properly  a  part  of 
the  saliva,  is  obtained  by  placing  a  ligature  simultaneously  on 
Wharton's  and  Steno's  ducts,  and  on  that  of  the  sublingual  gland, 
so  as  to  shut  out  from  the  mouth  all  the  glandular  salivary  secre- 
tions, and  then  collecting  the  fluid  secreted  by  the  buccal  mucous 
membrane.  This  fluid  is  very  scanty,  and  much  more  viscid  than 
either  of  the  other  secretions ;  so  much  so,  that  it  cannot  be  poured 
out  in  drops  when  received  in  a  glass  vessel,  but  adheres  strongly 
to  the  surface  of  the  glass. 

According  to  Bernard,^  the  principal  distinction  between  these 

'  Le(;ons  de  Physiologie  Experimentale,  Paris,  1856,  p.  93. 


^4  DIGESTION. 

different  salivary  fluids  resides  in  the  character  of  the  organic 
matter  peculiar  to  each  one.  The  organic  ingredient  of  the  parotid 
saliva  is  small  in  quantity,  perfectly  fluid,  and  analogous  in  some 
respects  to  albumen,  since  it  coagulates  by  a  boiling  temperature. 
That  of  the  submaxillary  is  moderately  viscid,  and  has  a  tendency 
to  solidify  or  gelatinize  on  cooling ;  while  that  of  the  sublingual 
and  mucous  secretions  is  excessively  viscid,  but  does  not  gelatinize 
at  a  low  temperature. 

Tlie  saliva  proper  consists,  therefore,  of  a  nearly  homogeneous 
mixture  of  all  these  different  secretions ;  of  which  that  from  the 
parotid  is  the  most  abundant,  tbat  of  the  sublingual  and  of  the 
mucous  follicles  of  the  mouth  the  least  so.  Bidder  and  Schmidt 
obtained,  from  one  of  the  parotid  glands  of  the  dog,  one  hundred 
and  thirty-six  grains  of  fluid  in  an  hour;  from  the  submaxillary, 
eighty-seven  grains ;  and  from  the  mucous  follicles  of  the  mouth, 
after  ligature  of  both  Wharton's  and  Steno's  ducts,  thirty-one 
grains.  The  saliva,  as  a  whole,  is  not  secreted  with  uniform 
rapidity  at  all  times.  While  fasting,  and  while  the  tongue  and 
jaws  are  at  rest,  it  is  supplied  in  but  small  quantity,  just  sufficient 
to  keep  the  mucous  membrane  of  the  mouth  moist  and  pliable. 
-  Any  movement  of  the  jaws,  however,  increases  the  rapidity  of  its 
flow.  It  is  still  more  powerfully  stimulated  by  the  introduction  of 
food,  particularly  that  which  has  a  decided  taste,  or  which  requires 
an  active  movement  of  the  jaws  for  its  mastication.  The  saliva  is 
then  poured  out  in  abundance,  and  continues  to  be  rapidly  secreted 
until  the  food  is  masticated  and  swallowed. 

A  very  curious  fact  has  been  observed  by  M.  Colin,  Professor  of 
Anatomy  and  Physiology  at  the  Veterinary  School  of  Alfort,'  viz., 
that  in  the  horse  and  ass,  as  well  as  in  the  cow  and  other  ruminat- 
ing animals,  the  parotid  glands  of  the  two  opposite  sides,  during 
mastication,  are  never  in  active  secretion  at  the  same  time;  but 
that  they  alternate  with  each  other,  one  remaining  quiescent  while 
the  other  is  active,  and  vice  versa.  In  these  animals,  mastication  is 
said  to  be  unilateral,  that  is,  when  the  animal  commences  feeding 
or  ruminating  the  food  is  triturated,  for  fifteen  minutes  or  more,  by 
the  molars  of  one  side  only.  It  is  then  changed  to  the  opposite 
side;  and  for  the  next  fifteen  minutes  mastication  is  performed  by 
the  molars  of  that  side  only.  It  is  then  changed  back  again,  and 
so  on  alternately,  so  that  the  direction  of  the  lateral  movements  of 

'  Traite  de  Physiologie  Comparee,  Paris,  1854,  p.  468. 


SALIVA.  95 

the  jaw  may  be  reversed  many  times  during  the  course  of  a  meal. 
By  establishing  a  salivary  fistula  simultaneously  on  each  side,  it  is 
found  that  the  flow  of  saliva  corresponds  with  the  direction  of  the 
masticatory  movement.  When  the  animal  masticates  on  the  right 
side,  it  is  the  right  parotid  which  secretes  actively,  while  but  little 
saliva  is  supplied  by  the  left ;  when  mastication  is  on  the  left  side, 
the  left  parotid  pours  out  an  abundance  of  fluid,  while  the  right  is 
nearly  inactive.  It  is  probable,  however,  that  this  alternation  of 
function  does  not  exist,  to  the  same  extent  at  least,  in  man  and  the 
carnivora,  in  whom  mastication  is  performed  very  nearly  on  both 
sides  at  once. 

Owing  to  the  variations  in  the  rapidity  of  its  secretion,  and  also 
to  the  fact  that  it  is  not  so  readily  excited  by  artificial  means  as 
by  the  presence  of  food,  it  becomes  somewhat  difiicult  to  estimate 
the  total  quantity  of  saliva  secreted  daily.  The  first  attempt  to  do 
so  was  made  by  Mitscherlich,'  who  collected  from  two  to  three  ounces 
in  twenty-four  hours  from  an  accidental  salivary  fistula  of  Steno's 
duct  in  the  human  subject ;  from  which  it  was  supposed  that  the 
total  amount  secreted  by  all  the  glands  was  from  ten  to  twelve  ounces 
daily.  As  this  man  was  a  hospital  patient,  however,  and  suffering 
from  constitutional  debility,  the  above  calculation  cannot  be  re-, 
garded  as  an  accurate  one,  and  accordingly  Bidder  and  Schmidt^ 
make  a  higher  estimate.  One  of  these  observers,  in  experimenting 
upon  himself,  collected  from  the  mouth  in  one  hour,  without  using 
any  artificial  stimulus  to  the  secretion,  1500  grains  of  saliva ;  and 
calculates,  therefore,  the  amount  secreted  daily,  making  an  allow- 
ance of  seven  hours  for  sleep,  as  not  far  from  25,000  grains,  or 
about  three  and  a  half  pounds  avoirdupois. 

On  repeating  this  experiment,  however,  we  have  not  been  able  to 
collect  from  the  mouth,  without  artificial  stimulus,  more  than  556 
grains  of  saliva  per  hour.  This  quantity,  however,  may  be  greatly 
increased  by  the  introduction  into  the  mouth  of  any  smooth  unirri- 
tating  substance,  as  glass  beads  or  the  like  ;  and  during  the  masti- 
cation of  food,  the  saliva  is  poured  out  in  very  much  greater  abund- 
ance. The  very  sight  and  odor  of  nutritious  food,  when  the  appetite 
is  excited,  will  stimulate  to  a  remarkable  degree  the  flow  of  saliva; 
and,  as  it  is  often  expressed,  "bring  the  water  into  the  mouth." 
Any  estimate,  therefore,  of  the  total  quantity  of  saliva,  based  on 
the  amount  secreted  in  the  intervals  of  mastication,  would  be  a  very 

«  Simon's  Chemistry  of  Man.     Phila.  ed.,  1846,  p.  295.  ^  Op.  cit.,  p.  14. 


96  DIGESTION. 

imperfect  one.  We  may  make  a  tolerably  accurate  calculation, 
however,  by  ascertaining  how  much,  is  really  secreted  during  a 
meal,  over  and  above  that  which  is  produced  at  other  times.  We 
have  found,  for  example,  by  experiments  performed  for  this  pur- 
pose, that  wheaten  bread  gains  during  complete  mastication  55  per 
cent,  of  its  weight  of  saliva ;  and  that  fresh  cooked  meat  gains, 
under  the  same  circumstances,  48  per  cent,  of  its  weight.  We  have 
already  seen  that  the  daily  allowance  of  these  two  substances,  for  a 
man  in  full  health,  is  19  ounces  of  bread,  and  16  ounces  of  meat. 
The  quantity  of  saliva,  then,  required  for  the  mastication  of  these 
two  substances,  is,  for  the  bread  4,572  grains,  and  for  the  meat  3,360 
grains.  If  we  now  calculate  the  quantity  secreted  between  meals 
as  continuing  for  22  hours  at  556  grains  per  hour,  we  have: — 

Saliva  required  for  mastication  of  bread  =    4572  grains. 
"  "  "  "  "    meat  =    3360      " 

"  secreted  in  intervals  of  meals  =  12232      " 


Total  quantity  in  twenty-four  hours  =  20164  grains  ; 

or  rather  less  than  3  pounds  avoirdupois. 

The  most  important  question,  connected  with  this  subject,  relates 
to  ihQ  function  of  the  saliva  in  the  digestive  process.  A  very  remarka- 
ble property  of  this  fluid  is  that  which  was  discovered  by  Leuchs 
in  Germany,  viz.,  that  it  possesses  the  power  of  converting  boiled 
starch  into  sugar,  if  mixed  with  it  in  equal  proportions,  and  kept 
for  a  short  time  at  the  temperature  of  100°  F.  This  phenomenon 
is  one  of  catalysis,  in  which  the  starch  is  transformed  into  sugar  by 
simple  contact  with  the  organic  substance  contained  in  the  saliva. 
This  organic  substance,  according  to  the  experiments  of  Mialhe,^ 
may  even  be  precipitated  by  alcohol,  and  kept  in  a  dry  state  for  an 
indefinite  length  of  time  without  losing  the  power  of  converting 
starch  into  sugar,  when  again  brought  in  contact  with  it  in  a  state 
of  solution. 

This  action  of  ordinary  human  saliva  on  boiled  starch  takes  place 
sometimes  with  great  rapidity.  Traces  of  glucose  may  occasionally 
be  detected  in  the  mixture  in  one  minute  after  the  two  substances 
have  been  brought  in  contact;  and  we  have  even  found  that  starch 
paste,  introduced  into  the  cavity  of  the  mouth,  if  already  at  the 
temperature  of  100°  F.,  will  yield  traces  of  sugar  at  the  end  of  half 
a  minute.     The  rapidity,  however,  with  which  this  action  is  mani- 

'  Chimie  appliquee  a  la  Physiologie  et  a  la  Therapeutique,  Paris,  1856,  p.  43. 


SALIVA.  97 

fested,  varies  very  mucli,  as  was  formerly  noticed  by  Lebraann,  at 
different  times ;  owing,  in  all  probability,  to  the  varying  constitution 
of  the  saliva  itself.  It  is  often  impossible,  for  example,  to  find  any 
evidences  of  sugar,  in  the  mixture  of  starch  and  saliva,  under  five, 
ten,  or  fifteen  minutes ;  and  it  is  frequently  a  longer  time  than  this 
before  the  whole  of  the  starch  is  completely  transformed.  Even 
when  the  conversion  of  the  starch  commences  very  promptly,  it  is 
often  a  long  time  before  it  is  finished.  If  a  thin  starch  paste,  for 
example,  which  contains  no  traces  of  sugar,  be  taken  into  the  mouth 
and  thoroughly  mixed  with  the  buccal  secretions,  it  will  often,  as 
already  mentioned,  begin  to  show  the  reaction  of  sugar  in  the  course 
of  half  a  minute ;  but  some  of  the  starchy  matter  still  remains,  and 
will  continue  to  manifest  its  characteristic  reaction  with  iodine,  for 
fifteen  or  twenty  minutes,  or  even  half  an  hour. 

The  above  action  of  the  saliva  on  starch,  according  to  the  experi- 
ments of  Magendie,  Bernard,  Bidder  and  Schmidt,  &c.,  does  not 
reside  in  either  the  parotid,  submaxillary  or  mucous  secretions 
taken  separately ;  but  only  in  the  mixed  saliva,  as  it  comes  from 
the  cavity  of  the  mouth.  The  submaxillary  and  mucous  secretions, 
however,  taken  together,  produce  the  change ;  though  neither  of  them 
has  any  effect  alone,  nor  even  when  mixed  artificially  with  the  saliva 
of  the  parotid. 

It  was  supposed,  when  this  property  of  converting  starch  into 
sugar  was  first  discovered  to  exist  in  the  saliva,  that  it  constituted 
the  true  physiological  action  of  the  secretion,  and  that  the  function 
of  the  saliva  was,  in  reality,  the  digestion  and  liquefaction  of  starchy 
substances.  It  was  very  soon  noticed,  however,  by  the  French 
observers,  that  this  property  of  the  saliva  was  rather  an  accidental 
than  an  essential  one ;  and  that,  although  starchy  substances  are 
really  converted  into  sugar,  if  mixed  with  saliva  in  a  test-tube,  yet 
they  are  not  affected  by  it  to  the  same  degree  in  the  natural  process 
of  digestion.  We  have  already  mentioned  above  the  extremely 
variable  activity  of  the  saliva,  in  this  respect,  at  different  times ; 
and  it  must  be  recollected,  also,  that  in  digestion  the  food  is  not 
retained  in  the  cavity  of  the  mouth,  but  passes  at  once,  after  mas- 
tication, into  the  stomach.  Several  German  observers,  as  Frerichs, 
Jacubowitsch,  Bidder,  and. Schmidt,  maintained  at  first  that  the 
saccharine  conversion  of  starch,  after  being  commenced  in  the 
mouth,  might  be,  and  actually  was,  completed  in  the  stomach.  We 
have  convinced  ourselves,  however,  by  frequent  experiments,  that 
this  is  not  the  case.  If  a  dog,  with  a  gastric  fistula,  be  fed  with  a 
7 


98  DIGESTIOISr. 

mixture  of  meat  and  boiled  starch,  and  portions  of  the  fluid  con- 
tents of  the  stomacli  withdrawn  afterward  through  the  fistula, 
the  starch  is  easily  recognizable  by  its  reaction  with  iodine  for  ten, 
fifteen,  and  twenty  minutes  afterward.  In  forty-five  minutes,  it  is 
diminished  in  quantity,  and  in  one  hour  has  usually  altogether  dis- 
appeared ;  but  no  sugar  is  to  be  detected  at  any  time.  Sometimes 
the  starch  disappears  more  rapidly  than  this ;  but  at  no  time,  accord- 
ing to  our  observations,  is  there  any  indication  of  the  presence  of 
sugar  in  the  gastric  fluids.  Bidder  and  Smith  have  also  concluded, 
from  subsequent  investigations,^  that  the  first  experiments  performed 
Tinder  their  direction  by  Jacubowitsch  were  erroneous;  and  it  is 
now  acknowledged  by  them,  as  well  as  by  the  Frenchi  observers, 
that  sugar  cannot  be  detected  in  the  stomach,  after  the  introduction 
of  starch,  in  any  form  or  by  any  method.  In  the  ordinary  process 
of  digestion,  in  fact,  starcby  matters  do  not  remain  long  enough  in 
the  mouth  to  be  altered  by  the  saliva,  but  pass  at  once  into  the  sto- 
mach. Here  they  meet  with,  the  gastric  fluids,  which  become  min- 
gled with  them,  and  prevent  the  change  which  would  otherwise  be 
effected  by  the  saliva.  We  have  found  that  the  gastric  juice  will 
interfere,  in  this  manner,  with  the  action  of  the  saliva  in  the  test- 
tube,  as  well  as  in  the  stomach.  If  two  mixtures  be  made,  one  of 
starch  and  saliva,  the  other  of  starch,  saliva,  and  gastric  juice,  and 
botb  kept  for  fifteen  minutes  at  the  temperature  of  100°  F.,  in  the 
first  mixture  the  starch  will  be  promptly  converted  into  sugar,  while 
in  the  second  no  such  change  will  take  place.  The  above  action, 
therefore,  of  saliva  on  starch,  though  a  curious  and  interesting  pro- 
perty, has  no  significance  as  to  its  physiological  function,  since  it 
does  not  take  place  in  the  natural  digestive  process.  We  shall  see 
hereafter  that  there  are  other  means  provided  for  the  digestion  of 
starchy  matters,  altogether  independent  of  the  action  of  the  saliva. 
The  true  function  of  the  saliva  is  altogether  a  physical  one.  Its 
action  is  simply  to  moisten  the  food  and  facilitate  its  mastication, 
as  well  as  to  lubricate  the  triturated  mass,  and  assist  its  passage 
down  the  oesophagus.  Food  which  is  hard  and  dry,  like  crusts, 
crackers,  &c,,  cannot  be  masticated  and  swallowed  with  readiness 
unless  moistened  by  some  fluid.  If  the  saliva,  therefore,  be  prevented 
from  entering  the  cavity  of  the  mouth,  its  loss  does  not  interfere 
directly  with  the  chemical  changes  of  the  food  in  digestion,  but  only 
with  its  mechanical  preparation.    This  is  the  result  of  direct  experi- 

"  Op.  cit.,  p.  26. 


SALIVA.  99 

ments  performed  by  various  observers.  Bidder  and  Schmidt/  after 
tying  Steno's  duct,  together  with  the  common  duct  of  the  sub- 
maxillary and  sublingual  glands  on  both  sides  in  the  dog,  found 
that  the  immediate  effect  of  such  an  operation  was  "a  remarkable 
diminution  of  the  fluids  which  exude  upon  the  surfaces  of  the  mouth; 
so  that  these  surfaces  retained  their  natural  moisture  only  so  long 
as  the  mouth  was  closed,  and  readily  became  dry  on  exposure  to 
contact  with  the  air.  Accordingly,  deglutition  became  evidently 
difficult  and  laborious,  not  only  for  dry  food,  like  bread,  but  even 
for  that  of  a  tolerably  moist  consistency,  like  fresh  meat.  The  ani- 
mals also  became  very  thirsty,  and  were  constantly  ready  to  drink," 

Bernard^  also  found  that  the  only  marked  effect  of  cutting  off" 
the  flow  of  saliva  from  the  mouth  was  a  difficulty  in  the  mechani- 
cal processes  of  mastication  and  deglutition.  He  first  administered 
to  a  horse  one  pound  of  oats,  in  order  to  ascertain  the  rapidity  with 
which  mastication  would  naturally  be  accomplished.  The  above 
quantity  of  grain  was  thoroughly  masticated  and  swallowed  at  the 
end  of  nine  minutes.  An  opening  had  been  previously  made 
in  the  oesophagus  at  the  lower  part  of  the  neck,  so  that  none  of  the 
food  reached  the  stomach;  but  each  mouthful,  as  it  passed  down  the 
oesophagus,  was  received  at  the  oesophageal  opening  and  examined 
by  the  experimenter.  The  parotid  duct  on  each  side  of  the  face 
was  then  divided,  and  another  pound  of  oats  given  to  the  animal. 
Mastication  and  deglutition  were  both  found  to  be  immediately 
retarded.  The  alimentary  masses  passed  down  the  oesophagus  at 
longer  intervals,  and  their  interior  was  no  longer  moist  and  pasty, 
as  before,  but  dry  and  brittle.  Finally,  at  the  end  of  twenty-five 
minutes,  the  animal  had  succeeded  in  masticating  and  swallowing 
only  about  three-quarters  of  the  quantity  which  he  had  previously 
disposed  of  in  nine  minutes. 

It  appears,  also,  from  the  experiments  of  Magendie,  Bernard,  and 
Lassaigne,  on  horses  and  cows,  that  the  quantity  of  saliva  absorbed 
by  the  food  during  mastication  is  in  direct  proportion  to  its  hard- 
ness and  dryness,  but  has  no  particular  relation  to  its  chemical 
qualities.  These  experiments  were  performed  as  follows :  The  oeso- 
phagus was  opened  at  the  lower  part  of  the  neck,  and  a  ligature 
placed  upon  it,  between  the  wound  and  the  stomach.  The  animal 
was  then  supplied  with  a  previously  weighed  quantity  of  food,  and 
this,  as  it  passed  out  by  the  oesophageal  opening,  was  received  into 

'  Op.  cit.,  p.  3. 

^  Lemons  de  Physiologie  Experimeutale,  Paris,  1856,  p.  146. 


100  DIGESTION. 

appropriate  vessels  and  again  weighed.  The  difference  in  weight, 
before  and  after  swallowing,  indicated  the  quantity  of  saliva  absorbed 
by  the  food.  The  following  table  gives  the  results  of  some  of  Las- 
saigne's  experiments,'  performed  upon  a  horse : — 

Kind  of  Food  employed.  Quantity  of  Saline  absokbed. 

For  100  parts  of  liay  there  were  absorbed  400  parts  saliva. 

"  barley  meal  "  186  " 

"  oats  "  113  " 

"  green  stalks  and  leaves  "  49  " 

It  is  evident,  from  the  above  facts,  that  the  quantity  of  saliva 
produced  has  not  so  much  to  do  with  the  chemical  character  of  the 
food  as  with  its  physical  condition.  When  the  food  is  dry  and 
hard,  and  requires  much  mastication,  the  saliva  is  secreted  in 
abundance ;  when  it  is  soft  and  moist,  a  smaller  quantity  of  the 
secretion  is  poured  out;  and  finally,  when  the  food  is  taken  in  a 
fluid  form,  as  soup  or  milk,  or  reduced  to  powder  and  moistened 
artificially  with  a  very  large  quantity  of  water,  it  is  not  mixed  at 
all  with  the  saliva,  but  passes  at  once  into  the  cavity  of  the  stomach. 
The  abundant  and  watery  fluid  of  the  parotid  gland  is  most  useful 
in  assisting  mastication;  while  the  glairy  and  mucous  secretion  of 
the  submaxillary  gland  and  the  muciparous  follicles  serve  to  lubri- 
cate the  exterior  of  the  triturated  mass,  and  facilitate  its  passage 
through  the  oesophagus. 

By  the  combined  operation  of  the  two  processes  which  the  food 
undergoes  in  the  cavity  of  the  mouth,  its  preliminary  preparation 
is  accomplished.  It  is  triturated  and  disintegrated  by  the  teeth, 
and,  at  the  same  time,  by  the  movements  of  the  jaws,  tongue,  and 
cheeks,  it  is  intimately  mixed  with  the  salivary  fluids,  until  the 
whole  is  reduced  to  a  soft,  pasty  mass,  of  the  same  consistency 
throughout.  It  is  then  carried  backward  by  the  semi-involuntary 
movements  of  the  tongue  into  the  pharynx,  and  conducted  by  the 
muscular  contractions  of  the  oesophagus  into  the  stomach. 

THE  GASTEIO  JUICE,  AND  STOMACH  DIGESTION. 

The  mucous  membrane  of  the  stomach  is  distinguished  by  its 
great  vascularity  and  the  abundant  glandular  apparatus  with  which 
it  is  provided.  Its  entire  thickness  is  occupied  by  certain  glandular 
organs,  the  gastric  tubules  or  follicles,  which  are  so  closely  set  as  to 
leave  almost  no  space  between  them  except  what  is  required  for  the 

'  Comptes  Rendus,  vol.  xxi.  p.  362. 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION.       101 


capillary  bloodvessels.  The  free  surface  of  the  gastric  mucous 
membrane  is  not  smooth,  but  is  raised  in  minute  ridges  and  pro- 
jecting eminences.  In  the  cardiac  portion  (Fig.  25),  these  ridges 
are  reticulated  with  each  other,  so  as  to  include  between  them 


Fig.  25. 


Fig.  26. 


Fig.  27. 


Fig.  25.  Free  surface  of  G.vstric  Macous  Me.mbrane,  viewed  from  above  ;  from  Pig's  Stomach,  Car- 
diac portion.     Magnified  70  diameters. 

Fig.  26.  Free  surface  of  Gastric  Mococts  Me.mbrane,  viewed  in  vertical  section;  from  Pig's 
Stomacli,  Pyloric  portion.     Magnified  420  diameters. 

polygonal  interspaces,  each  of  which  is  encircled  by  a  capillary 
network.  In  the  pyloric  portion  (Fig.  26),  these  eminences  are 
more  or  less  pointed  and  coni- 
cal in  form,  and  generally 
flattened  from  side  to  side. 
They  contain  each  a  capillary 
bloodvessel,  which  returns 
upon  itself  in  a  loop  at  the 
extremity  of  the  projection, 
and  communicates  freely  with 
adjacent  vessels.  The  gastric 
follicles  are  very  different  in 
different  parts  of  the  stomach. 
In  the  pyloric  portion  (Fig. 
27),  they  are  nearly  straight, 
simple  tubules,  ^\^  of  an  inch 
in  diameter,  easily  separated 
from  each  other,  lined  with 
glandular  epithelium,  and  ter- 
minating in  cul-de-sacs  at  the  under  surface  of  the  mucous  mem- 


Mncous  Membrane  of  Pig's  Stomach,  from  Pyloric 
portion;  vertical  section;  showing  gastric  tubules, 
and,  at  a,  a  closed  follicle.     Magnified  70  diameters. 


102 


DIGESTION. 


Gastric  Tdedles  from  Pig's  Stomach,  Pyloric  por- 
tion, showing  their  C^ecal  Extremities.  At  a,  a  cylin- 
drical cast  of  epithelium,  pressed  out  from  a  tubule, 
showing  the  size  of  its  cavity. 


brane.  They  are  sometimes  slightly  branched,  or  provided  with 
one  or  two  rounded  diverticula,  a  short  distance  above  their  ter- 
mination. They  open  on  the 
free  surface  of  the  mucous 
membrane,  in  the  interspaces 
between  the  projecting  folds 
or  villi.  Among  these  tubular 
glandules  there  is  also  found, 
in  the  gastric  mucous  mem- 
brane, another  kind  of  glandu- 
lar organ,  consisting  of  closed 
follicles,  similar  to  the  solitary 
glands  of  the  small  intestine. 
These  follicles,  which  are  not 
very  numerous,  are  seated  in 
the  lower  part  of  the  mucous 
membrane,  and  enveloped  by 
the  c£ecal  extremities  of  the 
tubules.  (Fig.  27,  a.) 

In  the  cardiac  portion  of 
the  stomach,  the  tubules  are  very  wide  in  the  superficial  part  of 
the  mucous  membrane,  and  lined  with  large,  distinctly  marked 

cylinder  epithelium  cells.  (Fig. 
29.)  In  the  deeper  parts  of 
the  membrane  they  become 
branched  and  considerably 
reduced  in  size.  From  the 
point  where  the  branching 
takes  place  to  where  they 
terminate  below  in  cul-de  sacs, 
they  are  lined  with  small 
glandular  epithelium  cells, 
and  closely  bound  together 
by  intervening  areolar  tissue, 
so  as  to  present  somewhat 
the  appearance  of  compound 
glandules. 

The     bloodvessels     which 
come  up  from  the  submucous 
layer  of  areolar  tissue  form  a 
close  plexus  around  all  these  glandules,  and  provide  the  mucous 


Gastric  Tubules  from  Pig's  Stomach  ;  Cardiac 
portion.  At  a,  a  large  tubule  dividing  into  two  small 
ones.  b.  Portion  of  a  tubule,  seen  endwise,  c.  Its 
central  cavity. 


THE    GASTEIC    JUICE,    AND    STOMACH    DIGESTION.        103 

membrane  with  an  abundant  supply  of  blood,  both  for  the  purposes 
of  secretion  and  absorption. 

That  part  of  digestion  which  takes  place  in  the  stomach  has 
always  been  regarded  as  nearly,  if  not  quite,  the  most  important 
part  of  the  whole  process.  The  first  observers  who  made  any 
approximation  to  a  correct  idea  of  gastric  digestion  were  Reaumur 
and  Spallanzani,  who  showed  by  various  methods  that  the  reduction 
and  liquefaction  of  the  food  in  the  stomach  could  not  be  owing  to  a 
mere  contact  with  the  gastric  mucous  membrane,  or  to  compression 
by  the  muscular  walls  of  the  organ ;  but  that  it  must  be  attributed 
to  a  digestive  fluid  secreted  by  the  mucous  membrane,  which  pene- 
trates the  food  and  reduces  it  to  a  fluid  form.  They  regarded  this 
process  as  a  simple  chemical  solution,  and  considered  the  gastric 
juice  as  a  universal  solvent  for  all  alimentary  substances.  They 
succeeded  even  in  obtaining  some  of  this  gastric  juice,  mingled 
probably  with  many  impurities,  by  causing  the  animals  upon  which 
they  experimented  to  swallow  sponges  attached  to  the  ends  of 
cords,  by  which  they  were  afterwards  withdrawn,  and  the  fluids, 
which  they  had  absorbed,  expressed  and  examined. 

The  first  decisive  experiments  on  this  point,  however,  were  those 
performed  by  Dr.  Beaumont,  of  the  U.  S.  Army,  on  the  person  of 
Alexis  St.  Martin,  a  Canadian  boatman,  who  had  a  permanent  gas- 
tric fistula,  accidentally  produced  by  a  gunshot  wound.  The  musket, 
which  was  loaded  with  buckshot  at  the  time  of  the  accident,  was 
discharged  at  the  distance  of  a  few  feet  from  St.  Martin's  body,  in 
such  a  manner  as  to  tear  away  the  integument  at  the  lower  part  of 
the  left  chest,  open  the  pleural  cavity,  and  penetrate,  through  the 
lateral  portion  of  the  diaphragm,  into  the  great  pouch  of  the  stomach. 
After  the  integument  and  the  pleural  and  peritoneal  surfaces  had 
united  and  cicatrized,  there  remained  a  permanent  opening,  of  about 
four-fifths  of  an  inch  in  diameter,  leading  into  the  left  extremity  of 
the  stomach,  which  was  usually  closed  by  a  circular  valve  of  pro- 
truding mucous  membrane.  This  valve  could  be  readily  depressed 
at  any  time,  so  as  to  open  the  fistula  and  allow  the  contents  of  the 
stomach  to  be  extracted  for  examination. 

Dr.  Beaumont  experimented  upon  this  person  at  various  intervals 
from  the  year  1825  to  1832.^  He  established  during  the  course  of 
his  examinations  the  following  important  facts :  First,  that  the  ac. 
tive  agent  in  digestion  is  an  acid  fluid,  secreted  by  the  walls  of  the 

'  Experiments  and  Observations  on  tlie  Gastric  Juice.     Boston,  1834. 


10^  DIGESTION", 

stomach  ;  secondly,  that  this  fluid  is  poured  out  by  the  glandular 
walls  of  the  organ  only  during  digestion,  and  under  the  stimulus  of 
the  food ;  and  finally,  that  it  will  exert  its  solvent  action  upon  the 
food  outside  the  body  as  well  as  in  the  stomach,  if  kept  in  glass 
phials  upon  a  sand  bath,  at  the  temperature  of  100°  F.  He  made 
also  a  variety  of  other  interesting  investigations  as  to  the  effect 
of  various  kinds  of  stimulus  on  the  secretion  of  the  stomach,  the 
rapidity  with  which  the  process  of  digestion  takes  place,  the  com- 
parative digestibility  of  various  kinds  of  food,  &c.  &c. 

Since  Dr.  Beaumont's  time  it  has  been  ascertained  that  similar 
gastric  fistulee  may  be  produced  at  will  on  some  of  the  lower  animals 
by  a  simple  operation ;  and  the  gastric  juice  has  in  this  way  been 
obtained,  usually  from  the  dog,  by  Blondlot,  Schwann,  Bernard, 
Lehmann  and  others.  The  simplest  and  most  expeditious  mode 
of  doing  the  operation  is  the  best.  An  incision  should  be  made 
through  the  abdominal  parietes  in  the  median  line,  over  the  great 
curvature  of  the  stomach.  The  anterior  wall  of  the  organ  is  then 
to  be  seized  with  a  pair  of  hooked  forceps,  drawn  out  at  the  external 
wound,  and  opened  with  the  point  of  a  bistoury.  A  short  silver 
canula  one-half  to  three-quarters  of  an  inch  in  diameter,  armed  at 
each  extremity  with  a  narrow  projecting  rim  or  flange,  is  then  in- 
serted into  the  wound  in  the  stomach,  the  edges  of  which  are  fast- 
ened round  the  tube  with  a  ligature  in  order  to  prevent  the  escape 
of  the  gastric  fluids  into  the  peritoneal  cavity.  The  stomach  is  then 
returned  to  its  place  in  the  abdomen,  and  the  canula  allowed  to  re- 
main with  its  external  flange  resting  upon  the  edges  of  the  wound 
in  the  abdominal  integuments,  which  are  to  be  drawn  together  by 
sutures.  The  animal  may  be  kept  perfectly  quiet,  during  the  ope- 
ration, by  the  administration  of  ether  or  chloroform.  In  a  few 
days  the  ligatures  come  awa}^,  the  wounded  peritoneal  surfaces  are 
united  with  each  other,  and  the  canula  is  retained  in  a  permanent 
gastric  fistula ;  being  prevented  by  its  flaring  extremities  both  from 
falling  out  of  the  abdomen  and  from  being  accidentally  pushed  into 
the  stomach.  It  is  closed  externally  by  a  cork,  which  may  be  with- 
drawn at  pleasure,  and  the  contents  of  the  stomach  withdrawn  for 
examination. 

Experiments  conducted  in  this  manner  confirm,  in  the  main,  the 
results  obtained  by  Dr.  Beaumont.  Observations  of  this  kind  are 
in  ^ome  respects,  indeed,  more  satisfactory  when  made  upon  the 
lower  animals,  than  upon  the  human  subject;  since  animals  are  en- 
tirely under  the  control  of  the  experimenter,  and  all  sources  of 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION".       105 

deception  or  mistake  are  avoided,  while  the  investigation  is,  at  the 
same  time,  greatly  facilitated  by  the  simple  character  of  their  food. 
The  gastric  juice,  like  the  saliva,  is  secreted  in  considerable 
quantity  only  under  the  stimulus  of  recently  ingested  food.  Dr. 
Beaumont  states  that  it  is  entirely  absent  during  the  intervals  of 
digestion ;  and  that  the  stomach  at  that  time  contains  no  acid  fluid, 
but  only  a  little  neutral  or  alkaline  mucus.  He  was  able  to  obtain 
a  sufficient  quantity  of  gastric  juice  for  examination,  by  gently  irri- 
tating the  mucous  membrane  with  a  gum-elastic  catheter,  or  the  end 
of  a  glass  rod,  and  by  collecting  the  secretion  as  it  ran  in  drops 
from  the  fistula.  On  the  introduction  of  food,  he  found  that  the 
mucous  membrane  became  turgid  and  reddened,  a  clear  acid  fluid 
collected  everywhere  in  drops  underneath  the  layer  of  mucus  lin- 
ing the  walls  of  the  stomach,  and  was  soon  poured  out  abundantly 
into  its  cavity.  We  have  found,  however,  that  the  rule  laid  down 
by  Dr.  Beaumont  in  this  respect,  though  correct  in  the  main,  is  not 
invariable.  The  truth  is,  the  irritability  of  the  gastric  mucous 
membrane,  and  the  readiness  with  which  the  flow  of  gastric  juice 
may  be  excited,  varies  considerably  in  different  animals ;  even  in 
those  belonging  to  the  same  species.  In  experimenting  with  gastric 
fistulae  on  different  dogs,  for  example,  we  have  found  in  one  instance, 
like  Dr.  Beaumont,  that  the  gastric  juice  was  always  entirely  absent 
in  the  intervals  of  digestion ;  the  mucous  membrane  then  present- 
ing invariably  either  a  neutral  or  slightly  alkaline  reaction.  In 
this  animal,  which  was  a  perfectly  healthy  one,  the  secretion  could 
not  be  excited  by  any  artificial  means,  such  as  glass  rods,  metallic 
catheters,  and  the  like ;  but  only  by  the  natural  stimulus  of  ingested 
food.  We  have  even  seen  tough  and  indigestible  pieces  of  tendon, 
introduced  through  the  fistula,  expelled  again  in  a  few  minutes,  one 
after  the  other,  without  exciting  the  flow  of  a  single  drop  of  acid 
fluid;  while  pieces  of  fresh  meat,  introduced  in  the  same  way,  pro- 
duced at  once  an  abundant  supply.  In  other  instances,  on  the  con- 
trary, the  introduction  of  metallic  catheters,  &c.j  into  the  empty 
stomach  has  produced  a  scanty  flow  of  gastric  juice ;  and  in  experi- 
menting upon  dogs  that  have  been  kept  without  food  during  various 
periods  of  time  and  then  killed  by  section  of  the  medulla  oblongata, 
we  have  usually,  though  not  always,  found  the  gastric  mucous  mem- 
brane to  present  a  distinctly  acid  reaction,  even  after  an  abstinence 
of  six,  seven,  and  eight  days.  There  is  at  no  time,  however,  under 
these  circumstances,  any  considerable  amount  of  fluid  present  in 


106  DIGESTION. 

the  stomacli ;  but  onl}^  just  sufficient  to  moisten  the  gastric  mucous 
membrane,  and  give  it  an  acid  reaction. 

The  gastric  juice,  which  is  obtained  by  irritating  the  stomach 
with  a  metallic  catheter,  is  clear,  perfectly  colorless,  and  acid  in 
reaction.  A  sufficient  quantity  of  it  cannot  be  obtained  by  this 
method  for  any  extended  experiments ;  and  for  that  purpose,  the 
animal  should  be  fed,  after  a  fast  of  twenty-four  hours,  with  fresh 
lean  meat,  a  little  hardened  by  short  boiling,  in  order  to  coagulate 
the  fluids  of  the  muscular  tissue,  and  prevent  their  mixing  with  the 
gastric  secretion.  No  effect  is  usually  apparent  within  the  first  five 
minutes  after  the  introduction  of  the  food.  At  the  end  of  that  time 
the  gastric  juice  begins  to  flow ;  at  first  slowly,  and  in  drops.  It  is 
then  perfectly  colorless,  but  very  soon  acquires  a  slight  amber 
tinge.  It  then  begins  to  flow  more  freely,  usually  in  drops,  but 
often  running  for  a  few  seconds  in  a  continuous  stream.  In  this 
way  from  lij  to  ^iiss  may  be  collected  in  the  course  of  fifteen 
minutes.  After  this  it  becomes  somewhat  turbid  with  the  debris 
of  the  food,  which  has  begun  to  be  disintegrated ;  but  from  this  it 
may  be  readily  separated  by  filtration.  After  three  hours,  it  con- 
tinues to  run  freely,  but  has  become  very  much  thickened,  and 
even  grumous  in '  consistency,  from  the  abundant  admixture  of 
alimentary  debris.  In  six  hours  after  the  commencement  of  diges- 
tion it  runs  less  freely,  and  in  eight  hours  has  become  very  scanty, 
though  it  continues  to  preserve  the  same  physical  appearances  as 
before.  It  ceases  to  flow  altogether  in  from  nine  to  twelve  hours, 
according  to  the  quantity  of  food  taken. 

For  purposes  of  examination,  the  fluid  drawn  during  the  first 
fifteen  minutes  after  feeding  should  be  collected,  and  separated  by 
filtration  from  accidental  impurities.  Obtained  in  this  way,  the 
gastric  juice  is  a  clear,  watery  fluid,  without  any  appreciable  vis- 
cidity, very  distinctly  acid  to  test  paper,  of  a  faint  amber  color, 
and  with  a  specific  gravity  of  1010.  It  becomes  opalescent  on 
boiling,  owing  to  the  coagulation  of  its  organic  ingredients.  The 
following  is  the  composition  of  the  gastric  juice  of  the  dog,  based 
on  a  comparison  of  various  analyses  by  Lehmann,  and  Bidder  and 
Schmidt: — 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTIOISr.        107 

Composition  of  Gastric  Juice. 

Water 975.00 

Organic  matter           ........  15.00 

Lactic  acid        .........  4.78 

Chloride  of  sodium  .         .         .         .         .         .         .         .  1.70 

"         "   potassium       .         .         .         .         •         .         •  1.08 

"         "    calcium 0.20 

"          "    ammoniura     .......  0.65 

Phosphate  of  lime     ........  1.48 

"           "   magnesia 0.06 

"           "   iron 0.05 

1000.00 

In  place  of  lactic  acid,  Bidder  and  Sclimidt  found,  in  most  of  their 
analyses,  hydrochloric  acid.  Lehmann  admits  that  a  small  quantity 
of  hydrochloric  acid  is  sometimes  present,  but  regards  lactic  acid  as 
much  the  most  abundant  and  important  of  the  two.  Robin  and 
Verdeil  also  regard  the  acid  reaction  of  the  gastric  juice  as  due  to 
lactic  acid ;  and,  finally,  Bernard  has  shown,^  by  a  series  of  well 
contrived  experiments,  that  the  free  acid  of  the  dog's  gastric  juice 
is  undoubtedly  the  lactic ;  and  that  the  hydrochloric  acid  obtained 
by  distillation,  is  really  produced  by  a  decomposition  of  the 
chlorides,  which  enter  into  the  composition  of  the  fresh  juice. 

The  free  acid  is  an  extremely  important  ingredient  of  the  gastric 
secretion,  and  is,  in  fact,  essential  to  its  physiological  properties; 
for  the  gastric  juice  will  not  exert  its  solvent  action  upon  the  food, 
after  it  has  been  neutralized  by  the  addition  of  an  alkali  or  an 
alkaline  carbonate. 

The  most  important  ingredient  of  the  gastric  juice,  beside  the 
free  acid,  is  its  organic  matter  or  "  ferment,"  which  is  sometimes 
known  under  the  name  of  -pepsine.  This  name,  "pepsine,"  was 
originally  given  by  Schwann  to  a  substance  which  he  obtained 
from  the  mucous  membrane  of  the  pig's  stomach,  by  macerating  it 
in  distilled  water  until  a  putrid  odor  began  to  be  developed.  The 
substance  in  question  was  precipitated  from  the  watery  infusion 
by  the  addition  of  alcohol,  and  dried ;  and  if  dissolved  afterward 
in  acidulated  water,  it  was  found  to  exert  a  solvent  action  on  boiled 
white  of  Qgg.  This  substance,  however,  did  not  represent  precisely 
the  natural  ingredient  of  the  gastric  secretion,  and  was  probably  a 
mixture  of  various  matters,  some  of  them  the  products  of  com- 
mencing decomposition  of  the  mucous  membrane  itself.  The  name 
pepsine,  if  it  be  used  at  all,  should  be  applied  to  the  organic  matter 

'  Le9ons  de  Physiologie  Experimentale,  Paris,  1856,  p.  396. 


108 


DIGESTION. 


wTaicTi  naturally  occurs  in  solution  in  the  gastric  juice.  It  is  alto- 
gether unessential,  in  this  respect,  from  what  source  it  may  be 
originally  derived.  It  has  been  regarded  by  Bernard  and  others, 
o'n  somewhat  insufficient  grounds,  as  a  product  of  the  alteration  of 
the  mucus  of  the  stomach.  But  whatever  be  its  source,  since  it  is 
always  present  in  the  secretion  of  the  stomach,  and  takes  an  active 
part  in  the  performance  of  its  function,  it  can  be  regarded  in  ifo 
other  light  than  as  a  real  anatomical  ingredient  of  the  gastric  juice, 
and  as  essential  to  its  constitution. 

Pepsine  is  precipitated  from  its  solution  in  the  gastric  juice  by 
absolute  alcohol,  and  by  various  metallic  salts,  but  is  not  affected 
by  ferrocyanide  of  potassium.  It  is  precipitated  also,  and  coagu- 
lated by  a  boiling  temperature;  and  the  gastric  juice,  accordingly, 
after  being  boiled,  becomes  turbid,  and  loses  altogether  its  power 
of  dissolving  alimentary  substances.  Gastric  juice  is  also  affected 
in  a  remarkable  manner  by  being  mingled  with  Ule.  We  have 
found  that  four  to  six  drops  of  dog's  bile  precipitate  completely 
with  5j  of  gastric  juice  from  the  same  animal;  so  that  the  whole  of 
the  biliary  coloring  matter  is  thrown  down  as  a  deposit,  and  the 
filtered  fluid  is  found  to  have  lost  entirely  its  digestive  power, 
though  it  retains  an  acid  reaction. 

.A  very  singular  property  of  the  gastric  juice  is  its  inaptitude  for 
putrefaction.  It  may  be  kept  for  an  indefinite  length  of  time  in  a 
common  glass- stoppered  bottle  without  developing  any  putrescent 
odor.  A  light  deposit  generally  c^ollects  at  the  bottom,  and  a  con- 
fervoid  vegetable  growth  or  "mould"  often  shows  itself  in  the  fluid 

after  it  has  been  kept  for  one 
or  two  weeks.  This  growth 
has  the  form  of  white,  globular 
masses,  each  of  which  is  com- 
posed of  delicate  radiating 
branched  filaments  (Fig.  30)  ; 
each  filament  consisting  of 
a  row  of  elongated  cells,  like 
other  vegetable  growths  of  a 
similar  nature.  These  growths, 
however,  are  not  accompa- 
nied by  any  putrefactive 
changes,  and  the  gastric  juice 
retains  its  acid  reaction  and 

CONFERVOID  Vegetable,  growing  iu  the  Gastric  Juice      itS     digCStivC      prOpCrticS     for 
of  the  Dog.     The  fibres  have  an  average  diameter  of      fi^nT-i-y-  months 
] -7000th  of  an  inch.  -^ 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION.       109 

By  experimenting  artificially  with  gastric  juice  on  various  ali- 
mentary substances,  such  as  meat,  boiled  white  of  egg,  &c.,  it  is 
found,  as  Dr.  Beaumont  formerly  observed,  to  exert  a  solvent  action 
on  these  substances  outside  the  body,  as  well  as  in  the  cavity  of 
the  stomach.  This  action  is  most  energetic  at  the  temperature  of 
100°  F.  It  gradually  diminishes  in  intensity  below  that  point,  and 
ceases  altogether  near  32°.  If  the  temperature  be  elevated  above 
100°  the  action  also  becomes  enfeebled,  and  is  entirely  suspended 
about  160°,  or  the  temperature  of  coagulating  albumen.  Contrary 
to  what  was  supposed,  however,  by  Br.  Beaumont  and  his  predeces- 
sors, the  gastric  juice  is  not  a  universal  solvent  for  all  alimentary 
substances,  but  on  the  contrary,  affects  only  a  single  class  of  the 
proximate  principles,  viz.,  the  albuminoid  or  organic  substances. 
Neither  starch  nor  oil,  when  digested  in  it  at  the  temperature  of 
the  body,  suffers  the  slightest  chemical  alteration.  Fatty  matters 
are  simply  melted  by  the  heat,  and  starchy  substances  are  only 
hydrated  and  gelatinized  to  a  certain  extent  by  the  combined 
influence  of  the  warmth  and  moisture.  Solid  and  semi-solid 
albuminoid  matters,  however,  are  at  once  attacked  and  liquefied 
by  the  digestive  fluid.  Pieces  of  coagulated  white  of  egg  sus- 
pended in  it,  in  a  test-tube,  become  gradually  softened  on  their 
exterior,  and  their  edges  become  pale  and  rounded.  They  grow  thin 
and  transparent ;  and  their  substance  finally  melts  away,  leaving  a 
light,  scanty  deposit,  which  collects  at  the  bottom  of  the  test-tube. 
While  the  disintegrating  process  is  going  on,  it  may  be  almost 
always  noticed  that  minute,  opaque  spots  show  themselves  in  the 
substance  of  the  liquefying  albumen,  indicating  that  certain  parts 
of  it  are  less  easily  attacked  than  the  rest ;  and  the  deposit  which 
remains  at  the  bottom  is  probably  also  composed  of  some  ingre- 
dient, not  soluble  in  the  gastric  juice.  If  pieces  of  fresh  meat  be 
treated  in  the  same  manner,  the  areolar  tissue  entering  into  its  com- 
position is  first  dissolved,  so  that  the  muscular  bundles  become  more 
distinct,  and  separate  from  each  other.  They  gradually  fall  apart, 
and  a  little  brownish  deposit  is  at  last  all  that  remains  at  the  bottom 
of  the  tube.  If  the  hard,  adipose  tissue  of  beef  or  mutton  be  sub- 
jected to  the  same  process,  the  walls  of  the  fat  vesicles  and  the 
intervening  areolar  tissue,  together  with  the  capillary  bloodvessels, 
&;c.,  are  dissolved ;  while  the  oily  matters  are  set  free  from  their 
envelops,  and  collect  in  a  white,  opaque  layer  on  the  surface.  In 
cheese,  the  casein  is  dissolved,  and  the  oil  set  free,  as  above.  In 
bread,  the  gluten  is  digested,  and  the  starch  left  unchanged.     In 


110  DIGESTIOISr. 

milk,  the  casein  is  first  coagulated  by  contact  with  the  acid  gastric 
fluids,  and  afterward  slowly  liquefied,  like  other  albuminoid  sub- 
stances. 

The  time  required  for  the  complete  liquefaction  of  these  sub- 
stances varies  with  the  quantity  of  matter  present,  and  with  its  state 
of  cohesion.  The  process  is  hastened  by  occasionally  shaking  up 
the  mixture,  so  as  to  separate  the  parts  already  disintegrated,  and 
bring  the  gastric  fluid  into  contact  with  fresh  portions  of  the 
digestible  substance. 

The  liquefying  process  which  the  food  undergoes  in  the  gastric 
juice  is  not  a  sknple  solution.  It  is  a  catalytic  transformation, 
produced  in  the  albuminoid  substances  by  contact  with  the  or- 
ganic matter  of  the  digestive  fluid.  This  organic  matter  acts  in 
a  similar  manner  to  that  of  the  catalytic  bodies,  or  "ferments," 
generally.  Its  peculiarity  is  that,  for  its  active  operation,  it  re- 
quires to  be  dissolved  in  an  acidulated  fluid.  In  common  with 
other  ferments,  it  requires  also  a  moderate  degree  of  warmth ;  its 
action  being  checked,  both  by  a  very  low,  and  a  very  high  tempe- 
rature. By  its  operation  the  albuminoid  matters  of  the  food,  what- 
ever may  have  been  their  original  character,  are  all,  without  dis- 
tinction, converted  into  a  new  substance,  viz.,  albuminose.  This 
substance  has  the  general  characters  belonging  to  the  class  of 
organic  matters.  It  is  uncrystallizable,  and  contains  nitrogen  as 
an  ultimate  element.  It  is  precipitated,  like  albumen,  by  an  excess 
of  alcohol,  and  by  the  metallic  salts ;  but  unlike  albumen,  is  not 
affected  by  nitric  acid  or  a  boiling  temperature.  It  is  freely  soluble 
in  water,  and  after  it  is  once  produced  by  the  digestive  process, 
remains  in  a  fluid  condition,  and  is  ready  to  be  absorbed  by  the 
vessels.  In  this  way,  casein,  fibrin,  musculine,  gluten,  &c.,  are  all 
reduced  to  the  condition  of  albuminose.  By  experimenting  as 
above,  with  a  mixture  of  food  and  gastric  juice  in  test  tubes,  we 
have  found  that  the  casein  of  cheese  is  entirely  converted  into 
^albuminose,  and  dissolved  under  that  form.  A  very  considerable 
portion  of  raw  white  of  egg,  however,  dissolves  in  the  gastric  juice 
directly  as  albumen,  and  retains  its  property  of  coagulating  by 
heat.  Soft-boiled  white  of  egg  and  raw  meat  are  principally  con- 
verted into  albuminose;  but  at  the  same  time,  a  small  portion  of 
albumen  is  also  taken  up  unchanged. 

The  above  process  is  a  true  liquefaction  of  the  albuminoid  sub- 
stances, and  not  a  simple  disintegration.  If  fresh  meat  be  cut  into 
small  pieces,  and  artificially  digested  in  gastric  juice  in  test  tubes. 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION.        Ill 

at  100°  F.,  and  the  process  assisted  by  occasional  gentle  agitation, 
the  fluid  continues  to  take  up  more  and  more  of  the  digestible 
material  for  from  eight  to  ten  hours.  At  the  end  of  that  time  if  it 
be  separated  and  filtered,  the  filtered  fluid  has  a  distinct,  brownish 
color,  and  is  saturated  with  dissolved  animal  matter.  Its  specific 
gravity  is  found  to  have  increased  from  1010  to  1020 ;  and  on  the 
addition  of  alcohol  it  becomes  turbid,  with  a  very  abundant  whitish 
precipitate  (albuminose).  There  is  also  a  peculiar  odor  developed 
during  this  process,  which  resembles  that  produced  in  the  malting 
of  barley. 

Albuminose,  in  solution  in  gastric  juice,  has  several  peculiar 
properties.  One  of  the  most  remarkable  of  these  is  that  it  inter- 
feres with  the  operation  of  Trommer's  test  for  grape  sugar  (see 
page  52).  We  first  observed  and  described  this  peculiarity  in 
1854,'  but  could  not  determine,  at  that  time,  upon  what  particular 
ingredient  of  the  gastric  juice  it  depended.  A  short  time  subse- 
quently it  was  also  noticed  by  M.  Longet,  in  Paris,  who  published 
his  observations  in  the  Gazette  Sebdomadaire  for  February  9th, 
1855.^  He  attributed  the  reaction  not  to  the  gastric  juice  itself, 
but  to  the  albuminose  held  in  solution  by  it.  We  have  since  found 
this  explanation  to  be  correct.  Gastric  juice  obtained  from  the 
empty  stomach  of  the  fasting  animal,  by  irritation  with  a  metallic 
catheter,  which  is  clear  and  perfectly  colorless,  does  not  interfere 
in  any  way  with  Trommer's  test ;  but  if  it  be  macerated  for  some 
hours  in  a  test-tube  with  finely  chopped  meat,  at  a  temperature  of 
100°,  it  will  then  be  found  to  have  acquired  the  property  in  a 
marked  degree.  The  reaction  therefore  depends  undoubtedly  upon 
the  presence  of  albuminose  in  solution.  As  the  gastric  juice,  drawn 
from  the  dog's  stomach  half  an  hour  or  more  after  the  introduction 
of  food,  already  contains  some  albuminose  in  solution,  it  presents 
the  same  reaction.  If  such  gastric  juice  be  mixed  with  a  small 
quantity  of  glucose,  and  Trommer's  test  applied,  no  peculiarity  is 
observed  on  first  dropping  in  the  sulphate  of  copper ;  but  on  adding 
afterward  the  solution  of  potass,  the  mixture  takes  a  rich  purple  hue, 
instead  of  the  clear  blue  tinge,  which  is  presented  under  ordinary 
circumstances.  On  boiling,  the  color  changes  to  claret,  cherry  red, 
and  finally  to  a  light  yellow;  but  no  oxide  of  copper  is  deposited,  and 
the  fluid  remains  clear.     If  the  albuminose  be  present  only  in  small 

'  American  Journ.  Med.  Sci.,  Oct.  1854,  p.  319. 

*  Nouvelles  reclierches  relatives  a  Taction  du  sue  gastrique  sur  les  substances 
albuminoides. —  Gaz.  Hebd.  9  F^vrier,  1855,  p.  103. 


112  DIGESTION.  , 

quantity,  an  incomplete  reduction  of  the  copper  takes  place,  so  that 
the  mixture  becomes  opaline  and  cloudy,  but  still  without  any  well 
marked  deposit.  This  interference  will  take  place  when  sugar  is 
present  in  very  large  proportion.  We  have  found  that  in  a  mix- 
ture of  honey  and  gastric  juice  in  equal  volumes,  no  reduction  of 
copper  takes  place  on  the  application  of  Trommer's  test.  It  is 
remarkable,  however,  that  if  such  a  mixture  be  previously  diluted 
with  an  equal  quantity  of  water,  the  interference  does  not  take 
place,  and  the  copper  is  deposited  as  usual. 

Usually  this  peculiar  reaction,  now  that  we  are  acquainted  with 
its  existence,  will  not  practically  prevent  the  detection  of  sugar, 
when  present ;  since  the  presence  of  the  sugar  is  distinctly  indi- 
cated by  the  change  of  color,  as  above  mentioned,  from  purple  to 
yellow,  though  the  copper  may  not  be  thrown  down  as  a  precipi- 
tate. All  possibility  of  error,  furthermore,  may  be  avoided  by 
adopting  the  following  precautions.  The  purple  color,  already  men- 
tioned, will,  in  the  first  place,  serve  to  indicate  the  presence  of  the 
albuminoid  ingredient  in  the  suspected  fluid.  The  mixture  should 
then  be  evaporated  to  dryness,  and  extracted  with  alcohol,  in  order 
to  eliminate  the  animal  matters.  After  that,  a  watery  solution  of 
the  sugar  contained  in  the  alcoholic  extract  will  react  as  usual  with 
Trommer's  test,  and  reduce  the  oxide  of  copper  without  difficulty. 

Another  remarkable  property  of  gastric  juice  containing  albu- 
minose,  which  is  not,  however,  peculiar  to  it,  but  common  to  many 
other  animal  fluids,  is  that  of  interfering  with  the  m.utual  reaction 
of  starch  and  iodine.  If  5j  of  such  gastric  juice  be  mixed  with  3j 
of  iodine  water  and  boiled  starch  be  subsequently  added,  no  blue 
color  is  produced;  though  if  a  larger  quantity  of  iodine  water  be 
added,  or  if  the  tincture  be  used  instead  of  the  aqueous  solution, 
the  superabundant  iodine  then  combines  with  the  starch,  and  pro- 
duces the  ordinary  blue  color.  This  property,  like  that  described 
above,  is  not  possessed  by  pure,  colorless,  gastric  juice,  taken  from 
the  empty  stomach,  but  is  acquired  by  it  on  being  digested  with 
albuminoid  substances. 

Another  important  action  which  takes  place  in  the  stomach, 
beside  the  secretion  of  the  gastric  juice,  is  the  peristaltic  movement 
of  the  organ.  This  movement  is  accomplished  by  the  alternate 
contraction  and  relaxation  of  the  longitudinal  and  circular  fibres 
of  its  muscular  coat.  The  motion  is  minutely  described  by  Dr. 
Beaumont,  who  examined  it  both  by  watching  the  movements  of 
the  food  through  the  gastric  fistula,  and  also  by  introducing  into 


THE    GASTRIC    JUICE,   AND    STOMACH    DIGESTION.      113 

the  stomach  the  bulb  and  stem  of  a  thermometer.  According  to 
his  observations,  when  the  food  first  passes  into  the  stomach,  and 
tlie  secretion  of  the  gastric  juice  commences,  the  muscular  coat, 
which  was  before  quiescent,  is  excited  and  begins  to  contract  ac- 
tively. The  contraction  takes  place  in  such  a  manner  that  the 
food,  after  entering  the  cardiac  orifice  of  the  stomach,  is  first  car- 
ried to  the  left,  into  the  great  pouch  of  the  organ,  thence  downward 
and  along  the  great  curvature  to  the  pyloric  portion.  At  a  short 
distance  from  the  p^dorus.  Dr.  B.  often  found  a  circular  constric- 
tion of  the  parietes,  by  which  the  bulb  of  the  thermometer  was 
gently  grasped  and  drawn  toward  the  pylorus,  at  the  same  time 
giving  a  twisting  motion  to  the  stem  of  the  instrument,  by  which 
it  was  rotated  in  his  fingers.  In  a  moment  or  two,  however,  this 
constriction  was  relaxed,  and  the  bulb  of  the  thermometer  again 
released,  and  carried  together  with  the  food  along  the  small  curva- 
ture of  the  organ  to  its  cardiac  extremity.  This  circuit  was  re- 
peated so  long  as  anyibod  remained  in  the  stomach;  but  as  the 
liquefied  portions  were  successively  removed  toward  the  end  of 
digestion  it  became  less  active,  and  at  last  ceased  altogether  when 
the  stomach  had  become  completely  empty,  and  the  organ  returned 
to  its  ordinary  quiescent  condition. 

It  is  easy  to  observe  the  muscular  action  of  the  stomach  during 
digestion  in  the  dog,  by  the  assistance  of  a  gastric  fistula,  artificially 
established.  If  a  metallic  catheter  be  introduced  through  the 
fistula  when  the  stomach  is  empty,  it  must  usually  be  held  care- 
fully in  place,  or  it  will  fall  out  by  its  own  weight.  But  immedi- 
ately upon  the  introduction  of  food,  it  can  be  felt  that  the  catheter 
is  grasped  and  retained  with  some  force,  by  the  contraction  of  the 
muscular  coat.  A  twisting  or  rotatory  motion  of  its  extremity 
may  also  be  frequently  observed,  similar  to  that  described  by  Dr. 
Beaumont.  This  peristaltic  action  of  the  stomach,  however,  is  a 
gentle  one,  and  not  at  all  active  or  violent  in  character.  We  have 
never  seen,  in  opening  the  abdomen,  any  such  energetic  or  exten- 
sive contractions  of  the  stomach,  even  when  full  of  food,  as  may 
be  easily  excited  in  the  small  intestine  by  the  mere  contact  of  the 
atmosphere,  or  by  pinching  them  with  the  blades  of  a  forceps. 
This  action  of  the  stomach,  nevertheless,  though  quite  gentle,  is 
sufficient  to  produce  a  constant  churning  movement  of  the  masti- 
cated food,  by  which  it  is  carried  back  and  forward  to  every  part 
of  the  stomach,  and  rapidly  incorporated  with  the  gastric  juice 
which  is  at  the  same  time  poured  out  by  the  mucus  membrane ;  so 
8 


114  DIGESTION. 

that  the  digestive  fluid  is  made  to  penetrate  equally  every  part  of 
the  alimentary  mass,  and  the  digestion  of  all  its  albuminous  ingre- 
dients goes  on  simultaneously.  This  gentle  and  continuous  move- 
ment of  the  stomach  is  one  which  cannot  be  successfully  imitated 
in  experiments  on  artificial  digestion  with  gastric  juice  in  test-tubes; 
and  consequently  the  process,  under  these  circumstances,  is  never 
so  rapid  or  so  complete  as  when  it  takes  place  in  the  interior  of  the 
stomach. 

The  length  of  time  which  is  required  for  digestion  varies  in 
different  species  of  animals.  In  the  carnivora  a  moderate  meal  of 
fresh  uncooked  meat  requires  from  nine  to  twelve  hours  for  its 
complete  solution  and  disappearance  from  the  stomach.  According 
to  Dr.  Beaumont,  the  average  time  required  for  digestion  in  the 
human  subject  is  considerably  less;  varying  from  one  hour  to  five 
hours  and  a  half,  according  to  the  kind  of  food  employed.  This 
is  probably  owing  to  the  more  complete  mastication  of  the  food 
which  takes  place  in  man,  than  in  the  carnivorous  animals.  By 
examining  the  contents  of  the  stomach  at  various  intervals  after 
feeding.  Dr.  Beaumont  made  out  a  list,  showing  the  comparative 
digestibility  of  different  articles  of  food,  of  which  the  following  are 
the  most  important: — 

Time  required  for  digestion,  according  to  Dr.  Beaumont: — 

Kind  of  Food.  Hours.     Minutes. 

Pig's  feet 1  00 

Tripe 1  00 

Trout  (broiled) 1  30 

Venison  steak     ........  1  35 

Milk 2  00 

Roasted  turkey 2  ^       30 

"        beef 3  00 

"        mutton  ........  3  15 

Veal  (broiled) 4  00 

Salt  beef  (boiled) .4  15 

Roasted  pork 5  15 

The  comparative  digestibility  of  different  substances  varies  more 
or  less  in  different  individuals  according  to  temperament ;  but  the 
above  list  undoubtedly  gives  a  correct  average  estimate  of  the  time 
required  for  stomach  digestion  under  ordinary  conditions. 

A  very  interesting  question  is  that  which  relates  to  the  total 
gwanfe'^y  of  gastric  juice  secreted  daily.  Whenever  direct  experi- 
ments have  been  performed  with  a  view  of  ascertaining  this  point, 
their  results  have  given  a  considerably  larger  quantity  than  was 
anticipated.    Bidder  and  Schmidt  found  that,  in  a  dog  weighing 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION.      115 

34  pounds,  tliey  were  able  to  obtain  by  separate  experiments,  con- 
suming in  all  12  hours,  one  pound  and  three-quarters  of  gastric 
juice.  The  total  quantity,  therefore,  for  24  hours,  in  the  same 
animal,  would  be  3|  pounds;  and,. by  applying  the  same  calcula- 
tion to  a  man  of  medium  size,  the  authors  estimate  the  total  daily 
quantity  in  the  human  subject  as  but  little  less  than  14  pounds 
(av.).  This  estimate  is  probably  not  an  exaggerated  one.  In  order 
to  determine  the  question,  however,  if  possible,  in  a  different  way, 
we  adopted  the  following  plan  of  experiment  with  the  gastric  juice 
of  the  dog.  It  was  first  ascertained,  by  direct  experiment,  that  the 
fresh  lean  meat  of  the  bullock's  heart  loses,  by  complete  desicca- 
tion, 78  per  cent,  of  its  weight.  800  grains  of  such  meat,  cut  into 
small  pieces,  were  then  digested  for  ten  hours,  in  |iss  of  gastric 
juice  at  100°  F.;  the  mixture  being  thoroughly  agitated  as  often 
as  every  hour,  in  order  to  insure  the  digestion  of  as  large  a  quan- 
tity of  meat  as  possible.  The  meat  remaining  undissolved  was 
then  collected  on  a  previously  weighed  filter,  and  evaporated  to 
dryness.  The  dry  residue  weighed  55  grains.  This  represented, 
allowing  for  the  loss  by  evaporation,  250  grains  of  the  meat,  in  its 
natural  moist  condition ;  50  grains  of  meat  were  then  dissolved  by 
siss  of  gastric  juice,  or  33  J  grains  per  ounce. 

From  these  data  we  can  form  some  idea  of  the  large  quantity  of 
gastric  juice  secreted  in  the  dog  during  the  process  of  digestion. 
One  pound  of  meat  is  only  a  moderate  meal  for  a  medium-sized 
animal ;  and  yet,  to  dissolve  this  quantity,  no  less  than  thirteen  pints 
of  gastric  juice  will  be  necessary.  This  quantity,  or  any  approxi- 
mation to  it,  would  be  altogether  incredible  if  we  did  not  recollect 
that  the  gastric  juice,  as  soon  as  it  has  dissolved  its  quota  of  food, 
is  immediately  reabsorbed,  and  again  enters  the  circulation,  together 
with  the  alimentary  substances  jsvhich  it  holds  in  solution.  The 
secretion  and  reabsorption  of  the  gastric  juice  then  go  on  simulta- 
neously ;  and  the  fluids  which  the  blood  loses  by  one  process  are 
incessantly  restored  to  it  by  the  other.  A  very  large  quantity, 
therefore,  of  the  secretion  may  be  poured  out  during  the  digestion 
of  a  meal,  at  an  expense  to  the  blood,  at  any  one  time,  of  only  two 
or  three  ounces  of  fluid.  The  simplest  investigation  shows  that 
the  gastric  juice  does  not  accumulate  in  the  stomach  in  any  con- 
siderable quantity  during  digestion ;  but  that  it  is  gradually 
secreted  so  long  as  any  food  remains  undissolved,  each  portion,  as 
it  is  digested,  being  disposed  of  by  reabsorption,  together  with  its 
solvent  fluid.     There  is  accordingly,  during  digestion,  a  constant 


116  DIGESTION. 

circulation  of  the  digestive  fluids  from  the  bloodvessels  to  the 
alimentary  canal,  and  from  the  alimentary  canal  back  again  to  the 
bloodvessels. 

That  this  circulation  really  does  take  place  is  proved  by  the  fol- 
lowiog  facts :  First,  if  a  dog  be  killed  some  hours  after  feeding, 
there  is  never  more  than  a  very  small  quantity  of  fluid  found  in 
the  stomach,  just  sufficient  to  smear  over  and  penetrate  the  half 
digested  pieces  of  meat ;  and,  secondly,  in  the  living  animal,  gastric 
juice,  drawn  from  the  fistula  five  or  six  hours  after  digestion  has 
been  going  on,  contains  little  or  no  more  organic  matter  in  solution 
than  that  extracted  fifteen  to  thirty  minutes  after  the  introduction 
of  food.  It  has  evidently  been  freshly  secreted ;  and,  in  order  to 
obtain  gastric  juice  saturated  with  alimentary  matter,  it  must  be 
artificially  digested  with  food  in  test  tubes,  where  this  constant 
absorption  and  renovation  cannot  take  place. 

An  unnecessary  difficulty  has  sometimes  been  felt  in  understand- 
ing how  it  is  that  the  gastric  juice,  which  digests  so  readily  all 
albuminous  substances,  should  not  destroy  the  walls  of  tbe  stomach 
itself,  which  are  composed  of  similar  materials.  This,  in  fact,  was 
brought  forward  at  an  early  day,  as  an  insuperable  objection  to  the 
doctrine  of  Reaumur  and  Spallanzani,  that  digestion  was  a  process 
of  chemical  solution  performed  by  a  digestive  fluid.  It  was  said 
to  be  impossible  that  a  fluid  capable  of  dissolving  animal  matters 
should  be  secreted  by  the  walls  of  the  stomach  without  attacking 
them  also,  and  destroying  the  organ  by  which  it  was  produced. 
Since  that  time,  various  complicated  hypotheses  have  been  framed, 
in  order  to  reconcile  these  apparently  contradictory  facts.  The  true 
explanation,  however,  as  we  believe,  lies  in  this — that  the  process 
of  digestion  is  not  a  simple  solution,  but  a  catalytic  transformation 
of  the  alimentary 'substances,  produced  by  contact  with  the  pep- 
sine  of  the  gastric  juice.  We  know  that  all  the  organic  sub- 
stances in  the  living  tissues  are  constantly  undergoing,  in  the 
process  of  nutrition,  a  series  of  catalytic  changes,  which  are  charac- 
teristic of  the  vital  operations,  and  which  are  determined  by  the 
organized  materials  with  which  they  are  in  contact,  and  by  all  the 
other  conditions  present  in  the  living  organism.  These  changes, 
therefore,  of  nutrition,  secretion,  &c.,  necessarily  exclude  for  the 
time  all  other  catalyses,  and  take  precedence  of  them.  In  the  same 
way,  any  dead  organic  matter,  exposed  to  warmth,  air,  and  moist- 
ure, putrefies;  but  if  immersed  in  gastric  juice,  at  the  same 
temperature,  the  putrefactive  changes  are  stopped  or  altogether 


THE    GASTRIC    JUICE,    AND    STOMACH    DIGESTION.      117 

prevented,  because  the  catalytic  actions,  excited  by  the  gastric 
juice,  take  precedence  of  those  which  constitute  putrefaction.  For 
a  similar  reason,  the  organic  ingredient  of  the  gastric  juice,  which 
acts  readily  on  dead  animal  matter,  has  no  effect  on  the  living 
tissues  of  the  stomach,  because  they  are  already  subject  to  other 
catalytic  influences,  which  exclude  those  of  digestion,  as  well  as 
those  of  putrefaction.  As  soon  as  life  departs,  however,  and  the 
peculiar  actions  taking  place  in  the  living  tissues  come  to  an  end 
with  the  stoppage  of  the  circulation,  the  walls  of  the  stomach  are 
really  attacked  by  the  gastric  juice  remaining  in  its  cavity,  and 
are  more  or  less  completely  digested  and  liquefied.  In  the  human 
subject,  it  is  rare  to  make  an  examination  of  the  body  twenty-four 
or  thirty-six  hours  after  death,  without  finding  the  mucous  mem- 
brane of  the  great  pouch  of  the  stomach  more  or  less  softened  and 
disintegrated  from  this  cause.  Sometimes  the  mucous  membrane 
is  altogether  destroyed,  and  the  submucous  cellular  layer  exposed ; 
and  occasionally,  when  death  has  taken  place  suddenly  during 
active  digestion,  while  the  stomach  contained  an  abundance  of 
gastric  juice,  all  the  coats  of  the  organ  have  been  found  destroyed, 
and  a  perforation  produced  leading  into  the  peritoneal  cavity. 
These  post-mortem  changes  show  that,  after  death,  the  gastric 
juice  really  dissolves  the  coats  of  the  stomach  without  difficulty. 
But  during  life,  the  chemical  changes  of  nutrition,  which  are  going 
on  in  their  tissues,  protect  them  from  its  influence,  and  effectually 
preserve  their  integrity. 

The  secretion  of  the  gastric  juice  is  much  influenced  by  nervous 
conditions.  It  was  noticed  by  Dr.  Beaumont,  in  his  experiments 
upon  St.  Martin,  that  irritation  of  the  temper,  and  other  moral 
causes,  would  frequently  diminish  or  altogether  suspend  the  supply 
of  the  gastric  fluids.  Any  febrile  action  in  the  system,  or  any 
unusual  fatigue,  was  liable  to  exert  a  similar  effect.  Every  one  is 
aware  how  readily  any  mental  disturbance,  such  as  anxiety,  anger, 
or  vexation,  will  take  away  the  appetite  and  interfere  with  diges- 
tion. Any  nervous  impression  of  this  kind,  occurring  at  the  com- 
■mencement  of  digestion,  seems  moreover  to  produce  some  change 
which  has  a  lasting  effect  upon  the  process ;  for  it  is  very  often 
noticed  that  when  any  annoyance,  hurry,  or  anxiety  occurs  soon 
after  the  food  has  been  taken,  though  it  may  last  only  for  a  few 
moments,  the  digestive  process  is  not  only  liable  to  be  suspended 
for  the  time,  but  to  be  permanently  disturbed  during  the  entire, 
day.     In  order  that  digestion,  therefore,  may  go  on  properly  in  the 


118  .  DIGESTION. 

« 

stomacli,  food  must  be  taken  only  when  the  appetite  demands  it ; 
it  should  also  be  thoroughly  masticated  at  the  outset ;  and,  finally, 
both  mind  and  body,  particularly  during  the  commencement  of  the 
process,  should  be  free  from  any  unusual  or  disagreeable  excite- 
ment. 


INTESTINAL  JUICES,  AND  THE  DIGESTION  OF  SUGAR  AND  STARCH. 

From  the  stomach,  those  portions  of  the  food  which  have  not 
already  suffered  digestion,  pass  into  the  third  division  of  the  ali- 
mentary canal,  viz.,  the  small  intestine.  As  already  mentioned,  it 
is  only  the  albuminous  matters  which  are  digested  jn  the  stomach. 
Cane  sugar,  it  is  true,  is  slowly  converted  by  the  gastric  juice,  out- 
side the  body,  into  glucose.  We  have  found  that  ten  grains  of 
cane  sugar,  dissolved  in  §ss  of  gastric  juice,  give  traces  of  glucose 
at  the  end  of  two  hours;  and  in  three  hours,  the  quantity  of  this 
substance  is  considerable.  It  cannot  be  shown,  however,  that  the 
gastric  juice  exerts  this  effect  on  sugar  during  ordinary  digestion. 
If  pure  cane  sugar  be  given  to  a  dog  with  a  gastric  fistula,  while 
digestion  of  meat  is  going  on,  it  disappears  in  from  two  to  three 
hours,  without  any  glucose  being  detected  in  the  fluids  withdrawn 
from  the  stomach.  It  is,  therefore,  either  directly  absorbed  under 
the  form  of  cane  sugar,  or  passes,  little  by  little,  into  the  duodenum, 
where  the  intestinal  fluids  at  once  convert  it  into  glucose. 

"It  is  equally  certain  that  starchy  .matters  are  not  digested  in  the 
stomach,  but  pass  unchanged  into  the  small  intestine.  Here  they 
meet  with  the  mixed  intestinal  fluids,  which  act  at  once  upon  the 
starch,  and  convert  it  rapidly  into  sugar.  The  intestinal  fluids, 
taken  from  the  duodenum  of  a  recently  killed  dog,  exert  this 
transforming  action  upon  starch  with  the  greatest  promptitude,  if 
mixed  with  it  in  a  test-tube  and  kept  at  the  temperature  of  100°  F. 
Starch  is  converted  into  sugar  by  this,  means  much  more  rapidly 
and  certainly  than  by  the  saliva;  and  experiment  shows  that  the 
intestinal  fluids  are  the  active  agents  in  its  digestion  during  life. 
If  a  dog  be  fed  with  a  mixture  of  meat  and  boiled  starch,  and  killed 
a  short  time  after  the  meal,  the  stomach  is  found  to  contain  starch 
but  no  sugar;  while  in  the  small  intestine  there  is  an  abundance  of 
sugar,  and  but  little  or  no  starch.  If  some  observers  have  failed 
to  detect  sugar  in  the  intestine  after  feeding  the  animal  with 
starch,  it  is  because  they  have  delayed  the  examination  until  too 


INTESTINAL    JUICES,    DIGESTION    OF    SUGAR,    ETC.       119 


late.  For  it  is  remarkable  how  rapidly  starchy  substances,  if 
previously  disintegrated  by  boiling,  are  disposed  of  in  the  digest- 
ive process.  If  a  dog,  for  example,  be  fed  as  above  with  boiled 
starch  and  meat,  while  some  of  the  meat  remains  in  the  stomach 
for  eight,  nine,  or  ten  hours,  the  starch  begins  immediately  to 
pass  into  the  intestine,  where  it  is  at  once  converted  into  sugar, 
and  then  as  rapidly  absorbed.  The  whole  of  the  starch  may 
be  converted  into  sugar,  and  completely  absorbed,  in  an  hour's 
time.  We  have  even  found,  at  the  end  of  three-quarters  of  an 
hour,  after  a  tolerably  full  meal  of  boiled  starch  and  meat,  that  all 
trace  of  both  starch  and  sugar  had  disappeared  from  both  stomach 
and  intestine.  The  rapidity  with  which  this  passage  of  the  starch 
into  the  duodenum  takes  place  varies,  to  some  extent,  in  different 
animals,  according  to  the  general  activity  of  the  digestive  appa- 
ratus; but  it  is  always  a  comparatively  rapid  process,  when  the 
starch  is  already  liquefied  and  is  administered  in  a  pure  form. 
There  can  be  no  doubt  that  the  natural  place  for  the  digestion  of 
starchy  matters  is  the  small  intestine,  and  that  it  is  accomplished 
by 'the  action  of  the  intestinal  juices. 

Our  knowledge  is  not  very  complete  with  regard  to  the  exact 
nature  of  the  fluids  by  which  this  digestion  of  the  starch  is  accom- 
plished. The  juices  taken  from  the  duodenum  are  generally  a 
mixture  of  three  different  secretions,  viz.,  the  bile,  the  pancreatic 
fluid,  and  the  intestinal  juice  proper.  Of  these,  the  bile  may  be 
left  out  of  the  question;  since  it  does  not,  when  in  a  pure  state, 
exert  any  digestive  action  on  starch.  The  pancreatic  juice,  on  the 
other  hand,  has  the  property  p.     gi 

of  converting  starch  into  su- 
gar; but  it  is  not  known 
whether  this  fluid  be  always 
present  in  the  duodenum. 
The  true  intestinal  juice  is  the 
product  of  two  sets  of  glan- 
dular organs,  seated  in  the 
substance  of  or  beneath  the 
mucous  membrane,  viz.,  the 
follicles  of  LieberkiJhn  and 
the  glands  of  Brunner.  The 
first  of  these,  or  Lieberkiihn's 
follicles  (Fig.  31),  are  the  most 
numerous.    They  are  simple,       follicles  op  lieberkuhx,  from  smaii  in- 

''  ^  testine  of  Pig. 


120 


DIGESTION. 


Dearly  straight  tubules,  lined  witli  columnar  epithelium,  and  some- 
what similar  in  their  appearance  to  the  follicles  of  the  pyloric 
portion  of  the  stomach.  They  occupy  the  whole  thickness  of  the 
mucous  membrane,  and  are  found  in  great  numbers  throughout  the 
entire  length  of  the  small  and  large  intestine. 

The  glands  of  Brunner  (Fig.  32),  or  the  duodenal  glandulse,  as 

they  are  sometimes  called,  are 
Fig.  32.  ^  confined  to  the  upper  part  of 

the  duodenum,  where  they 
exist,  as  a  closely  set  layer, 
in  the  deeper  portion  of  the 
mucous  membrane,  extending 
downward  a  short  distance 
from  the  pylorus.  They  are 
composed  of  a  great  number 
of  rounded  follicles,  or  culs-de- 
sac,  clustered  round  a  central 
excretory  duct.  Each  follicle 
consists  of  a  delicate  mem- 
branous wall,  lined  with  glan- 
dular epithelium,  and  covered 
on  its  surface  with  small,  dis- 
tinctly marked  nuclei.  The 
follicles  collected  round  each  duct  are  bound  together  by  a  thin 
layer  of  areolar  tissue,  and  covered  with  a  plexus  of  capillary 
bloodvessels. 

The  intestinal  jaice,  which  is  the  secreted  product  of  the  above 
glandular  organs,  has  been  less  successfully  studied  than  the  other 
digestive  fluids,  owing  to  the  difficulty  of  obtaining  it  in  a  pure 
state.  The  method  usually  adopted  has  been  to  make  an  opening 
in  the  abdomen  of  the  living  animal,  take  out  a  loop  of  intestine, 
empty  it  by  gentle  pressure,  and  then  to  shut  off  a  portion  of  it 
from  the  rest  of  the  intestinal  cavity  by  a  couple  of  ligatures, 
situated  six  or  eight  inches  apart;  after  which  the  loop  is  returned 
into  the  abdomen,  and  the  external  wound  closed  by  sutures. 
After  sis  or  eight  hours  the  animal  is  killed,  and  the  fluid,  which 
has  collected  in  the  isolated  portion  of  intestine,  taken  out  and 
examined.  The  above  was  the  method  adopted  by  Frerichs.  Bid- 
der and  Schmidt,  in  order  to  obtain  pure  intestinal  juice,  first  tied 
the  biliary  and  pancreatic  ducts,  so  that  both  the  bile  and  the  pan- 
creatic juice  should  be  shut  out  from  the  intestine,  and  then  estab- 


Portion   of   one    of   Brtsner's    Duodexal 
Glands,  from  Human  Intestine. 


PANCREATIC    JUICE,  AND    THE    DIGESTION    OF    FAT.        121 

lished  an  intestinal  fistula  below,  from  which  they  extracted  the 
fluids  which  accumulated  in  the  cavity  of  the  gut.  From  the  great 
abundance  of  the  follicles  of  Lieberkiihn,  we  should  expect  to  find 
the  intestinal  juice  secreted  in  large  quantity.  It  appears,  however, 
in  point  of  fact,  to  be  quite  scanty,  as  the  quantity  collected  in  the 
above  manner  by  experimenters  has  rarely  been  sufficient  for  a 
thorough  examination  of  its  properties.  It  seems  to  resemble  very 
closely,  in  its  physical  characters,  the  secretion  of  the  mucous  fol- 
licles of  the  mouth.  It  is  colorless  and  glassy  in  appearance,  viscid 
and  mucous  in  consistency,  and  has  a  distinct  alkaline  reaction. 
It  has  the  property,  when  pure,  as  well  as  when  mixed  with  other 
secretions,  of  rapidly  converting  starch  into  sugar,  at  the  tempe- 
rature of  the  living  body. 


PANCREATIC  JUICE,  AND  THE  DIGESTION  OF  FAT, 

The  only  remaining  ingredients  of  the  food  that  require  digestion 
are  the  oily  matters.  These  are  not  affected,  as  we  have  already 
stated,  by  contact  with  the  gastric  juice ;  and  examination  shows, 
furthermore,  that  they  are  not  digested  in  the  stomach.  So  long 
as  they  remain  in  the  cavity  of  this  organ  they  are  unchanged  in 
their  essential  properties.  They  are  merely  melted  by  the  warmth 
of  the  stomach,  and  set  free  by  the  solution  of  the  vesicles,  fibres, 
or  capillary  tubes  in  which  they  are  contained,  or  among  which 
they  are  entangled ;  and  are  still  readily  discernible  by  the  eye, 
floating  in  larger  or  smaller  drops  on  the  surface  of  the  semi-fluid 
alimentary  mass.  Yery  soon,  however,  after  its  entrance  into  the 
intestine,  the  oily  portion  of  the  food  loses  its  characteristic  ap- 
pearance, and  is  converted  into  a  white,  opaque  emulsion,  which  is 
gradually  absorbed.  This  emulsion  is  termed  the  chyle^  and  is 
always  found  in  the  small  intestine  during  the  digestion  of  fat, 
entangled  among  the  valvulse  conniventes,  and  adhering  to  the 
surface  of  the  villi.  The  digestion  of  the  oil,  however,  and  its  con- 
version into  chyle,  does  not  take  place  at  once  upon  its  entrance 
into  the  duodenum,  but  only  after  it  has  passed  the  orifices  of  the 
pancreatic  and  biliary  ducts.  Since  these  ducts  almost  invariably 
open  into  the  intestine  at  or  near  the  same  point,  it  was  for  a  long 
time  dif&cult  to  decide  by  which  of  the  two  secretions  the  digestion 
of  the  oil  was  accomplished.  M.  Bernard,  however,  first  threw 
some  light  on  this  question  by  experimenting  on  some  of  the  lower 


122  DIGESTION. 

animals,  in  whidi  the  two  ducts  open  separately.  In  the  rabbit, 
for  example,  the  biliary  duct  opens  as  usual  just  below  the  pylorus, 
while  the  pancreatic  duct  communicates  with  the  intestine  some 
eight  or  ten  inches  lower  down.  Bernard  fed  these  animals  "with 
substances  containing  oil,  or  injected  melted  butter  into  the  stomach; 
and,  on  killing  them  afterward,  found  that  there  was  no  chyle  in 
the  intestine  between  the  opening  of  the  biliary  and  pancreatic 
ducts,  but  that  it  was  abundant  immediately  below  the  orifice  of 
the  latter.  Above  this  point,  also,  he  fo'und  the  lacteals  empty  or 
transparent,  while  below  it  they  were  full  of  white  and  opaque 
chyle.  The  result  of  these  experiments,  which  have  since  been 
confirmed  by  Prof.  Samuel  Jackson  of  Philadelphia,'  lead  to  the 
conclusion  that  the  pancreatic  fluid  is  the  active  agent  in  the  diges- 
tion of  oily  substances;  and  an  examination  of  the  properties  of 
this  secretion,  when  obtained  in  a  pure  state  from  the  living  animal, 
fully  confirm  the  above  opinion. 

In  order  to  obtain  pancreatic  juice  from  the  dog,  the  animal 
must  be  etherized  soon  after  digestion  has  commenced,  an  incision 
made  in  the  upper  part  of  the  abdomen,  a  little  to  the  right  of  the 
median  line,  and  a  loop  of  the  duodenum,  together  with  the  lower 
extremity  of  the  pancreas  which  lies  adjacent  to  it,  drawn  out  at 
the  external  wound.  The  pancreatic  duct  is  then  to  be  exposed 
and  opened,  and  a  small  silver  canula  inserted  into  it  and  secured 
by  a  ligature.  The  whole  is  then  returned  into  the  abdomen  and 
the  wound  closed  by  sutures,  leaving  only  the  end  of  the  canula 
projecting  from  it.  In  the  dog  there  are  two  pancreatic  ducts, 
situated  from  half  an  inch  to  an  inch  apart.  The  lower  one  of 
these,  which  is  usually  the  larger  of  the  two,  is  the  one  best  adapted 
for  the  insertion  of  the  canula.  After  the  eSects  of  etherization 
have  passed  off,  and  the  digestive  process  has  recommenced,  the 
pancreatic  juice  begins  to  run  from  the  orifice  of  the  canula,  at  first 
very  slowly  and  in  drops.  Sometimes  the  drops  follow  each  other 
with  rapidity  for  a  few  moments,  and  then  an  interval  occurs  during 
which  the  secretion  seems  entirely  suspended.  After  a  time  it 
recommences,  and  continues  to  exhibit  similar  fluctuations  during 
the  whole  course  of  the  experiment.  Its  flow,  however,  is  at  all 
times  scanty,  compared  with  that  of  the  gastric  juice  ;  and  we  have 
never  been  able  to  collect  at  most  more  than  five  or  six  drachms 
during  a  period  of  several  hours.     Bidder  and  Schmidt  obtained 

'  American  Journ.  Med.  Sci.,  Oct.  1854. 


PANCREATIC    JUICE,  AND    THE    DIGESTION    OF    FAT.     123 

on  an  average,  from  a  dog  weighing  44  pounds,  14|-  grains  of  pan- 
creatic juice  per  hour ;  and  they  calculate  from  this  that  the  average 
daily  quantity  in  the  human  subject  is  rather  less  than  2500  grains, 
or  a  little  over  one-third  of  a  pound  avoirdupois. 

Pancreatic  juice  obtained  by  the  above  process  is  a  clear,  color- 
less, somewhat  viscid  fluid,  with  a  distinct  alkaline  reaction.  Its 
composition,  according  to  the  analysis  of  Bidder  and  Schmidt,  is 
as  follows : — 

Composition  of  Pancreatic  Juice. 

Water 900.76 

Organic  matter  (pancreatine)    .......  90.38 

Chloride  of  sodium    .........  7.36 

Free  soda           ..........  0.32 

Phosphate  of  soda 0.45 

Sulphate  of  soda        . 0.10      . 

Sulphate  of  potass ■     .         .  0.02 

r  Lime 0.54 

Combinations  of     }  Magnesia  .......  0.05 

y  Oxide  of  iron 0.02 

1000.00 

The  most  important  ingredient  of  the  pancreatic  juice  is  its 
organic  matter  or  pancreatine.  It  will  be  seen  that  this  is  much 
more  abundant  in  proportion  to  the  other  ingredients  of  the  secre- 
tion than  the  organic  matter  of  any  other  digestive  fluid.  It  is 
coagulable  by  heat;  and  the  pancreatic  juice  often  solidifies  com- 
pletely on  boiling,  like  white  of  egg,  so  that  not  a  drop  of  fluid 
remains  after  its  coagulation.  It  is  precipitated,  furthermore,  by 
nitric  acid  and  by  alcohol,  and  also  by  sulphate  of  magnesia  in 
excess.  By  this  last  property,  it  may  be  distinguished  from  albu- 
men, which  is  not  affected  by  contact  with  sulphate  of  magnesia. 

Fresh  pancreatic  juice,  brought  into  contact  with  oily  matters  at 
the  temperature  of  the  body,  exerts  upon  them,  as  was  first  noticed 
by  Bernard,  a  very  peculiar  effect.  It  disintegrates  them,  and  re- 
duces them  to  a  state  of  complete  emulsion,  so  that  the  mixture  is 
at  once  converted  into  a  white,  opaque,  creamy-looking  fluid.  This 
effect  is  instantaneous  and  permanent,  and  only  requires  that  the 
two  substances  be  well  mixed  by  gentle  agitation.  It  is  singular 
that  some  of  the  German  observers  should  deny  that  the  pancreatic 
juice  possesses  this  property,  of  emulsioning  fat,  to  a  greater  extent 
than  the  bile  and  some  other  digestive  fluids;  and  should  state  that 
although,  when  shaken  up  with  oil,  outside  the  body,  it  reduces 
the  oily  particles  to  a  state  of  extreme  minuteness,  the  emulsion 


124  DIGESTION. 

is  not  permanent,  and  the  oily  particles  "soon  separate  again  on 
the  surface.'"  We  have  frequently  repeated  this  experiment  with 
different  specimens  of  pancreatic  juice  obtained  from  the  dog,  and 
have  never  failed  to  see  that  the  emulsion  produced  by  it  is  by 
far  more  prompt  and  complete  than  that  which  takes  place  with 
saliva,  gastric  juice,  or  bile.  The  effect  produced  by  these  fluids  is 
in  fact  altogether  insignificant,  in  comparison  with  the  prompt  and 
energetic  action  exerted  by  the  pancreatic  juice.  The  emulsion 
produced  with  the  latter  secretion  may  be  kept,  furthermore,  for  at 
least  twenty-four  hours,  according  to  our  observations,  without  any 
appreciable  separation  of  the  oily  particles,  or  a  return  to  their 
original  condition. 

The  pancreatic  juice,  therefore,  is  peculiar  in  its  action  on  oily 
substances,  and  reduces  them  at  once  to  the  condition  of  an  emul- 
sion. The  oil,  in  this  process,  does  not  suffer  any  chemical  altera- 
tion. It  is  not  decomposed  or  saponified,  to  any  appreciable  extent. 
It  is  simply  emulsioned;  that  is,  it  is  broken  up  into  a  state  of  minute 
subdivision,  and  retained  in  suspension  by  contact  with  the  organic 
matter  of  the  pancreatic  juice.  That  its  chemical  condition  is  not 
altered  is  shown  by  the  fact  that  it  is  still  soluble  in  ether,  which 
will  withdraw  the  greater  part  of  the  fat  from  a  mixture  of  oil  and 
pancreatic  juice,  as  well  as  from  the  chyle  in  the  interior  of  the 
intestine.  In  a  state  of  emulsion  the  fat,  furthermore,  is  capable 
of  being  absorbed,  and  its  digestion  may  be  then  said  to  be  accom- 
plished. 

We  find,  then,  that  the  digestion  of  the  food  is  not  a  simple 
operation,  but  is  made  up  of  several  different  processes,  which 
commence  successively  in  different  portions  of  the  alimentary 
canal.  In  the  first  place,  the  food  is  subjected  in  the  mouth  to  the 
physical  operations  of  mastication  and  insalivation.  Eeduced  to  a 
soft  pulp  and  mixed  abundantly  with  the  saliva,  it  passes,  secondly, 
into  the  stomach.  Here  it  excites  the  secretion  of  the  gastric  juice, 
by  the  influence  of  which  its  chemical  transformation  and  solution 
are  commenced.  If  the  meal  consist  wholly  or  partially  of  mus- 
cular flesh,  the  first  effect  of  the  gastric  juice  is  to  dissolve  the 
intervening  cellular  substance,  by  which  the  tissue  is  disintegrated 
and  the  muscular  fibres  separated  from  each  other.  Afterward 
the  muscular  fibres  themselves  become  swollen  and  softened  by 
the  imbibition  of  the  gastric  fluid,  and  are  finally  disintegrated 
and  liquefied.     In  the  small  intestine,  the  pancreatic  and  intestinal 

'  Lehmann's  Physiological  Chemistry.     Philada.  ed.,  vol.  i.  p.  507. 


PHENOMENA    OF    INTESTINAL    DIGESTION.  125 

juices  convert  the  starchy  ingredients  of  the  food  into  sugar,  and 
break  up  the  fatty  matters  into  a  fine  emulsion,  by  which  they 
are  converted  into  chyle. 

Although  the  separate  actions  of  these  digestive  fluids,  however, 
commence  at  different  points  of  the  alimentary  canal,  they  after- 
ward go  on  simultaneously  in  the  small  intestine ;  and  the  changes 
Avhich  take  place  here,  and  which  constitute  the  process  of  intestinal 
digestion,  form  at  the  same  time  one  of  the  most  complicated  and 
one  of  the  most  important  parts  of  the  whole  digestive  function. 

The  phenomena  of  intestinal  digestion  may  be  studied,  in  the 
dog,  by  killing  the  animal  at  various  periods  after  feeding,  and 
examining  the  contents  of  the  intestine.  We  have  also  succeeded, 
by  establishing,  in  the  same  animal,  an  artificial  intestinal  fistula, 
in  gaining  still  more  satisfactory  information  on  this  point.  The 
fistula  may  be  established,  for  this  purpose,  by  an  operation  precisely 
similar  to  that  already  described  as  employed  for  the  production  of 
a  permanent  fistula  in  the  stomach.  The  silver  tube  having  been 
introduced  into  the  lower  part  of  the  duodenum,  the  wound  is 
allowed  to  heal,  and  the  intestinal  secretions  may  then  be  with- 
drawn at  will,  and  subjected  to  examination  at  different  periods 
during  digestion. 

By  examining  in  this  way,  from  time  to  time,  the  intestinal 
fluids,  it  at  once  becomes  ^manifest  that  the  action  of  the  gastric 
juice,  in  the  digestion  of  albuminoid  substances,  is  not  confined  to 
the  stomach,  but  continues  after  the  food  has  passed  into  the  intes- 
tine. About  half  an  hour  after  the  injection  of  a  meal,  the  gastric 
juice  begins  to  pass  into  the  duodenum,  where  it  may  be  recognized 
by  its  strongly-marked  acidity,  and  by  its  peculiar  action,  already 
described,  in  interfering  with  Trommer's  test  for  grape  sugar.  It 
has  accordingly  already  dissolved  some  of  the  ingredients  of  the 
food  while  still  in  the  stomach,  and  contains  a  certain  quantity  of 
albuminose  in  solution.  It  soon  afterward,  as  it  continues  to  pass 
into  the  duodenum,  becomes  mingled  with  the  debris  of  muscular 
fibres,  fat  vesicles,  and  oil  drops;  substances  which  are  easily 
recognizable  under  the  microscope,  and  which  produce  a  grayish 
turbidity  in  the  fluid  drawn  from  the  fistula.  This  turbid  admix- 
ture becomes  thicker  and  thicker  from  the  second  to  the  tenth  or 
twelfth  hour;  after  which  the  intestinal  fluids  become  rapidly  less 
abundant,  and  finally  disappear  almost  entirely,  as  the  process  of 
digestion  comes  to  an  end. 

The  passage  of  disintegrated  muscular  tissue  into  the  intestine 


126 


DIGESTION. 


CosTENTS  OP  Stomach  dueixg  Digestion 
OF  Meat,  from  the  Dog. — a.  Fat  Vesicle,  filled  with 
opaque,  solid,  granular  fat.  b,  h.  Bits  of  partially  dis- 
integrated muscular  fibre,     c.  Oil  globules. 


may  also  be  shown,  as  already  mentioned,  by  killing  the  animal 
and  examining  the  contents  of  the  alimentary  canal.     During  the 

digestion  of  muscular  flesh 
^^s-  33.  2,xi(\  adipose  tissue,  the  sto- 

mach contains  masses  of  soft- 
ened meat,  smeared  over  with 
gastric  juice,  and  also  a  mo- 
derate quantity  of  grayish 
grumous  fluid,  with  an  acid 
reaction.  This  fluid  contains 
muscular  fibres,  isolated  from 
each  other,  and  more  or  less 
disintegrated  by  the  action 
of  the  gastric  juice.  (Fig.  33.) 
The  fat  vesicles  are  but  little 
or  not  at  all  altered  in  the 
stomach,  and  there  are  only 
a  few  free  oil  globules  to  be 
seen  floating  in  the  mixed 
fluids,  contained  in  the  cavity 
of  the  organ.  In  the  duodenum  the  muscular  fibres  are  further 
disintegrated.    (Fig.  3J:.)    They  become  very  much  broken  up,  pale 

and  transparent,  but  can  still 
^^^'  be  recognized  by  the  granu- 

lar markings  and  striations 
which  are  characteristic  of 
them.  The  fat  vesicles  also 
begin  to  become  altered  in 
the  duodenum..  The  solid 
granular  fat  of  beef,  and  simi- 
lar kinds  of  meat,  becomes 
liquefied  and  emulsioned;  and 
appears  under  the  form  of 
free  oil  drops  and  fatty  mole- 
cules; while  the  fat  vesicle 
itself  is  partially  emptied,  and 

From   Dtodexum  of  Dog,  ditrixg    Diges-  bcCOmeS     morC      Or     IcSS     Col- 

TiON   OF  Meat. — a.  Fat  vesicle,  with  its.  contents  ,             j          i     i      •       n     l        T„   j-U^ 

diminishing.     The  vesicle  is  beginning  to  shrivel  and  lapSCd  and  shriVClled.      In  the 

the  fat  breaking  up.     6,  6.    Disintegrated   muscular  middle  and  loWCr  partS  of  the 

fibre,     e,  c.  Oil  globules.  .              .            ,.p,.             n~            j      o/j\ 

intestine   (Figs.   3o   and   36) 
these  changes  continue.     The  muscular  fibres  become  constantly 


PHENOMENA    OF    INTESTINAL    DIGESTION. 


127 


Fig.  35. 


more  and  more  disintegrated,  and  a  large  quantity  of  granular 
debris  is  produced,  wliich  is  at  last  also  dissolved.  The  fat  also 
progressively  disappears,  and 
the  vesicles  may  be  seen  in 
the  lower  part  of  the  intes- 
tine, entirely  collapsed  and 
empty. 

In  this  way  the  digestion 
of  tlie  different  ingredients  of 
the  food  goes  on  in  a  con- 
tinuous manner,  from  the  sto- 
mach throughout  the  entire 
length  of  the  small  intestine. 
At  the  same  time,  it  results 
in  the  production  of  three 
diflerent  substances,  viz :  1st. 
Albuminose,  produced  by  the       ^        ,,  o         . 

'  '■  ...  From  Middle  of  Small  Intestine. — a,  a. 

action     of     the     gastric     juice      Fat  vesicles,  nearly  emptied  of  their  contents. 

on  the   albuminoid  matters; 


2d.  An  oily  emulsion,  pro- 
duced by  the  action  of  the 
pancreatic  juice  on  fat;  and, 
3d.  Sugar,  produced  from  the 
transformation  of  starch  by 
the  mixed  intestinal  fluids. 
These  substances  are  then 
ready  to  be  taken  up  into 
the  circulation  ;  and  the  next 
change  which  they  undergo, 
in  the  regular  course  of  the 
vital  processes,  is  that  of  ah- 
sorption.  This  process  will 
form  the  subject  of  the  next 
chapter. 


Fig.  36. 


From  last  quarter  of  Small  Intestine. 
-a,  a.  Fat  vesicles,  quite  empty  and  shrivelled. 


128 


ABSORPTION". 


CHAPTEK  VII. 


ABSORPTION. 


Beside  the  glands  of  Brunner  and  the  follicles  of  Lieberkiihii, 
already  described,  there  are,  in  the  inner  part  of  the  walls  of  the 

intestine,  certain    glandular- 


Fig.  37. 


One  of  the  closed  Follicles  of  Peter's 
Patches,  from  Small  Intestine  of  Pig.  Magnified 
50  diameters. 

Fig.  38. 


Glanduls;    Agminat;e,    from    Small  Intestine 
of  Pig.     Magnified  20  diameters. 


looking  bodies  which  are 
termed  "  glandulse  solitariae," 
and  "  glandulae  agminatse." 
The  glandulse  solitariae  are 
globular  or  ovoid  bodies, 
about  one-thirtieth  of  an  inch 
in  diameter,  situated  partly 
in,  and  partly  beneath,  the 
intestinal  mucous  membrane. 
Each  glandule  (Fig.  37)  is 
formed  of  an  investing  cap- 
sule, closed  on  all  sides,  and 
containing  in  its  interior  a 
soft  pulpy  mass,  which  con- 
sists of  minute  cellular  bodies, 
imbedded  in  a  homogeneous 
substance.  The  inclosed  mass 
is  penetrated  by  capillary 
bloodvessels,  which  penetrate 
through  the  investing  cap- 
sule, inosculate  freely  with 
each  other,  and  return  upon 
themselves  in  loops,  near  the 
centre  of  the  glandular  body. 
There  is  no  external  opening 
or  duct ;  in  fact,  the  contents 
of  the  vesicle,  being  pulpy 
and  vascular,  as  already  de- 
scribed, are  not  to  be  regarded 


ABSORPTION. 


129 


as  a  secretion,  but  as  constituting  a  kind  of  solid  glandular  tissue. 
The  gland ul^e  agminate  (Fig.  38),  or  "  Payer's  patches,"  as  they  are 
sometimes  called,  consist  of  aggregations  of  similar  globular  or 
ovoid  bodies,  found  most  abundantly  toward  the  lower  extremity  of 
the  small  intestine.  Both  the  solitary  and  agminated  glandules  are 
evidently  connected  with  the  lacteals  and  the  system  of  the  mesen- 
teric glands,  which  latter  organs  they  resemble  very  much  in  their 
minute  structure.  They  are  probably  to  be  regarded  as  the  first 
row  of  mesenteric  glands,  situated  in  the  walls  of  the  intestinal 
canal. 

Another  set  of  organs,  intimately  connected  with  the  process  of 
absorption,  are  the  villi  of  the  small  intestine.  These  are  conical 
vascular  eminences  of  the  mucous  membrane,  thickly  set  over  the 
whole  internal  surface  of  the  small  intestine.  In  the  upper  portion  of 
the  intestine,  they  are  flattened  and  triangular  in  form,  resembling 
somewhat  the  conical  projections  of  the  pyloric  portion  of  the  sto- 
mach. In  the  lower  part,  they  are  long  and  filiform,  and  often 
slightly  enlarged,  or  club-shaped,  at  their  free  extremity  (Fig.  89), 
and  frequently  attaining  the  length  of 
one-thirty-fifth  of  an  inch.  They  are 
covered  externally  with  a  layer  of 
columnar  epithelium,  similar  to  that 
which  lines  the  rest  of  the  intestinal 
mucous  membrane,  and  contain  in  their 
interior  two  sets  of  vessels.  The  most 
superficial  of  these  are  the  capillary 
bloodvessels,  which  are  supplied  in  each 
villus  by  a  twig  of  the  mesenteric 
artery,  and  which  form,  by  their  fre- 
quent inosculation,  an  exceedingly  close 
and  abundant  network,  almost  imme- 
diately beneath  the  epithelial  layer. 
The}^  unite  at  the  base  of  the  villus, 
and  form  a  minute  vein,  which  is  one 
of  the  commencing  rootlets  of  the  por- 
tal vein.  In  the  central  part  of  the  vil- 
lus, and  lying  nearly  in  its  axis,  there 
is  another  vessel,  with  thinner  and  more 
transparent  walls,  which  is  the  commencement  of  a  lacteal.  The 
precise  manner  in  which  the  lacteal  originates  in  the  extremity  of 
the  villus  is  not  known.  It  commences  near  the  apex,  either  by  a 
9 


Extremity  of  I  x  testis  a  i. 
Villus;  from  the  Dog. — u.  Layer  of 
epithelium,   b.  Bloodvessel,  c.  Lacteal 

vessel. 


130  ABSORPTION. 

blind  extremity  or  by  an  irregular  plexus,  passes,  in  a  straight  or 
somewhat  wavy  line,  toward  the  base  of  the  villus,  and  then  becomes 
continuous  with  a  small  twig  of  the  mesenteric  lacteals. 

The  villi  are  the  active  agents  in  the  process  of  absorption.  By 
their  projecting  form,  and  their  great  abundance,  they  increase  enor- 
mously the  extent  of  surface  over  which  the  digested  fluids  come 
in  contact  with  the  intestinal  mucous  membrane,  and  increase,  also, 
to  a  corresponding  degree,  the  energy  with  which  absorption  takes 
place.  They  hang  out  into  the  nutritious,  semi-fluid  mass  contained 
in  the  intestinal  cavity,  as  the  roots  of  a  tree  penetrate  the  soil;  and 
they  imbibe  the  liquefied  portions  of  the  food,  with  a  rapidity  which 
is  in  direct  proportion  to  their  extent  of  surface,  and  the  activity  of 
their  circulation. 

The  process  of  absorption  is  also  hastened  by  the  peristaltic 
movements  of  the  intestine.  The  muscular  layer  here,  as  in  other 
parts  of  the  alimentary  canal,  is  double,  consisting  of  both  circular 
and  longitudinal  fibres.  The  action  of  these  fibres  may  be  readily 
seen  by  pinching  the  exposed  intestine  with  the  blades  of  a  forceps. 
A  contraction  then  takes  place  at  the  spot  irritated,  by  which  the 
intestine  is  reduced  in  diameter,  its  cavity  obliterated,  and  its  con- 
tents forced  onward  into  the  succeeding  portion  of  the  alimentary 
canal.  The  local  contraction  then  propagates  itself  to  the  neighbor- 
ing parts,  while  the  portion  originally  contracted  becomes  relaxed ; 
so  that  a  slow,  continuous,  creeping  motion  of  the  intestine  is  pro- 
duced, by  successive  waves  of  contraction  and  relaxation,  which 
follow  each  other  from  above  downward.  At  the  same  time,  the 
longitudinal  fibres  have  a  similar  alternating  action,  drawing  the 
narrowed  portions  of  intestine  up  and  down,  as  they  successively 
enter  into  contraction,  or  become  relaxed  in  the  intervals.  The  effect 
of  the  whole  is  to  produce  a  peculiar,  writhing,  worm-like,  or 
"vermicular"  motion,  among  the  different  coils  of  intestine.  During 
life,  the  vermicular  or  peristaltic  motion  of  the  intestine  is  excited 
by  the  presence  of  food  undergoing  digestion.  By  its  action,  the 
substances  which  pass  from  the  stomach  into  the  intestine  are 
steadily  carried  from  above  downward,  so  as  to  traverse  the  entire 
length  of  the  small  intestine,  and  to  come  in  contact  successively 
with  the  whole  extent  of  its  mucous  membrane.  During  this  pas- 
sage, the  absorption  of  the  digested  food  is  constantly  going  on. 
Its  liquefied  portions  are  taken  up  by  the  villi  of  the  mucous  mem- 
brane, and  successively  disappear;  so  that,  at  the  termination  of  the 
small  intestine,  there  remains  only  the  undigestible  portion  of  the 


ABSORPTION. 


131 


food,  together,  with  the  refuse  of  the  intestinal  secretions.  These 
pass  through  the  ileo-ca?cal  orifice  into  the  large  intestine,  and  there 
become  reduced  to  the  condition  of  feces. 

The  absorption  of  the  digested  fluids  is  accomplished  both  by 
the  bloodvessels  and  the  lacteals.  It  was  formerly  supposed  that 
the  lacteals  were  the  only  agents  in  this  process;  but  it  has  now 
been  long  known  that  this  opinion  was  erroneous,  and  that  the 
bloodvessels  take  at  least  an  equal  part  in  absorption,  and  are  in 
some  respects  the  most  active  and  important  agents  of  the  two. 
Abundant  experiments  have  demonstrated  not  only  that  soluble 
substances  introduced  into  the  intestine  may  be  soon  afterward 
detected  in  tlie  blood  of  the  portal  vein,  but  that  absorption  takes 
place  more  rapidly  and  abundantly  by  the  bloodvessels  than  it  does 
by  the  lacteals.  The  most  decisive  of  these  experiments  were 
those  performed  by  Panizza  on  the  abdominal  circulation.'  This 
observer  opened  the  abdomen  of  a  horse  and  drew  out  a  fold  of 
the  small  intestine,  eight  or  nine  inches  in  length  (Fig.  40,  a,  a), 

¥m.  40. 


P  A>-izz  a"s  ExPEK  IME  XT. — art.  Intestine,     b.  Point  of  ligature  of  iiie.«Rnteric  vein,     n    Opening 
in  intestine  for  introduction  of  poison,     d.  Opening  in  mesenteric  vein  behind  the  ligature. 

which  he  included  between  two  ligatures.  A  ligature  was  then 
placed  (at  b)  upon  the  mesenteric  vein  receiving  the  blood  from 
this  portion  of  intestine;  and,  in  order  that  the  circulation  might 
not  be  interrupted,  an  opening  was  made  (at  d)  in  the  vein  behind 


'  In  Matteucci's  Lectures  on  the  Physical  Phenomena  of  Living  Beings,  Pereira's 
edition,  p.  83. 


132  ABSORPTION. 

the  ligature,  so  that  the  blood  brought  by  the  mesenteric  artery, 
after  circulating  in  the  intestinal  capillaries,  passed  out  at  the 
opening,  and  was  collected  in  a  vessel  for  examination.  Hydro- 
cyanic acid  was  then  introduced  into  the  intestine  by  an  opening  at 
c,  and  almost  immediately  afterward  its  presence  was  detected  in 
the  venous  blood  flowing  from  the  orifice  at  d.  The  animal,  how- 
ever, was  not  poisoned,  since  the  acid  was  prevented  from  gaining 
an  entrance  into  the  general  circulation  by  the  ligature  at  h. 

Panizza    afterward   varied    this   experiment    in    the    following 
manner:    Instead  of  tying  the  mesenteric  vein,  he  simply  com- 
pressed  it.     Then,  hydrocyanic   acid   being   introduced   into   the 
intestine  as  above,  no  effect  was  produced  on  the  animal,  so  long 
as  compression  was  maintained  upon  the  vein.     But  as  soon  as  the 
blood  was  allowed  to  pass  again  through  the  vessels,  symptoms  of 
general  poisoning  at  once  became  manifest.     Lastly,  in  a  third 
experiment,  the  same  observer  removed  all  the  nerves  and  lacteal 
vessels  supplying  the  intestinal  fold,  leaving  the  bloodvessels  alone 
untouched.    Hydrocyanic  acid  now  being  introduced  into  the  intes- 
tine, found  an  entrance  at  once  into  the  general  circulation,  and  the 
animal  was  immediately  poisoned      The  bloodvessels,  therefore,  are 
not  only  capable  of  absorbing  fluids  from  the  intestine,  but  may 
even  take  them  up  more  rapidly  and  abundantly  than  the  lacteals. 
These  two  sets  of  vessels,  however,  do  not  absorb  all  the  alimen- 
tary matters  indiscriminately.     It  is  one  of  the  most  important  of 
the  facts  which  have  been  established  by  modern  researches  on 
digestion  that  tbe  different  substances,  produced  by  the  operation  of 
the  digestive  fluids  on  the  food,  pass  into  the  circulation  by  different 
routes.   The  fatty  matters  are  taken  up  by  the  lacteals  under  the  form 
of  chyle,  while  the  saccharine  and  albuminous  matters  pass  by  ab- 
sorption into  the  portal  vein.    Accordingly,  after  the  digestion  of  a 
meal  containing  starchy  and  animal  matters  mixed,  albuminose  and 
sugar  are  botb  found  in  the  blood  of  the  portal  vein,  while  they  can- 
not be  detected,  in  any  large  quantity,  in  the  contents  of  the  lacteals. 
These  substances,  bowever,  do  not  mingle  at  once  with  the  general 
mass  of  the  circulation,  but  owing  to  the  anatomical  distribution  of 
the  portal  vein,  pass  first  through  the  capillary  circulation  of  the 
liver.     Soon  after  being  introduced  into  the  blood,  and  coming  in 
contact  with  its  organic  ingredients,  they  become  altered  and  con- 
verted, by  catalytic  transformation,  into   other  substances.     The 
albuminose  passes  into  the  condition   of  ordinary  albumen,  and 
probably  also  partly  into  that  of  fibrin ;  while  the  sugar  rapidly 


ABSORPTION, 


133 


Fig.  41. 


becomes  decomposed,  and  loses  its  characteristic  properties;  so 
that,  on  arriving  at  the  entrance  of  the  general  circulation,  both 
these  newly  absorbed  ingredients  have  become  already  assimilated 
to  those  which  previously  existed  in  the  blood. 

The  chyle  in  the  intestine  consists,  as  we  have  already  mentioned, 
of  oily  matters  which  have  not  been  chemically  altered,  but  simply 
reduced  to  a  state  of  emulsion.  In  chyle  drawn  from  the  lacteals 
or  the  thoracic  duct  (Fig.  41),  it  still  presents  itself  in  the  same 
condition  and  retains  all  the 
chemical  properties  of  oil. 
Examined  by  the  microscope, 
it  is  seen  to  exist  under  the 
form  of  fine  granules  and 
molecules,  which  present  the 
ordinary  appearances  of  oil 
in  a  state  of  minute  subdivi- 
sion. The  chyle,  therefore, 
does  not  represent  the  entire 
product  of  the  digestive  pro- 
cess, but  contains  only  the 
fatty  substances,  suspended 
by  emulsion  in  a  serous  fluid. 

During  the  time  that  intes- 
tinal absorption  is  going  on, 
after  a  meal  containing  fatty 

ingredients,  the  lacteals  may  be  seen  as  white,  opaque  vessels,  dis- 
tended with  milky  chyle,  passing  through  the  mesentery,  and  con- 
verging from  its  intestinal  border  toward  the  receptaculum  chyli, 
near  the  spinal  column.  During  their  course,  they  pass  through 
several  successive  rows  of  mesenteric  glands,  which  also  become 
turgid  with  chyle,  while  the  process  of  digestion  is  going  on.  The 
lacteals  then  conduct  the  chyle  to  the  receptaculum  chyli,  whence 
it  passes  upward  through  the  thoracic  duct,  and  is  finally  dis- 
charged, at  the  termination  of  this  canal,  into  the  left  subclavian 
vein.  (Fig.  42.)  It  is  then  mingled  with  the  returning  current  of 
venous  blood,  and  passes  into  the  right  cavities  of  the  heart. 

The  lacteals,  however,  are  not  a  special  system  of  vessels  by  them- 
selves, but  are  simply  a  part  of  the  great  system  of  "  absorbent"  or 
"  lymphatic"  vessels,  which  are  to  be  found  everywhere  in  the  integu- 
ments of  the  head,  the  parietes  of  the  trunk,  the  upper  and  lower 
extremities,  and  in  the  muscular  tissues  and  mucous  membranes 


Chyle  from  c  o  m  m  e  x  c  e  .m  e  x  t  o  f  Thoracic 
PtJCT,  from  the  Dog. — The  molecules  viiiy  iu  size 
from  1-1 0,000th  of  au  inch  dowu-ward. 


134 


ABSORPTION. 


throughout  the  body.     The  walls  of  these  vessels  are  thinner  and 
more  transparent  than  those  of  the  arteries  and  veins,  and  they 

'are  consequently  less  easily  de- 
tected by  ordinary  dissection. 
They  originate  in  the  tissues  of 
the  above-mentioned  parts  by 
an  irregular  plexus.  They 
pass  from  the  extremities  to- 
ward the  trunk,  converging  and 
uniting  with  each  other  like  the 
veins,  their  principal  branches 
taking  usually  the  same  direc- 
tion with  the  nerves  and  blood- 
vessels, and  passing,  at  various 
points  in  their  course,  through 
certain  glandular  bodies,  the 
"lymphatic"  or  "absorbent" 
glands.  The  lymphatic  glands, 
among  which  are  included  the 
mesenteric  glands,  consist  of  an 
external  layer  of  fibrous  tissue 
and  a  contained  pulp  or  paren- 
chyma. The  investing  layer 
of  fibrous  tissue  sends  off  thin 
septa  or  laminae  from  its  inter- 
nal surface,  which  penetrate 
the  substance  of  the  gland  in 
every  direction  and  unite  with 
each  other  at  various  points. 
In  this  way  they  form  an  interlacing  laminated  framework,  which 
divides  the  substance  of  the  gland  into  numerous  roianded  spaces 
or  alveoli.  These  alveoli  are  not  completely  isolated,  but  communi- 
cate with  each  other  by  narrow  openings,  where  the  intervening 
septa  are  incomplete.  These  cavities  are  filled  with  a  soft,  reddish 
pulp,  which  is  penetrated,  according  to  Kolliker,  like  the  solitary 
and  agminated  glands  of  the  intestine,  by  a  fine  network  of  capil- 
lary bloodvessels.  The  solitary  and  agminated  glands  of  the 
intestine  are,  therefore,  closely  analogous  in  their  structure  to  the 
lymphatics.  The  former  are  to  be  regarded  as  simple,  the  latter  as 
compound  vascular  glands. 

The  arrangement  of  the  lymphatic  vessels  in  the  interior  of  the 


Lacteals,  Thoracic  Duct,  &c. — a.  Intes- 
tine, h.  Vena  cava  inferior,  c,  c.  Kight  and  left 
subclavian  veins,  d.  Point  of  opening  of  thoracic 
duct  into  left  subclavian. 


ABSOEPTION.  135 

glands  is  not  precisely  understood.  Each  lymphatic  vessel,  as  it 
enters  the  gland,  breaks  up  into  a  number  of  minute  ramifications, 
the  vasa  afferentia ;  and  other  similar  twigs,  forming  the  vasa  effer- 
entia^  pass  off  in  the  opposite  direction,  from  the  further  side  of  the 
gland  ;  but  the  exact  mode  of  communication  between  the  two  has 
not  been  definitely  ascertained.  All  the  fluids,  however,  arriving 
by  the  vasa  afferentia,  must  pass  in  some  way  through  the  tissue  of 
the  gland,  before  they  are  carried  away  again  by  the  vasa  efferentia. 
From  the  lower  extremities  the  lymphatic  vessels  enter  the  abdomen 
at  the  groin  and  converge  toward  the  receptaculum  chyli,  into 
which  their  fluid  is  discharged,  and  afterward  conveyed,  by  the 
thoracic  duct,  to  the  left  subclavian  vein. 

The  fluid  which  these  vessels  contain  is  called  the  lymph.  It  is 
a  colorless  or  slightly  yellowish  transparent  fluid,  which  is  absorbed 
by  the  lymphatic  vessels  from  the  tissues  in  which  they  originate. 
But  little  is  known  regarding  its  composition,  except  that  it  con- 
tains, beside  water  and  saline  matters,  a  small  quantity  of  fibrin 
and  albumen.  Its  ingredients  are  evidently  derived  from  the  meta- 
morphosis of  the  tissues,  and  are  returned  to  the  centre  of  the 
circulation  in  order  to  be  eliminated  by  excretion,  or  in  order  to 
undergo  some  new  transforming  or  renovating  process.  We  are 
ignorant,  however,  with  regard  to  the  precise  nature  of  their  charac- 
ter and  destination. 

The  lacteals  are  simply  that  portion  of  the  absorbents  which 
originate  in  the  mucous  membrane  of  the  small  intestine.  During 
the  intervals  of  digestion,  these  vessels  contain  a  colorless  and 
transparent  lymph,  entirely  similar  to  that  which  is  found  in  other 
parts  of  the  absorbent  system.  After  a  meal  containing  only 
starchy  or  albuminoid  substances,  there  is  no  apparent  change  in 
the  character  of  their  contents.  But  after  a  meal  containing  fatty 
matters,  these  substances  are  taken  up  by  the  absorbents  of  the 
intestine,  which  then  become  filled  with  the  white  chylous  emul- 
sion, and  assume  the  appearance  of  lacteals,  (Fig.  48.)  It  is  for 
this  reason  that  lacteal  vessels  do  not  show  themselves  upon  the 
stomach  nor  upon  the  first  few  inches  of  the  duodenum ;  because 
oleaginous  matters,  as  we  have  seen,  are  not  digested  in  the  stomach, 
but  only  after  they  have  entered  the  intestine  and  passed  the  orifice 
of  the  pancreatic  duct. 

The  presence  of  chyle  in  the  lacteals  is,  therefore,  not  a  con- 
stant, but  only  a  periodical  phenomenon.  The  fatty  substances 
constituting  the  chyle  begin  to  be  absorbed  during  the  process  of 


136 


ABSORPTION. 


digestion,  as  soon  as  they  have  been  disintegrated  and  emulsioned 
by  the  action  of  the  intestinal  fluids.  As  digestion  proceeds,  they 
accumulate  in  larger  quantity,  and  gradually  fill  the  whole  lacteal 

Fig.  43. 


LACTEALS    AXD    Lr-MPHATICS. 


system  and  the  thoracic  duct.  As  they  are  discharged  into  the 
subclavian  vein,  and  mingled  with  the  blood,  they  can  still  be  dis- 
tinguished in  the  circulating  fluid,  as  a  mixture  of  oily  molecules 
and  granules,  between  the  orifice  of  the  thoracic  duct  and  the  right 
side  of  the  heart.     While  passing  through  the  pulmonary  circula- 


ABSORPTIOlSr.  137 

tion,  however,  they  disappear.  Precisely  what  becomes  of  them, 
or  what  particular  chemical  changes  they  undergo,  is  not  certainly 
known.  They  are,  at  all  events,  so  altered  in  the  blood,  while 
passing  through  the  lungs,  that  they  lose  the  form  of  a  fatty  emul- 
sion, and  are  no  longer  to  be  recognized  by  the  usual  tests  for 
oleaginous  substances. 

The  absorption  of  fat  from  the  intestine  is  not,  however,  exclu- 
sively performed  by  the  lacteals.  Some  of  it  is  also  taken  up, 
under  the  same  form,  by  the  bloodvessels.  It  has  been  ascertained 
by  the  experiments  of  Bernard'  that  the  blood  of  the  mesenteric 
veins,  in  the  carnivorous  animals,  contains,  during  intestinal  diges- 
tion, a  considerable  amount  of  fatty  matter  in  a  state  of  minute 
subdivision.  Other  observers,  also  (Lehmann,  Schultz,  Simon),  have 
found  the  blood  of  the  portal  vein  to  be  considerably  richer  in  fat 
than  that  of  other  veins,  particularly  while  intestinal  digestion  is 
going  on  with  activity.  In  birds,  reptiles,  and  fish,  furthermore, 
according  to  Bernard,  the  intestinal  lymphatics  are  never  filled 
with  opaque  chyle,  but  only  with  a  transparent  lymph;  so  that  these 
animals  may  be  said  to  be  destitute  of  lacteals,  and  in  them  the  fatty 
substances,  like  other  alimentary  materials,  are  taken  up  altogether 
by  the  bloodvessels.  In  quadrupeds,  on  the  other  hand,  and  in 
the  human  subject,  the  absorption  of  fat  is  accomplished  both  by 
the  bloodvessels  and  the  lacteals.  A  certain  portion  is  taken  up 
by  the  former,  while  the  superabundance  of  the  fatty  emulsion  is 
absorbed  by  the  latter. 

A  difficulty  has  long  been  experienced  in  accounting  for  the  absorp- 
tion of  fat  from  the  intestine,  owing  to  its  being  considered  as  a  non- 
endosmotic  substance;  that  is,  as  incapable,  in  its  free  or  undissolved 
condition,  of  penetrating  and  passing  through  an  animal  membrane 
by  endosmosis.  It  is  stated,  indeed,  that  if  a  fine  oily  emulsion  be 
placed  on  one  side  of  an  animal  membrane  in  an  endosmometer, 
and  pure  water  on  the  other,  the  water  will  readily  penetrate  the 
substance  of  the  membrane,  while  the  oily  particles  cannot  be  made 
to  pass,  even  under  a  high  pressure.  Though  this  be  true,  how- 
ever, for  pure  water,  it  is  not  true  for  slightly  alkaline  fluids,  like 
the  serum  of  the  blood  and  the  lymph.  This  has  been  demon- 
strated by  the  experiments  af  Matteucci,  in  which  he  made  an 
emulsion  with  an  alkaline  fluid  containing  43  parts  per  thou- 
sand of  caustic  potass.    Such  a  solution  has  no  perceptible  alkaline 

'  Lemons  de  Physiologic  Experiinentale.     Paris,  1'56,  p.  325. 


138 


ABSORPTION. 


taste,  and  its  action  on  reddened  litmus  paper  is  about  equal  to 
that  of  the  lymph  and  chyle.  If  this  emulsion  were  placed  in  an 
endosmometer,  together  with  a  watery  alkaline  solution  of  similar 
strength,  it  was  found  that  the  oily  particles  penetrated  through  the 
animal  membrane  without  much  difficulty,  and  mingled  with  the  fluid 
on  the  opposite  side.  Although,  therefore,  we  cannot  explain  the 
exact  mechanism  of  absorption  in  the  case  of  fat,  still  we  know 

that  it  is  not  in  opposition  to 
^^'     *  the   ordinary  phenomena  of 

endosmosis;  for  endosmosis 
will  take  place  with  a  fatty 
emulsion,  provided  the  fluids 
used  in  the  experiment  be 
slightly  alkaline  in  reaction. 
It  is,  accordingly,  by  a  pro- 
cess of  endosmosis,  or  imbi- 
bition, that  the  villi  take  up 
the  digested  fatty  substances. 
There  are  no  open  orifices 
or  canals,  into  which  the  oil 
penetrates;  but  it  passes  di- 
rectly into  and  through  the 
substance  of  the  villi.  The 
epithelial  cells  covering  the  external  surface  of  the  villus  are  the  first 
active  agents  in  this  absorption.     In  the  intervals  of  digestion  (Fig. 

44)  these  cells  are  but  slightly 


Intestinal  Epithelium;  from  the  Dog,  -while 
fasting. 


Fig.  45. 


Intestinal  Epithelium;  from  the  Dog,  dur- 
ing the  digestion  of  fat. 


granular  and  nearly  trans- 
parent in  appearance.  But  if 
examined  during  the  diges- 
tion and  absorption  of  fat 
(Fig,  45),  their  substance  is 
seen  to  be  crowded  with  oily 
particles,  which  they  have 
taken  up  from  the  intestinal 
cavity  by  absorption.  The 
oily  matter  then  passes  on- 
ward, penetrating  deeper  and 
deeper  into  the  substance  of 
the  villus,  until  it  is  at  last 
received  by  the  capillary  ves- 
sels and  lacteals  in  its  centre. 


ABSOEPTION.  139 

The  fatty  substances  taken  up  by  the  portal  vein,  like  those  ab- 
sorbed by  the  lacteals,  do  not  at  once  enter  the  general  circulation, 
but  pass  first  through  the  capillary  system  of  the  liver.  Thence 
they  are  carried,  with  the  blood  of  the  hepatic  vein,  to  the  right 
side  of  the  heart,  and  subsequently  through  the  capillary  system  of 
the  lungs.  During  this  passage  they  become  altered  in  character, 
as  above  described,  and  lose  for  the  most  part  the  distinguishing 
characteristics  of  oily  matter,  before  they  have  passed  beyond  the 
pulmonary  circulation. 

But  as  digestion  proceeds,  an  increasing  quantity  of  fatty  matter 
finds  its  way,  by  these  two  passages,  into  the  blood;  and  a  time  at 
last  arrives  when  the  whole  of  the  fat  so  introduced  is  not  destroyed 
during  its  passage  through  the  lungs.  Its  absorption  taking  place 
at  this  time  more  rapidly  than  its  decomposition,  it  begins  to  ap- 
pear,, in  moderate  quantity,  in  the  blood  of  the  general  circulation ; 
and,  lastly,  when  the  intestinal  absorption  is  at  its  point  of  greatest 
activity,  it  is  found  in  considerable  abundance  throughout  the 
entire  vascular  system.  At  this  period,  some  hours  after  the  inges- 
tion of  food  rich  in  oleaginous  matters,  the  blood  of  the  general 
circulation  everywhere  contains  a  superabundance  of  fat,  derived 
from  the  digestive  process.  If  blood  be  then  drawn  from  the 
veins  or  arteries  in  any  part  of  the  body,  it  will  present  the  pecu- 
liar appearance  known  as  that  of  "  chylous"  or  "  milky"  blood. 
After  the  separation  of  the  clot,  the  serum  presents  a  turbid  ap- 
pearance; and  the  fatty  substances,  which  it  contains,  rise  to  the 
top  after  a  few  hours,  and  cover  its  surface  with  a  partially  opaque 
and  creamy-looking  pellicle.  This  appearance  has  been  occasion- 
ally observed  in  the  human  subject,  particularly  in  bleeding  for 
apoplectic  attacks  occurring  after  a  full  meal,  and  has  been  mis- 
taken, in  some  instances,  for  a  morbid  phenomenon.  It  is,  however, 
a  perfectly  natural  one,  and  depends  simply  on  the  rapid  absorp- 
tion, at  certain  periods  of  digestion,  of  oleaginous  substances  from 
the  intestine.  It  can  be  produced  at  will,  at  any  time,  in  the  dog, 
by  feeding  him  with  fat  meat,  and  drawing  blood,  seven  or  eight 
hours  afterward,  from  the  carotid  artery  or  the  jugular  vein. 

This  state  of  things  continues  for  a  varying  length  of  time, 
according  to  the  amount  of  oleaginous  matters  contained  in  the 
food.  When  digestion  is  terminated,  and  the  fat  ceases  to  be  intro- 
duced in  unusual  quantity  into  the  circulation,  its  transformation 
and  decomposition  continuing  to  take  place  in  the  blood,  it  dis- 
appears gradually  from  the  veins,  arteries,  and  capillaries  of  the 


140  ABSORPTION. 

general  system;  and,  finally,  when  the  whole  of  the  fat  has  been 
disposed  of  by  the  nutritive  processes,  the  serum  again  becomes 
transparent,  and  the  blood  returns  to  its  ordinary  condition. 

In  this  manner  the  nutritive  elements  of  the  food,  prepared  for 
absorption  by  the  digestive  process,  are  taken  up  into  the  circulation 
under  the  different  forms  of  albuminose,  sugar,  and  chyle,  and  accu- 
mulate as  such,  at  certain  times,  in  the  blood.  But  these  conditions 
are  only  temporary,  or  transitional.  The  nutritive  materials  soon 
pass,  by  catalytic  transformation,  into  other  forms,  and  become 
assimilated  to  the  pre-existing  elements  of  the  circulating  fluid. 
They  thus  accomplish  finally  the  whole  object  of  digestion  ;  which 
is  to  replenish  the  blood  by  a  supply  of  new  materials  from  without. 
There  are,  however,  two  other  intermediate  processes,  taking  place 
partly  in  the  liver  and  partly  in  the  intestine,  at  about  the  same 
time,  and  having  for  their  object  the  final  preparation  and  perfec- 
tion of  the  circulating  fluid.  These  two  processes  require  to  be 
studied,  before  we  can  pass  on  to  the  particular  description  of  the 
blood  itself.  They  are :  1st,  the  secretion  and  reabsorption  of  the 
bile ;  and  2d,  the  production  of  sugar  in  the  liver,  and  its  subse- 
quent decomposition  in  the  blood. 


THE    BILE.  141 


CHAPTER   VIII. 

THE   BILE. 

The  bile  is  more  easily  obtained  in  a  state  of  purity  than  any 
other  of  the  secretions  which  find  their  way  into  the  intestinal 
canal,  owing  to  the  existence  of  a  gall-bladder  in  which  it  accu- 
mulates, and  from  which  it  may  be  readily  obtained  without  any 
other  admixture  than  the  mucus  of  the  gall-bladder  itself.  Not- 
withstanding this,  its  study  has  proved  an  unusually  difficult  one. 
This  difficulty  has  resulted  from  the  peculiar  nature  of  the  biliary 
ingredients,  and  the  readiness  with  which  they  become  altered  by 
chemical  manipulation;  and  it  is,  accordingly,  only  quite  recently 
that  we  have  arrived  at  a  correct  idea  of  its  real  constitution. 

The  bile,  as  it  comes  from  the  gall-bladder,  is  a  somewhat  viscid 
and  glutinous  fluid,  varying  in  color  and  specific  gravity  according 
to  the  species  of  animal  from  which  it  is  obtained.  Human  bile  is 
of  a  dark  golden  brown  color,  ox  bile  of  a  greenish  yellow,  pig's 
bile  of  a  nearly  clear  yellow,  and  dog's  bile  of  a  deep  brown.  We 
have  found  the  specific  gravity  of  human  bile  to  be  1018,  that  of 
ox  bile  1024,  that  of  pig's  bile  1030  to  1036.  The  reaction  of  the 
bile  with  test-paper  cannot  easily  be  determined ;  since  it  has  only 
a  bleaching  or  decolorizing  effect  on  litmus,  and  does  not  turn  it 
either  blue  or  red.  It  is  probably  either  neutral  or  very  slightly 
alkaline.  A  very  characteristic  physical  property  of  the  bile  is 
that  of  frothing  up  into  a  soap-like  foam  when  shaken  in  a  test- 
tube,  or  when  air  is  forcibly  blown  into  it  through  a  small  glass 
tube  or  blowpipe.  The  bubbles  of  foam,  thus  produced,  remain 
for  a  long  time  without  breaking,  and  adhere  closely  to  each  other 
and  to  the  sides  of  the  glass  vessel. 

The  following  is  an  analysis  of  the  bile  of  the  ox,  based  on  the 
calculations  of  Berzelius,  Frerichs,  and  Lehmann  : — 


142  THE    BILE. 

Composition  of  Ox  Bile. 

Water 880.00 

Gljko-cholate  of  soda  ........       \ 

Tauro-cholate  "      " }      ^^'^^ 

Biliverdine    ..........") 

Fats 

Oleates,  margarates,  and  stearates  of  soda  and  potass    . 
Cholesterin    ......... 

Chloride  of  sodium         ........       ^ 

Phosphate  of  soda         ....... 

"  "   lime 

"  "   magnesia  ...... 

Carbonates  of  soda  and  potass       .         .         .    •     .         . 

Mucus  of  the  gall-bladder     .         .         .         .         .         .         .         .1.34 


1-     13.42 


15.24 


1000.00 

Biliverdine. — Of  the  above  mentioned  ingredients,  hiliverdine 
is  peculiar  to  the  bile,  and  therefore  important,  though  not  pre- 
sent in  large  quantity.  This  is  the  coloring  matter  of  the  bile. 
It  is,  like  the  other  coloring  matters,  an  uncrystallizable  organic 
substance,  containing  nitrogen,  and  yielding  to  ultimate  analysis  a 
small  quantity  of  iron.  It  exists  in  such  small  quantity  in  the  bile 
that  its  exact  proportion  has  never  been  determined.  It  is  formed, 
so  far  as  can  be  ascertained,  in  the  substance  of  the  liver,  and  does 
not  pre-exist  in  the  blood.  It  may,  however,  be  reabsorbed  in 
cases  of  biliary  obstruction,  when  it  circulates  with  the  blood  and 
stains  nearly  all  the  tissues  and  fluids  of  the  body,  of  a  peculiar 
lemon  yellow  color.  This  is  the  symptom  which  is  characteristic 
of  jaundice. 

Cholesterin  (CjjHgjO). — This  is  a  crystallizable  substance  which 
resembles  the  fats  in  many  respects ;  since  it  is  destitute  of  nitrogen, 
readily  inflammable,  soluble  in  alcohol  and  ether,  and  entirely  in- 
soluble in  water.  It  is  not  saponifiable,  however,  by  contact  with 
the  alkalies,  and  is  distinguished  on  this  account  from  the  ordinary 
fatty  substances.  It  occurs,  in  a  crystalline  form,  mixed  with  color- 
ing matter,  as  an  abundant  ingredient  in  most  biliary  calculi ;  and 
is  found  also  in  different  regions  of  the  body,  forming  a  part  of 
various  morbid  deposits.  We  have  met  with  it  in  the  fluid  of 
hydrocele,  and  in  the  interior  of  many  encysted  tumors.  The 
crystals  of  cholesterin  (Fig.  46)  have  the  form  of  very  thin,  color- 
less, transparent,  rhomboidal  plates,  portions  of  which  are  often 
cut  out  by  lines  of  cleavage  parallel  to  the  sides  of  the  crystal. 
They  frequently  occur  deposited  in  layers,  in  which  the  outlines  of 


THE    BILE. 


143 


Cholesterin  is  not  formed  in  the 


Fig.  46. 


the  subjacent  crystals  show  very  distinctly  through  the  substance 

of  those  which  are  placed  above 

liver,  but  originates  in  the 

substance  of  the  brain  and 

nervous  tissue,  from  which 

it  may  be  extracted  in  large 

quantity   by   the    action   of 

alcohol.     From  these  tissues 

it  is  absorbed  by  the  blood, 

then  conveyed  to  the  liver, 

and  discharged  with  the  bile. 

The  fatty  substances  and 
inorganic  saline  ingredients 
of  the  bile  require  no  special 
description. 

C  HO  LESTER  IX  from  an  Encysted  Tumor. 

Biliary  Salts. — By  far 
the  most  important  and  characteristic  ingredients  of  this  secretion 
are  the  two  saline  substances  mentioned  above  as  the  glyko-cholate 
and  tauro-cholate  of  soda.  These  substances  were  first  discovered 
by  Strecker,  in  1848,  in  the  bile  of  the  ox.  They  are  both  freely 
soluble  in  water  and  in  alcohol,  but  insoluble  in  ether.  One  of 
them,  the  tauro-cholate,  has  the  property,  when  itself  in  solution 
in  water,  of  dissolving  a  certain  quantity  of  fat ;  and  it  is  probably 
owing  to  this  circumstance  that  some  free  fat  is  present  in  the  bile. 
The  two  biliary  substances  are  obtained  from  ox-bile  in  the  follow- 
ing manner : — 

The  bile  is  first  evaporated  to  dryness  by  the  water-bath.  The 
dry  residue  is  then  pulverized  and  treated  with  absolute  alcohol,  in 
the  proportion  of  at  least  5j  of  alcohol  to  every  five  grains  of  dry 
residue.  The  filtered  alcoholic  solution  has  a  clear  yellowish  color. 
It  contains,  beside  the  glyko-cholate  and  tauro-cholate  of  soda,  the 
coloring  matter  and  more  or  less  of  the  fats  originally  present  in 
the  bile.  On  the  addition  of  a  small  quantity  of  ether,  a  dense, 
whitish  precipitate  is  formed,  which  disappears  again  on  agitating 
and  thoroughly  mixing  the  fluids.  On  the  repeated  addition  of 
ether,  the  precipitate  again  falls  down,  and  when  the  ether  has  been 
added  in  considerable  excess,  six  to  twelve  times  the  volume  of  the 
alcoholic  solution,  the  precipitate  remains  permanent,  and  the  whole 
mixture  is  filled  with  a  dense,  whitish,  opaque  deposit,  consisting  of 


144 


THE    BILE. 


the  glyko-cholate  and  tauro-cholate  of  soda,  thrown  down  under 
the  form  of  heavy  flakes  and  granules,  part  of  which  subside  to 
the  bottom  of  the  test-tube,  while  part  remain  for  a  time  in  suspen- 
sion. Gradually  these  flakes  and  granules  unite  with  each  other 
and  fuse  together  into  clear,  brownish-yellow,  oily,  or  resinous- 
looking  drops.  At  the  bottom  of  the  test-tube,  after  two  or  three 
hours,  there  is  usually  collected  a  nearly  homogeneous  layer  of 
this  deposit,  while  the  remainder  continues  to  adhere  to  the  sides 
of  the  glass  in  small,  circular,  transparent  drops.  The  deposit  is 
semi-fluid  in  consistency,  and  sticky,  like  Canada  balsam  or  half- 
rnelted  resin ;  and  it  is  on  this  account  that  the  ingredients  compos- 
ing it  have  been  called  the  "  resinous  matters"  of  the  bile.  They 
have,  however,  no  real  chemical  relation  with  true  resinous  bodies, 
since  they  both  contain  nitrogen,  and  differ  from  resins  also  in 
other  important  particulars. 

At  the  end  of  twelve  to  twenty-four  hours,  the  glyko-cholate  of 
soda  begins  to  crystallize.  The  crystals  radiate  from  various  points 
in  the  resinous  deposit,  and  shoot  upward  into  the  supernatant 
fluid,  in  white,  silky  bundles.  (Fig,  47.)     If  some  of  these  crystals 


Fig.  47 


Fig.  48. 


Ox -BILE,  extracted  with  absolute 
alcohol  and  precipitated  with  ether. 


Gt.tko-cholate  of  Soda  from  Ox-bile, 
after  two  days'  crystallization.  At  the  lower  part  of 
the  figure  the  crystals  are  melting  into  drops,  from  the 
evaporation  of  the  ether  and  absorption  of  moisture. 


be  removed  and  examined  by  the  microscope,  they  are  found  to  be 
of  a  very  delicate  acicular  form,  running  to  a  finely  pointed 
extremity,  and  radiating,  as  already  mentioned,  from  a   central 


THE    BILE. 


145 


point.  (Fig.  48.)  As  the  ether  evaporates,  the  crystals  absorb 
moisture  from  the  air,  and  melt  up  rapidly  into  clear  resinous 
drops;  so  that  it  is  difficult  to  keep  them  under  the  microscope 
long  enough  for  a  correct  drawing  and  measurement.  The  crystal- 
lization in  the  test-tube  goes  on  after  the  first  day,  and  the  crystals 
increase  in  quantity  for  three  or  four,  or  even  five  or  six  days,  until 
the  whole  of  the  glyko-cholate  of  soda  present  has  assumed  the 
solid  form.  The  tauro-cholate,  however,  is  uncrystallizable,  and 
remains  in  an  amorphous  condition.  If  a  portion  of  the  deposit  be 
now  removed  and  examined  by  the  microscope,  it  is  seen  that  the 
crystals  of  gl3^ko-cholate  of 
soda  have  increased  conside-  ^^' 

rably  in  thickness  (Fig.  49), 
so  that  their  transverse  dia- 
meter may  be  readily  esti- 
mated. The  uncrystallizable 
tauro-cholate  appears  under 
the  form  of  circular  drops, 
varying  considerably  in  size, 
clear,  transparent,  strongly 
refractive,  and  bounded  by 
a  dark,  well-defined  outline. 
These  drops  are  not  to  he  distin- 
guished, by  any  of  their  ojyiical 
properties,  from  oil-glohides, 
as  they  usually  appear  under 
the  microscope.  They  have 
the  same  refractive  power, 
the  same  dark  outline  and  bright  centre,  and  the  same  degree  of 
consistency.  They  would  consequently  be  liable  at  all  times  to  be 
mistaken  for  oil-globules,  were  it  not  for  the  complete  dissimilarity 
of  their  chemical  properties. 

Both  the  glyko-cholate  and  tauro-cholate  of  soda  are  very  freely 
soluble  in  water.  If  the  mixture  of  alcohol  and  ether  be  poured 
ofl'  and  distilled  water  added,  the  deposit  dissolves  rapidly  and 
completely,  with  a  more  or  less  distinct  yellowish  color,  accord- 
ing to  the  proportion  of  coloring  matter  originally  present  in  the 
bile.  The  two  biliary  substances  present  in  the  watery  solution 
may  be  separated  from  each  other  by  the  following  means.  On 
tlie  addition  of  acetate  of  lead,  the  glyko-cholate  of  soda  is  decom- 
posed, and  precipitates  as  a  glyko-cholate  of  lead.  The  precipitate, 
10 


Glyko-cholate  and  Tauro-cholate  of 
Soda,  from  Os-bile,  after  six  days'  crystalliza- 
tion. The  glyko-cholate  is  crystallized ;  the  tauro- 
cliolate  is  in  fluid  drops. 


146  THE    BILE. 

separated  bj  filtration  from  the  remaining  fluid,  is  then  decomposed 
in  turn  by  carbonate  of  soda,  and  the  original  glyko-cholate  of  soda 
reproduced.  The  filtered  fluid  which  remains,  and  which  contains 
the  tauro-cholate  of  soda,  is  then  treated  with  subacetaie  of  lead, 
which  precipitates  a  tauro-cholate  of  lead.  This  is  separated  by 
filtration,  washed,  and  decomposed  again  by  carbonate  of  soda,  as 
in  the  former  case. 

The  two  biliary  substances  in  ox  bile  may,  therefore,  be  dis- 
tinguished by  their-  reactions  with  the  salts  of  lead.  Both  are 
precipitable  by  the  subacetate;  but  the  glyko-cholate  of  soda  is 
precipitable  also  by  the  acetate,  while  the  tauro-cholate  is  not  so. 
If  subacetate  of  lead,  therefore,  be  added  to  the  mixed  watery  solu- 
tion of  the  two  substances,  and  the  whole  filtered,  the  subsequent 
addition  of  acetate  of  lead  to  the  filtered  fluid  will  produce  no  pre- 
cipitate, because  both  the  biliary  matters  have  been  entirely  thrown 
down  with  the  deposit;  but  if  the  acetate  of  lead  be  first  added,  it 
will  precipitate  the  glyko-cholate  alone,  and  the  tauro-cholate  may 
afterward  be  thrown  down  separately  by  the  subacetate. 

These  two  substances,  examined  separately,  have  been  found  to 
possess  the  following  properties : — 

Glylw-cholate  of  soda  (^diOfi^^^^O^^  crystallizes,  when  precipi- 
tated by  ether  from  its  alcoholic  solution,  in  radiating  bundles  of 
fine  white  silky  needles,  as  above  described.  It  is  composed  of 
soda,  united  with  a  peculiar  acid  of  organic  origin,  viz.,  glyko-cholic 
acid  (C52li42-^0,i,HO).  This  acid  is  crystallizable  and  contains  nitro- 
gen, as  shown  by  the  above  formula,  which  is  that  given  by  Leh- 
man n.  If  boiled  for  a  long  time  with  a  dilute  solution  of  potass, 
glyko-cholic  acid  is  decomposed  with  the  production  of  two  new 
substances;  the  first  a  non-nitrogenous  acid  body,  cholic  acid 
(C48H3g09,IIO) ;  the  second  a  nitrogenous  neutral  body,  glycine 
(C4H5NOJ.  Hence  the  name,  glyko-cholic  acid,  given  to  the 
original  substance,  as  if  it  were  a  combination  of  cholic  acid  with 
glycine.  In  reality,  however,  these  two  substances  do  not  exist 
originally  in  the  glyko-cholic  acid,  but  are  rather  new  combinations 
of  its  elements,  produced  by  long  boiling,  in  contact  with  potass 
and  water.  They  are  not,  therefore,  to  be  regarded  as,  in  any  way, 
natural  ingredients  of  the  bile,  and  do  not  throw  any  light  on  the 
real  constitution  of  glyko-cholic  acid. 

Tauro-cholate  of  soda  (^diO^G^^^^^^O^^  is  also  a  very  abundant 
ingredient  of  the  bile.     It  is  said  by  Robin  and  YerdeiP  that  it  is 

'  Chimie  Anatomique  et  Physiologique,  vol.  ii.  p.  473. 


THE    BILE.  147 

not  crystallizable,  owing  probably  to  its  not  having  been  separated 
as  yet  in  a  perfectly  pure  condition.  Lehmann  states,  on  the  con- 
trary, that  it  may  crystallize,'  when  kept  for  a  long  time  in  contact 
with  ether.  We  have  not  been  able  to  obtain  this  substance,  how- 
ever, in  a  crystalline  form.  Its  acid  constituent,  tauro-cliolic  acid^ 
is  a  nitrogenous  body,  like  glyko-cholic  acid,  but  differs  from  the 
latter  by  containing  in  addition  two  equivalents  of  sulphur.  By 
long  boiling  in  a  dilute  solution  of  potass,  it  is  decomposed  with 
the  production  of  two  other  substances;  the  first  of  them  the  same 
acid  body  mentioned  above  as  derived  from  the  glyko-cholic,  viz., 
cholic  acid;  and  the  second  a  new  nitrogenous  neutral  body,  viz., 
taurine  {Q^^'^'^f)^.  The  same  remark  holds  good  with  regard  to 
these  two  bodies,  that  we  have  already  made  in  respect  to  the  sup- 
posed constituents  of  glyko-cholic  acid.  Neither  cholic  acid  nor 
taurine  can  be  properly  regarded  as  really  ingredients  of  tauro- 
cholic  acid,  but  only  as  artificial  products  resulting  from  its  altera- 
tion and  decomposition. 

The  glyko-cholates  and  tauro-cholates  are  formed,  so  far  as  we 
know,  exclusively  in  the  liver;  since  they  have  not  been  found  in 
the  blood,  nor  in  any  other  part  of  the  body,  in  healthy  animals; 
nor  even,  in  the  experiments  of  Kunde,  Moleschott,  and  Lehmann 
on  frogs,^  after  the  entire  extirpation  of  the  liver,  and  consequent 
suppression  of  the  bile.  These  substances  are,  therefore,  produced 
in  the  glandular  cells  of  the  liver,  by  transformation  of  some  other 
of  their  ingredients.  They  are  then  exuded  in  a  soluble  form,  as 
part  of  the  bile,  and  finally  discharged  by  the  excretory  hepatic 
ducts. 

The  two  substances  described  above  as  the  tauro-cholate  and 
glyko-cholate  of  soda  exist,  properly  speaking,  only  in  the  bile  of 
the  ox,  where  they  were  first  discovered  by  Strecker.  In  examin- 
ing the  biliary  secretions  of  different  species  of  animals,  Strecker 
found  so  great  a  resemblance  between  them,  that  he  was  disposed 
to  regard  their  ingredients  as  essentially  the  same.  Having  estab- 
lished the  existence  in  ox  bile  of  two  peculiar  substances,  one 
crystallizable  and  non-sulphurous  (glyko-cholate),  the  other  uncrys- 
tallizable  and  sulphurous  (tauro-cholate),  he  was  led  to  consider 
the  bile  in' all  species  of  animals  as  containing  the  same  substances, 
and  as  differing  only  in  the  relative  quantity  in  which  the  two 

'  Physiological  Chemistry,  Phil,  ed.,  vol.  i.  p.  209. 

2  Lehmann's  Physiological  Chemistry,  Phil,  ed.,  vol.  i.  p.  476. 


148 


THE    BILE. 


Fig.  50. 


were  present.  The  only  exception  to  this  was  supposed  to  be  pig's 
bile,  in  which  Strecker  found  a  peculiar  organic  acid,  the  "  hyo- 
cbolic"  or  "  hjo-cholinic"  acid,  in  combination  with  soda  as  a  base. 
The  above  conclusion  of  his,  however,  was  not  entirely  correct. 
It  is  true  that  the  bile  of  all  animals,  so  far  as  examined,  contains 
peculiar  substances,  which  resemble  each  other  in  being  freely 
soluble  in  water,  soluble  in  absolute  alcohol,  and  insoluble  in  ether; 
and  in  giving  also  a  peculiar  reaction  with  Pettenkofer's  test,  to  be 
described  presently.  But,  at  the  same  time,  these  substances  pre- 
sent certain  minor  differences  in  different  animals,  which  show  them 
not  to  be  identical. 

In  dog's  bile,  for  example,  there  are,  as  in  ox  bile,  two  substances 
precipitable  by  ether  from  their  alcoholic  solution;  one  crystalliz- 
able,  the  other  not  so.  But  the  former  of  these  substances  crystallizes 
much  more  readily  than  the  glyko-cholate  of  soda  from  ox-bile.  Dog's 
bile  will  not  unfrequently  begin  to  crystallize  freely  in  five  to  six 
hours  after  precipitation  by  ether  (Fig.  50);  while 
in  ox-bile  it  is  usually  twelve,  and  often  twenty- 
four  or  even  forty-eight  hours  before  crystalliza- 
tion is  fully  established.  But  it  is  more  particu- 
larly in  their  reaction  with  the  salts  of  lead  that 
the  difference  between  these  substances  becomes 
manifest.  For  while  the  crystallizable  substance 
of  ox-bile  is  precipitated  by  acetate  of  lead,  that 
of  dog's  bile  is  not  affected  by  it.  If  dog's  bile 
be  evaporated  to  dryness,  extracted  with  absolute 
alcohol,  the  alcoholic  solution  precipitated  by 
ether,  and  the  ether  precipitate  then  dissolved 
in  water,  the  addition  of  acetate  of  lead  to  the 
watery  solution  produces  not  the  slightest  tur- 
bidity. If  subacetate  of  lead  be  then  added  in 
excess,  a  copious  precipitate  falls,  composed  of 
both  the  crystallizable  and  uncrystallizable  sub- 
stances. If  the  lead  precipitate  be  then  separated 
by  filtration,  washed,  and  decomposed,  as  above 
described,  by  carbonate  of  soda,  the  watery  solu- 
tion will  contain  the  re-formed  soda  salts  of  the 
bile.  The  watery  solution  may  then  be  evaporated  to  dryness, 
extracted  with  absolute  alcohol,  and  the  alcoholic  solution  precipi- 
tated by  ether ;  when  the  ether  precipitate  crystallizes  partially 
after  a  time,  as  in  fresh  bile.     Both  the  biliary  matters  of  dog's  bile 


Dog's  Bile,  extract- 
ed with  absolute  alcohol 
and  precipitated  with 
ether. 


THE    BILE, 


149 


Fig.  51. 


are  therefore  precipitable  by  sabacetateof  lead,  but  neither  of  them 
by  the  acetate.  Instead  of  calling  them,  consequently,  glykocholate 
and  tauro-cholate  of  soda,  we  shall  speak  of  them  simply  as  the 
"crystalline"  and  "resinous"  biliary  substances. 

In  cat's  bile,  the  biliary  substances  act  very  much  as  in  dog's 
bile.  The  ether- precipitate  of  the  alcoholic  solution  contains  here 
also  a  crystalline  and  a  resinous  substance;  both  of  which  are 
precipitable  from  their  watery  solution  by  subacetate  of  lead,  but 
neither  of  them  by  the  acetate. 

In  pig's  bile,  on  the  other  hand,  there  is  no  crystallizable  sub- 
stance, but  the  ether-precipitate  is  altogether  resinous  in  appearance. 
Notwithstanding  this,  its  watery  solution. precipitates  abundantly  by 
both  the  acetate  and  subacetate  of  lead. 

In  human  bile,  again,  there  is  no  crystallizable  substance.  We 
have  found  that  the  dried  bile,  extracted  with  absolute  alcohol, 
makes  a  clear,  brandy  red  solution,  which  precipitates  abundantly 
with  ether  in  excess ;  but  the  ether-precipitate,  if  allowed  to  stand, 
shows  no  sign  of  crystallization,  even  at  the  end 
of  three  weeks  (Fig.  51).  If  the  resinous  pre- 
cipitate be  separated  by  decantation  and  dissolved 
in  water,  it  precipitates,  as  in  the  case  of  pig's 
bile,  by  both  the  acetate  and  subacetate  of  lead. 
This  might,  perhaps,  be  attributed  to  the  pre- 
sence of  two  different  substances,  as  in  ox-bile, 
one  precipitated  by  the  acetate,  the  other  by  the 
subacetate  of  lead.  Such,  however,  is  not  the 
case.  For  if  the  watery  solution  be  precipitated 
by  the  acetate  of  lead  and  then  filtered,  the 
filtered  fluid  gives  no  precipitate  afterward  by  the 
subacetate ;  and  if  first  precipitated  by  the  sub- 
acetate, it  gives  no  precipitate  after  filtration  by 
the  acetate.  The  entire  biliary  ingredients, 
therefore,  of  human  bile  are  precipitated  by  both 
or  either  of  the  salts  of  lead. 

Dift'erent  kinds  of  bile  vary  also  in  other  re- 
spects; as,  for  example,  their  specific  gravity, 
the  depth  and  tinge  of  their  color,  the  quantity 
of  fat  which  they  contain,  &c.  &c.  We  have 
already  mentioned  the  variations  in  color  and  specific  gravity. 
The  alcoholic  solution  of  dried  ox-bile,  furthermore,  does  not  pre- 
cipitate at  all  on  the  addition  of  water ;  while  that  of  human  bile, 


Human  Bile,  ex- 
tracted with  absolute 
alcohol  and  precipitat- 
ed by  ether. 


150  THE    BILE. 

of  pig's  bile,  and  of  dog's  bile  precipitate  abundantly  with  distilled 
water,  owing  to  the  quantity  of  fat  which  they  hold  in  solution. 
These  variations,  however,  are  of  secondary  importance  compared 
with  those  which  we  have  already  mentioned,  and  which  show  that 
the  crystalline  and  resinous  substances  in  different  kinds  of  bile, 
though  resembling  each  other  in  very  many  respects,  are  yet  in 
reality  far  from  being  identical. 


TESTS  FOE    BILE. 

In  investigating  the  physiology  of  any  animal  fluid  it  is,  of 
course,  of  the  first  importance  to  have  a  convenient  and  reliable 
test  by  which  its  presence  may  be  detected.  For  a  long  time  the 
only  test  employed  in  the  case  of  bile,  was  that  which  depended  on 
a  change  of  color  produced  hy  oxidizing  substances.  If  the  bile,  for 
example,  or  a  mixture  containing  bile,  be  exposed  in  an  open 
glass  vessel  for  a  few  hours,  the  upper  layers  of  the  fluid,  which 
are  in  contact  with  the  atmosphere,  gradually  assume  a  greenish 
tinge,  which  becomes  deeper  with  the  length  of  time  which  elapses, 
and  the  quantity  of  bile  existing  in  the  fluid.  Nitric  acid,  added  to 
a  mixture  of  bile  and  shaken  up,  produces  a  dense  precipitate 
which  takes  a  bright  grass-green  hue.  Tincture  of  iodine  produces 
the  same  change  of  color,  when  added  in  small  quantity ;  and  pro- 
bably there  are  various  other  substances  which  would  have  the 
same  effect.  It  is  by  this  test  that  the  bile  has  so  often  been  recog- 
nized in  the  urine,  serous  effusions,  the  solid  tissues,  kc,  in  cases 
of  jaundice.  But  it  is  very  insufficient  for  anything  like  accurate 
investigation,  since  the  appearances  are  produced  simply  by  the 
action  of  an  oxidizing  agent  on  the  coloring  matter  of  the  bile.  A 
green  color  produced  by  nitric  acid  does  not,  therefore,  indicate  the 
presence  of  the  biliary  substances  proper,  but  only  of  the  biliver- 
dine.  On  the  other  hand,  if  the  coloring  matter  be  absent,  the 
biliary  substances  themselves  cannot  be  detected  by  it.  For  if  the 
biliary  substances  of  dog's  bile  be  precipitated  by  ether  from  an 
alcoholic  solution,  dissolved  in  w^ater  and  decolorized  by  animal 
charcoal,  the  colorless  watery  solution  will  then  give  no  green 
color  on  the  addition  of  nitric  acid  or  tincture  of  iodine,  though  it 
may  precipitate  abundantly  by  subacetate  of  lead,  and  give  the 
other  reactions  of  the  crystalline  and  resinous  biliary  matters  in  a 
perfectly  distinct  manner. 


TESTS    FOR    BILE.  151 

Petienkofer'' s  Test. — This  is  undoubtedly  the  best  test  yet  pro- 
posed for  the  detection  of  the  biliary  substances.  It  consists  in 
mixing  with  a  watery  solution  of  the  bile,  or  of  the  biliary  sub- 
stances, a  little  cane  sugar,  and  then  adding  sulphuric  acid  to  the 
mixture  until  a  red,  lake  or  purple  color  is  produced.  A  solution 
may  be  made  of  cane  sugar,  in  the  proportion  of  one  part  of  sugar  to 
four  parts  of  water,  and  kept  for  use.  One  drop  of  this  solution  is 
mixed  with  the  suspected  fluid,  and  the  sulphuric  acid  then  imme- 
diately added.  On  first  dropping  in  the  sulphuric  acid,  a  whitish 
precipitate  falls,  which  is  abundant  in  the  case  of  ox-bile,  less  so  in 
that  of  the  dog.  This  precipitate  redissolves  in  a  slight  excess  of 
sulphuric  acid,  which  should  then  continue  to  be  added  until  the 
mixture  assumes  a  somewhat  syrupy  consistency  and  an  opalescent 
look,  owing  to  the  development  of  minute  bubbles  of  air.  A  red 
color  then  begins  to  show  itself  at  the  bottom  of  the  test-tube,  and 
afterward  spreads  through  the  mixture,  until  the  whole  fluid  is  of 
a  clear,  bright,  cherry  red.  This  color  gradually  changes  to  a  lake, 
and  finally  to  a  deep,  rich,  opaque  purple.  If  three  or  four  vol- 
umes of  water  be  then  added  to  the  mixture,  a  copious  precipitate 
falls  down,  and  the  color  is  destroyed. 

Various  circumstances  modify,  to  some  extent,  the  rapidity  and 
distinctness  with  which  the  above  changes  are  produced.  If  the 
biliary  substances  be  present  in  large  quantity,  and  nearly  pure, 
the  red  color  shows  itself  at  once,  after  adding  an  equal  volume  of 
sulphuric  acid,  and  almost  immediately  passed  into  a  strong  purple. 
If  they  be  scanty,  on  the  other  hand,  the  red  color  may  not  show 
itself  for  seven  or  eight  minutes,  nor  the  purple  under  twenty 
or  twenty-five  minutes.  If  foreign  matters,  again,  not  of  a  biliary 
nature,  be  also  present,  they  are  apt  to  be  acted  on  by  the  sulphuric 
acid,  and,  by  becoming  discolored,  interfere  with  the  clearness  and 
brilliancy  of  the  tinges  produced.  On  this  account  it  is  indispen- 
sable, in  delicate  examinations,  to  evaporate  the  suspected  fluid  to 
dryness,  extract  the  dry  residue  with  absolute  alcohol,  precipitate 
the  alcoholic  solution  with  ether,  and  dissolve  the  ether  precipitate 
in  water  before  applying  the  test.  In  this  manner,  all  foreign  sub- 
stances which  might  do  harm  will  be  eliminated,  and  the  test  will 
succeed  without  difficulty. 

It  must  not  be  forgotten,  furthermore,  that  the  sugar  itself  is 
liable  to  be  acted  on  and  discolored  by  sulphuric  acid  when  added 
in  excess,  and  may  therefore  by  itself,  give  rise  to  confusion.  A  little 
care  and  practice,  however,  will  enable  the  experimenter  to  avoid 


152  THE    BILE. 

all  chance  of  deception  from  this  source.  AVhen  sulphuric  acid  is 
mixed  with  a  watery  solution  containing  cane  sugar,  after  it  has 
been  added  in  considerable  excess,  a  yellowish  color  begins  to  show 
itself,  owing  to  the  commencing  decomposition  of  the  sugar.  This 
color  gradually  deepens  until  it  has  become  a  dark,  dingy,  muddy 
brown ;  but  there  is  never  at  any  time  any  clear  red  or  purple 
color  unless  biliary  matters  be  present.  If  the  bile  be  present  in 
but  small  quantity,  the  colors  produced  by  it  may  be  modified  and 
obscured  by  the  dingy  yellow  and  brown  of  the  sugar;  but  even 
this  difficulty  may  be  avoided  by  paying  attention  to  the  following 
precautions.  In  the  first  place,  only  very  little  sugar  should  be 
added  to  the  suspected  fluid.  In  the  second  place,  the  sulphuric 
acid  should  be  added  very  gradually,  and  the  mixture  closely 
watched  to  detect  the  first  changes  of  color.  If  bile  be  present,  the 
red  color  peculiar  to  it  is  always  produced  before  the  yellowish 
tinge  which  indicates  the  decomposition  of  the  sugar.  When  the 
biliary  matters,  therefore,  are  present  in  small  quantity,  the  addi- 
tion of  sulphuric  acid  should  be  stopped  at  that  point,  and  the 
colors,  though  faint,  will  then  remain  clear,  and  give  unmistakable 
evidence  of  the  presence  of  bile. 

The  red  color  alone  is  not  sufficient  as  an  indication  of  bile  It 
is  in  fact  only  the  commencement  of  the  change  which  indicates  the 
biliary  matters.  If  these  matters  be  present,  the  color  passes,  as 
we  have  already  mentioned,  first  into  a  lake,  then  into  a  purple ; 
and  it  is  this  lake  and  purple  color  alone  which  can  be  regarded  as 
really  characteristic  of  the  biliary  reaction. 

It  is  important  to  observe  that  Pettenkofer's  reaction  is  produced 
by  the  presence  of  either  or  both  of  the  biliary  substances  proper ; 
and  is  not  at  all  dependent  on  the  coloring  matter  of  the  bile.  For 
if  the  two  biliary  substances,  crystalline  and  resinous,  be  extracted 
by  the  process  above  described,  and,  after  being  dissolved  in  water, 
decolorized  with  animal  charcoal,  the  watery  solution  will  still  give 
Pettenkofer's  reaction  perfectly,  though  no  coloring  matter  be  pre- 
sent, and  though  no  green  tinge  can  be  produced  by  the  addition 
of  nitric  acid  or  tincture  of  iodine.  If  the  two  biliary  substances 
be  then  separated  from  each  other,  and  tested  in  distinct  solutions, 
each  solution  will  give  the  same  reaction  promptly  and  completely. 

Various  objections  have  been  urged  against  this  test.  It  has 
been  stated  to  be  uncertain  and  variable  in  its  action.  Eobin  and 
Verdeil'  say  that  its  reactions  "do  not  belong  exclusively  to  the 

»  Op  cit.,  vol.  ii.  p.  468. 


VARIATIONS    AND    FUNCTIONS    OF    BILE.  153 

bile,  and  may  therefore  give  rise  to  mistakes."  Some  fatty  sub- 
stances and  volatile  oils  (olein,  oleic  acid,  oil  of  turpentine,  oil  of 
caraway)  have  been  stated  to  produce  similar  red  and  violet  colors, 
when  treated  with  sugar  and  sulphuric  acid.  These  objections, 
however,  have  not  much,  if  any,  practical  weight.  The  test  no  doubt 
requires  some  care  and  practice  in  its  application,  as  we  have  already 
pointed  out ;  but  this  is  the  case  also,  to  a  greater  or  less  extent, 
with  nearly  all  chemical  tests,  and  particularly  with  those  for  sub- 
stances of  organic  origin.  No  other  substance  is,  in  point  of  fact, 
liable  to  be  met  with  in  the  intestinal  fluids  or  the  blood,  which 
would  simulate  the  reactions  of  the  biliary  matters.  We  have 
found  that  the  fatty  matters  of  the  chyle,  taken  from  the  thoracic 
duct,  do  not  give  any  coloration  which  would  be  mistaken  for  that 
of  the  bile.  When  the  volatile  oils  (caraway  and  turpentine)  are 
acted  on  by  sulphuric  acid,  a  red  color  is  produced  which  after- 
ward becomes  brown  and  blackish,  and  a  peculiar,  tarry,  empyreu- 
raatic  odor  is  developed  at  the  same  time ;  but  we  do  not  get  the 
lake  and  purple  colors  spoken  of  above.  Finally,  if  the  precaution 
be  observed — first  of  extracting  the  suspected  matters  with  absolute 
alcohol,  then  precipitating  with  ether  and  dissolving  the  precipitate 
in  water,  no  ambiguity  could  result  from  the  presence  of  any  of  the 
above  substances. 

Pettenkofer's  test,  then,  if  used  with  care,  is  extremely  useful,  and 
may  lead  to  many  valuable  results.  Indeed,  no  other  test  than  this 
can  be  at  all  relied  on  to  determine  the  presence  or  absence  of  the 
biliary  substances  proper. 


VARIATIONS  AND  FUNCTIONS  OF  BILE. 

With  regard  to  the  entire  quantity  of  bile  secreted  daily,  we  have 
had  no  very  positive  knowledge,  until  the  experiments  of  Bidder 
and  Schmidt,  published  in  1852.*  These  experiments  were  per- 
formed on  cats,  dogs,  sheep,  and  rabbits,  in  the  following  manner. 
The  abdomen  was  opened,  and  a  ligature  placed  upon  the  ductus 
communis  choledochus,  so  as  to  prevent  the  bile  finding  its  way 
into  the  intestine.  An  opening  was  then  made  in  the  fundus  of 
the  gall-bladder,  by  which  the  bile  was  discharged  externally.  The 
bile,  so  discharged,  was  received  into  previously  weighed  vessels, 

'  Verdaungssaefte  und  StoffwechseL     Leipzig,  1852. 


154:  THE    BILE. 

and  its  quantity  accurately  determined.  Each  observation  usually 
occupied  about  two  hours,  during  which  period  the  temporary 
fluctuations  occasionally  observable  in  the  quantity  of  bile  dis- 
charged were  mutually  corrected,  so  fai;  as  the  entire  result  was 
concerned.  The  animal  was  then  killed,  weighed  and  carefully 
examined,  in  order  to  make  sure  that  the  biliary  duct  had  been 
securely  tied,  and  that  no  inflammatory  alteration  had  taken  place 
in  the  abdominal  organs.  The  observations  were  made  at  very 
different  periods  after  the  last  meal,  so  as  to  determine  the  influence 
exerted  by  the  digestive  process  upon  the  rapidity  of  the  secretion. 
The  average  quantity  of  bile  for  twenty-four  hours  was  then  calcu- 
lated from  a  comparison  of  the  above  results ;  and  the  quantity  of 
its  solid  ingredients  was  also  ascertained  in  each  instance  by  eva- 
porating a  portion  of  the  bile  in  the  water-bath,  and  weighing  the 
dry  residue. 

Bidder  and  Schmidt  found  in  this  way  that  the  daily  quantity  of 
bile  varied  considerably  in  different  species  of  animals.  It  was 
very  much  greater  in  the  herbivorous  animals  used  for  experiment 
than  in  the  carnivora.  The  results  obtained  by  these  observers 
are  as  follows  .• — 

For  every  pound  weight  of  the  entire  body  there  is  secreted 
during  24  hours 

Feesh  Bile.  Dry  Residue. 

In  the  cat 102  grains.  5.712  grains. 

"dog 140       "  6.916       " 

"       sheep 178       "  9.408       " 

"       rabbit 958       "  17.290      " 

Since,  in  the  human  subject,  the  digestive  processes  and  the 
nutritive  actions  generally  resemble  those  of  the  carnivora,  rather 
than  those  of  the  herbivora,  it  is  probable  that  the  daily  quantity 
of  bile  in  man  is  very  similar  to  that  in  the  carnivorous  animals. 
If  we  apply  to  the  human  subject  the  average  results  obtained  by 
Bidder  and  Schmidt  from  the  cat  and  dog,  we  find  that,  in  an  adult 
man,  weighing  140  pounds,  the  daily  quantity  of  the  bile  will  be 
certainly  not  less  than  16,940  grains,  or  very  nearly  2|-  pounds 
avoirdupois. 

It  is  a  matter  of  great  importance,  in  regard  to  the  bile,  as  well 
as  the  other  intestinal  fluids,  to  ascertain  whether  it  be  a  constant 
secretion,  like  the  urine  and  perspiration,  or  whether  it  be  intermit- 
tent, like  the  gastric  juice,  and  discharged  only  during  the  digestive 
process.     In  order  to  determine  this  point,  we  have  performed  the 


VARIATIONS    AND    FUNCTIONS    OF    BILE. 


155 


following  series  of  experiments  on  dogs.  The  animals  were  kept 
confined,  and  killed  at  various  periods  after  feeding,  sometimes 
by  the  inoculation  of  woorara,  sometimes  by  hydrocyanic  acid, 
but  most  frequently  by  section  of  the  medulla  oblongata.  The 
contents  of  the  intestine  were  then  collected  and  examined.  In 
all  instances,  the  bile  was  also  taken  from  the  gall-bladder,  and 
treated  in  the  same  way,  for  purposes  of  comparison.  The  intes- 
tinal contents  always  presented  some  peculiarities  of  appearance 
when  treated  with  alcohol  and  ether,  owing  probably  to  the  pre- 
sence of  other  substances  than  the  bile ;  but  they  always  gave 
evidence  of  the  presence  of  biliary  matters  as  well.  The  biliary 
substances  could  almost  always  be  recognized  by  the  microscope 
in  the  ether-precipitate  of  the  alcoholic  solution ;  the  resinous 
substance,  under  the  form  of  rounded,  oily-looking  drops  (Fig. 
52),  and  the  other,  under  the  form  of  crystalline  groups,  generally 
presenting  the  appearance  of  double  bundles  of  slender,  radiat- 
ing, slightly  curved  or 
wavy,  needle-shaped  crys- 
tals. These  substances,  dis- 
solved in  water,  gave  a  pur- 
ple color  with  sugar  and 
sulphuric  acid.  These  ex- 
periments were  tried  after 
the  animals  had  been  kept 
for  one,  two,  three,  five,  six, 
seven,  eight,  and  twelve 
days  "without  food.  The 
result  showed  that,  in  all 
these  instances,  bile  was 
present  in  the  small  intes- 
tine. It  is,  therefore,  plainly 
not  an  intermittent  secre- 
tion,-nor  one  which  is  con- 
cerned exclusively  in  the  digestive  process ;  but  its  secretion  is  con- 
stant, and  it  continues  to  be  discharged  into  the  intestine  for  many 
days  after  the  animal  has  been  deprived  of  food. 


Crystalline  and  Eesinohs  Biliary  Sub- 
STANOEs;  from  Small  Intestine  of  Dog,  after  two  days' 
fasting. 


The  next  point  of  importance  to  be  examined  relates  to  the  time 
after  feeding  at  which  the  hile  passes  into  the  intestine  in  the  greatest 
abundance.  Bidder  and  Schmidt  have  already  investigated  this 
point  in  the  following  manner.    They  operated,  as  above  described, 


156 


THE    BILE. 


by  tying  the  common  bile-duct,  and  tlien  opening  the  fundus  of  the 
gall-bladder,  so  as  to  produce  a  biliary  fistula,  by  which  the  whole 
of  the  bile  was  drawn  off.  By  doing  this  operation,  and  collecting 
and  weighing  the  fluid  discharged  at  different  periods,  they  came 
to  the  conclusion  that  the  flow  of  bile  begins  to  increase  within 
two  and  a  half  hours  after  the  introduction  of  food  into  the  stomach, 
but  that  it  does  not  reach  its  maximum  of  activity  till  the  end  of 
twelve  or  fifteen  hours.  Other  observers,  however,  have  obtained 
different  results.  Arnold,'  for  example,  found  the  quantity  to  be 
largest  soon  after  meals,  decreasing  again  after  the  fourth  hour. 
Kolliker  and  Miiller,^-  again,  found  it  largest  between  the  sixth  and 
eighth  hours.  Bidder  and  Schmidt's  experiments,  indeed,  strictly 
speaking,  show  only  the  time  at  which  the  bile  is  most  actively 
secreted  by  the  liver,  but*  not  when  it  is  actually  discharged  into 
the  intestine. 

Our  own  experiments,  bearing  on  this  point,  were  performed  on 

dogs,  by  making  a  permanent 
^^^'  ^^'  duodenal  fistulse,  on  the  same 

plan  that  gastric  fistulee  have  so 
often  been  established  for  the 
examination  of  the  gastric  juice. 
(Fig.  53.)  An  incision  was  made 
through  the  abdominal  walls,  a 
short  distance  to  the  right  of 
the  median  line,  the  floating 
portion  of  the  duodenum  drawn 
up  toward  the  external  wound, 
opened  by  a  longitudinal  inci- 
sion, and  a  silver  tube,  armed 
at  each  end  with  a  narrow 
projecting  collar  or  flange,  in- 
serted into  it  by  one  extremity, 
five  and  a  half  inches  below  the 
pylorus,  and  two  and  a  half 
inches  below  the  orifice  of  the 
lower  pancreatic  duct.  The 
other  extremity  of  the  tube  was 
left  projecting  from  the  external 
opening  in  the  abdominal  pa- 
rietes,  the  parts  secured  by  sutures,  and  the  wound  allowed  to  heal. 


Duodenal  Fistula. — a.  Stomach.  6.  Duo- 
denum, c,  c,  c.  Pancreas ;  its  two  ducts  are  seen 
opening  into  the  duodenum,  one  near  the  orifice  of 
the  biliary  duct,  d,  the  other  a  short  distance 
lower  down.  e.  Silver  tube  passing  through  the 
abdominal  walls  and  opening  into  the  duodenum. 


'  In  Am.  Journ.  Med.  Sci.,  April,  1856. 


Ibid.,  April,  1857. 


VARIATIONS    AND    FUNCTIONS    OF    BILE. 


157 


After  cicatrization  was  complete,  and  the  animal  had  entirely 
recovered  his  healthy  condition  and  appetite,  the  intestinal  fluids 
were  drawn  oflf  at  various  intervals  after  feeding,  and  their  contents 
examined.  This  operation,  which  is  rather  more  difficult  than  that 
of  making  a  permanent  gastric  fistula,  is  nevertheless  exceedingly 
useful  when  it  succeeds,  since  it  enables  us  to  study,  not  only  the 
time  and  rate  of  the  biliary  discharge,  but  also,  as  mentioned  in  a 
previous  chapter  (Chap.  VI.),  many  other  extremely  interesting 
matters  connected  with  intestinal  digestion. 

In  order  to  ascertain  the  absolute  quantity  of  bile  discharged 
into  the  intestine,  and  its  variations  during  digestion,  the  duodenal 
fluids  were  drawn  off,  for  fifteen  minutes  at  a  time,  at  various 
periods  after  feeding,  collected,  weighed,  and  examined  separately, 
as  follows:  each  separate  quantity  was  evaporated  to  dryness,  its 
dry  residue  extracted  with  absolute  alcohol,  the  alcoholic  solution 
precipitated  with  ether,  and  the  ether-precipitate,  regarded  as  repre- 
senting the  amount  of  biliary  matters  present,  dried,  weighed,  and 
then  treated  with  Pettenkofer's  test,  in  order  to  determine,  as  nearly 
as  possible,  their  degree  of  purity  or  admixture.  The  result  of 
these  experiments  is  given  in  the  following  table.  At  the  eigh- 
teenth hour  so  small  a  quantity  of  fluid  was  obtained,  that  the 
amount  of  its  biliary  ingredients  was  not  ascertained.  It  reacted 
perfectly,  however,  with  Pettenkofer's  test,  showing  that  bile  was 
really  present. 


Time  after 

Quautity  of  fluid 

Dry  residue 

Quantity  of 

Proportion  of 

feeding. 

iu  l.i  minutes. 

of  same. 

biliary  matters. 

biliary  matters 
to  dry  residue. 

Immediately 

640  grains 

33  grains 

10  grains 

.30 

1  hour 

1,990       " 

105       " 

4       " 

.03 

3  hours 

780      " 

60       " 

4      " 

.07 

6     " 

750      " 

73       " 

H   " 

.05 

9     " 

860       " 

78      " 

4i     " 

.06 

12     " 

325       " 

23       " 

3f     " 

.16 

15     " 

347       " 

18       " 

4      " 

.22 

18     " 









.    21     « 

384       " 

11       " 

1       '• 

.09 

24    " 

163       " 

H   " 

3i     " 

.34 

25     " 

151       " 

5       " 

3       " 

.60 

From  this  it  appears  that  the  bile  passes  into  the  intestine  in  by 
far  the  largest  quantity  immediately  after  feeding,  and  within  the 
first  hour.  After  that  time  its  discharge  remains  pretty  constant ; 
not  varying  much  from  four  grains  of  solid  biliary  matters  every 
fifteen  minutes,  or  sixteen  grains  per  hour.  The  animal  used  for 
the  above  observations  weighed  thirty-six  and  a  half  pounds. 


158  THE    BILE. 

The  next  point  to  be  ascertained  with  regard  to  this  question  is 
the  following,  viz :  What  hecomes  of  the  bile  in  its  passage  through 
the  intestine?  Our  experiments,  performed  with  a  view  of  settling 
this  point,  were  tried  on  dogs.  The  animals  were  fed  with  fresh 
meat,  and  then  killed  at  various  intervals  after  the  meals,  the  abdo- 
men opened,  ligatures  placed  upon  the  intestine  at  various  points, 
and  the  contents  of  its  upper,  middle,  and  lower  portions  collected 
and  examined  separately.  The  results  thus  obtained  show  that, 
under  ordinary  circumstances,  the  bile,  which  is  quite  abundant  in 
the  duodenum  and  upper  part  of  the  small  intestine,  diminishes  in 
quantity  from  above  downward,  and  is  not  to  be  found  in  the  large 
intestine.  The  entire  quantity  of  the  intestinal  contents  also  dimi- 
nishes, and  their  consistency  increases,  as  we  approach  the  ileo- 
caecal  valve;  and  at  the  same  time  their  color  changes  from  a  light 
yellow  to  a  dark  bronze  or  blackish-green,  which  is  always  strongly 
pronounced  in  the  last  quarter  of  the  small  intestine. 

The  contents  of  the  small  and  large  intestine  were  furthermore 
evaporated  to  dryness,  extracted  with  absolute  alcohol,  and  the 
alcoholic  solutions  precipitated  with  ether ;  the  quantity  of  ether 
precipitate  being  regarded  as  representing  approximatively  that  of 
the  biliary  substances  proper.  The  result  showed  that  the  quantity 
of  this  ether  precipitate  is,  both  positively  and  relatively,  very  much 
less  in  the  large  intestine  than  in  the  small.  Its  proportion  to  the 
entire  solid  contents,  is  only  one-fifth  or  one-sixth  as  great  in  the 
large  intestine  as  it  is  in  the  small.  But  even  this  inconsiderable 
quantity,  found  in  the  contents  of  the  large  intestine,  does  not  con- 
sist of  biliary  matters ;  for  the  watery  solutions  being  treated  with 
sugar  and  sulphuric  acid,  those  from  both  the  upper  and  lower 
portions  of  the  small  intestine  always  gave  Pettenkofer's  reaction 
promptly  and  perfectly  in  less  than  a  minute  and  a  half;  while  in 
that  from  the  large  intestine  no  red  or  purple  color  was  produced, 
even  at  the  end  of  three  hours. 

The  small  intestine  consequently  contains,  at  all  times,  substances 
giving  all  the  reactions  of  the  biliary  ingredients;  while  in  the 
contents  of  the  large  intestine  no  such  substances  can  be  recognized 
by  Pettenkofer's  test. 

The  biliary  matters,  therefore,  disappear  in  their  passage  through 
the  intestine. 

In  endeavoring  to  ascertain  what  is  the  precise /M?-/c^?■o?^  of  the  Ule 
in  the  intestine,  our  first  object  must  be  to  determine  what  part,  if 


VAKIATIONS    AND    FUNCTIONS    OF    BILE.  159 

any,  it  takes  in  tlie  digestive  process.  As  the  liver  is  situated,  like 
the  salivary  glands  and  the  pancreas,  in  the  immediate  vicinity  of 
the  alimentary  canal,  and  like  them,  discharges  its  secretion  into 
the  cavity  of  the  intestine,  it  seems  at  first  natural  to  regard  the 
bile  as  one  of  the  digestive  fluids.  We  have  previously  shown, 
however,  that  the  digestion  of  all  the  different  elements  of  the  food 
is  provided  for  by  other  secretions ;  and  furthermore,  if  we  examine 
experimentally  the  digestive  power  of  bile  on  alimentary  substances, 
we  obtain  only  a  negative  result.  Bile  exerts  no  special  action  upon 
either  albuminoid,  starchy,  or  oleaginous  matters,  when  mixed  with 
them  in  test-tubes  and  kept  at  the  temperature  of  100°  F.  It  has 
therefore,  apparently,  no  direct  influence  in  the  digestion  of  these 
substances. 

Furthermore  it  appears,  from  the  experiments  detailed  above, 
that  the  secretion  of  the  bile  and  its  discharge  into  the  intestine 
are  not  confined  to  the  periods  of  digestion,  but  take  place  con- 
stantly, and  continue  even  after  the  animal  has  been  kept  for  many 
days  without  food.  These  facts  would  lead  us  to  regard  the  bile  as 
simply  an  excrementitious fluid ;  containing  only  ingredients  resulting 
from  the  waste  and  disintegration  of  the  animal  tissues,  and  not 
intended  to  perform  any  particular  function,  digestive  or  otherwise, 
but  merely  to  be  eliminated  from  the  blood,  and  discharged  from 
the  system.  The  same  view  is  more  or  less  supported,  also,  by  the 
following  facts,  viz: — 

1st.  The  bile  is  produced,  unlike  all  the  other  animal  secretions, 
from  venous  blood ;  that  is,  the  blood  of  the  portal  vein,  which  has 
already  become  contaminated  by  circulation  through  the  abdominal 
organs,  and  may  be  supposed  to  contain  disorganized  and  effete 
ingredients ;  and 

2d.  Its  complete  suppression  produces,  in  the  human  subject, 
symptoms  of  poisoning  of  the  nervous  system,  analogous  to  those 
which  follow  the  suppression  of  the  urine,  or  the  stoppage  of  respi- 
ration, and  the  patient  dies,  usually  in  a  comatose  condition,  at  the 
end  of  ten  or  twelve  days. 

The  above  circumstances,  taken  together,  would  combine  to 
make  it  appear  that  the  bile  is  simply  an  excrementitious  fluid,  not 
necessary  or  useful  as  a  secretion,  but  only  destined,  like  the  urine, 
to  be  eliminated  and  discharged.  Nevertheless  experiment  has 
shown  that  such  is  not  the  case ;  and  that,  in  point  of  fact,  it  is 
necessary  for  the  life  of  the  animal,  not  only  that  the  bile  be  secreted 
and  discharged,  but  furthermore  that  it  be  discharged   into   the 


160  THE    JBILE. 

intestine,  and  pass  through  the  tract  of  the  alimentary  canal.  The 
most  satisfactory  experiments  of  this  kind  are  those  of  Bidder  and 
Schmidt,^  in  which  they  tied  the  common  biliary  duct  in  dogs,  and 
then  established  a  permanent  fistula  in  the  fundus  of  the  gall-bladder 
through  which  the  bile  was  allowed  to  flow  by  a  free  external  orifice. 
In  this  manner  the  bile  was  effectually  excluded  from  the.  intestine, 
but  at  the  same  time  was  freely  and  wholly  discharged  from  the 
body,  by  the  artificial  fistula.  If  the  bile  therefore  were  simply  an 
excrementitious  fluid,  its  deleterious  ingredients  being  all  eliminated 
as  usual,  the  animals  would  not  suffer  any  serious  injury  from  this 
operation.  If,  on  the  contrary,  they  were  found  to  suffer  or  die  in 
consequence  of  it,  it  would  show  that  the  bile  has  really  some  im- 
portant function  to  perform  in  the  intestinal  canal,  and  is  not  simply 
excrementitious  in  its  nature. 

The  result  showed  that  the  effects  of  such  an  experiment  were 
fatal  to  the  animal.  Four  dogs  only  survived  the  immediate  effects 
of  the  operation,  and  were  afterward  frequently  used  for  purposes 
of  experiment.  One  of  them  was  an  animal  from  which  the  spleen 
had  been  previously  removed,  and  whose  appetite,  as  usual  after 
this  operation,  was  morbidly  ravenous;  his  sj^stem,  accordingly, 
being  placed  under  such  unnatural  conditions  as  to  make  him  an 
unfit  subject  for  further  experiment.  In  the  second  animal  that 
survived,  the  communication  of  the  biliary  duct  with  the  intestine 
became  re-established  after  eighteen  days,  and  the  experiment  con- 
sequently had  no  result.  In  the  remaining  two  animals,  however, 
everything  was  successful.  The  fistula  in  the  gall-bladder  became 
permanently  established ;  and  the  bile-duct,  as  was  proved  subse- 
quently by  post-mortem  examination,  remained  completely  closed, 
so  that  no  bile  found  its  way  into  the  intestine.  Both  these  ani- 
mals died;  one  of  them  at  the  end  of  twenty-seven  days,  the  other 
at  the  end  of  thirty-six  days.  In  both,  the  symptoms  were  nearly 
the  same,  viz.,  constant  and  progressive  emaciation,  which  proceeded 
to  such  a  degree  that  nearly  every  trace  of  fat  disappeared  from  the 
body.  The  loss  of  flesh  amounted,  in  one  case  to  more  than  two- 
fifths,  and  in  the  other  to  nearly  one-half  the  entire  weight  of  the 
animal.  There  was  also  a  falling  off  of  the  hair,  and  an  unusually 
disagreeable,  putrescent  odor  in  the  feces  and  in  the  breath.  Not- 
withstanding this,  the  appetite,  remained  good.  Digestion  was  not 
essentially  interfered  with,  and  none  of  the  food  was  discharged 

'  Op.  cit.,  p.  103. 


VAEIATIONS    AND    FUNCTIONS    OF    BILE.  161 

with  the  feces ;  but  there  was  much  rumbling  and  gurgling  in  the 
intestines,  and  abundant  discharge  of  flatus,  more  strongly  marked 
in  one  instance  than  in  the  other.  There  was  no  pain ;  and  death 
took  place,  at  last,  without  any  violent  symptoms,  but  by  a  simple 
and  gradual  failure  of  the  vital  powers. 

How  is  it,  then,  that  although  the  bile  be  not  an  active  agent  in 
digestion,  its  presence  in  the  alimentary  canal  is  still  essential  to 
life  ?  What  office  does  it  perform  there,  and  how  is  it  finally  dis- 
posed of? 

We  have  already  shown  that  the  bile  disappears  in  its  passage 
through  the  intestine.  This  disappearance  may  be  explained  in 
two  different  ways.  First,  the  biliary  matters  may  be  actually  re- 
absorbed from  the  intestine,  and  taken  up  by  the  bloodvessels ;  or 
secondly,  they  may  be  so  altered  and  decomposed  by  the  intestinal 
fluids  as  to  lose  the  power  of  giving  Pettenkofer's  reaction  with 
sugar  and  sulphuric  acid,  and  so  pass  off  with  the  feces  in  an 
insoluble  form.  Bidder  and  Schmidt'  have  finally  determined  this 
point  in  a  satisfactory  manner ;  and  have  demonstrated  that  the 
biliary  substances  are  actually  reabsorbed,  by  showing  that  the 
quantity  of  sulphur  present  in  the  feces  is  far  inferior  to  that 
contained  in  the  biliary  ingredients  as  they  are  discharged  into  the 
intestine. 

These  observers  collected  and  analyzed  all  the  feces  passed,  dur- 
ing five  days,  by  a  healthy'dog,  weighing  17.7  pounds.  The  entire 
fecal  mass  during  this  period  weighed  1508.15  grains, 

(  Water 874.20  grains. 

Containing  I  g^^.^^,^^.^^^ g33_g5      , 


1508.15 

The  solid  residue  was  composed  as  follows: — 

Neutral  fat,  soluble  in  ether    .         .    43.710  grains. 

Fat,  witli  traces  of  biliary  matter  .    77.035      " 

Alcohol  extract  with  biliary  matter     58.900  containing  1.085  grs.  of  sulphur. 

Substances  not  of  a  biliary  nature 

extracted  by  muriatic  acid  and 

hot  alcohol  ....  148.800  containing  1.302  grs.  of  sulphur. 

2.387 
Fatty  acids  with  oxide  of  iron         .    98.425 
Residue  consisting  of  hair,  sand,  &c.,  207.080 

633.950 

'  Op.  cit.,  p.  217. 
11 


162  THE    BILE. 

Now,  as  it  lias  already  been  shown  that  the  dog  secretes,  during 
24  hours,  6.916  grains  of  solid  biliary  matter  for  every  pound  weight 
of  the  whole  body,  the  entire  quantity  of  biliary  matter  secreted 
in  five  days  by  the  above  animal,  weighing  17.7  pounds,  must  have 
been  612.5  grains,  or  nearly  as  much  as  the  whole  weight  of  the 
dried  feces.  But  furthermore,  the  natural  proportion  of  sulphur 
in  dog's  bile  (derived  from  the  uncrystallizable  biliary  matter),  is  six 
per  cent,  of  the  dry  residue.  The  612.5  grains  of  dry  bile,  secreted 
during  five  days,  contained  therefore  86.75  grains  of  sulphur. 
But  the  entire  quantity  of  sulphur,  existing  in  any  form  in  the 
feces,  was  5.952  grains ;  and  of  this  only  2.387  grains  were  derived 
from  substances  which  could  have  been  the  products  of  biliary 
matters — the  remainder  being  derived  from  the  hairs  which  are 
always  contained  in  abundance  in  the  feces  of  the  dog.  That  is, 
not  more  than  one-fifteenth  part  of  the  sulphur,  originally  present 
in  the  bile,  could  be  detected  in  the  feces.  As  this  is  a  simple 
chemical  element,  not  decomposable  by  any  known  means,  it  must, 
accordingly,  have  been  reabsorbed  from  the  intestine. 

We  have  endeavored  to  complete  the  evidence  thus  furnished  by 
Bidder  and  Schmidt,  and  to  demonstrate  directly  the  reabsorption 
of  the  biliary  matters,  by  searching  for  them  in  the  ingredients  of 
the  portal  blood.  AVe  have  examined,  for  this  purpose,  the  portal 
blood  of  dogs,  killed  at  various  periods  after  feeding.  The  animals 
were  killed  by  section  of  the  medulla  oblongata,  a  ligature  imme- 
diately placed  on  the  portal  vein,  while  the  circulation  was  still 
active,  and  the  requisite  quantity  of  blood  collected  by  opening 
the  vein.  The  blood  was  sometimes  immediately  evaporated  to 
dryness  by  the  water  bath.  Sometimes  it  was  coagulated  by  boil- 
ing in  a  porcelain  capsule,  over  a  spirit  lamp,  with  water  and  an 
excess  of  sulphate  of  soda,  and  the  filtered  watery  solution  after- 
ward examined.  But  most  frequently  the  blood,  after  being  col- 
lected from  the  vein,  was  coagulated  by  the  gradual  addition  of 
three  times  its  volume  of  alcohol  at  ninety-five  per  cent.,  stirring 
the  mixture  constantly,  so  as  to  make  the  coagulation  gradual  and 
uniform.  It  was  then  filtered,  the  moist  mass  remaining  on  the  filter 
subjected  to  strong  pressure  in  a  linen  bag,  by  a  porcelain  press, 
and  the  fluid  thus  obtained  added  to  that  previously  filtered.  The 
entire  spirituous  solution  was  then  evaporated  to  dryness,  the  dry 
residue  extracted  with  absolute  alcohol,  and  the  alcoholic  solution 
treated  as  usual,  with  ether,  &c.,  to  discover  the  presence  of  biliary 
matters.    In  every  instance,  blood  was  taken  at  the  same  time  from 


VARIATIONS    AND    FUNCTIONS    OF    BILE.  163 

the  jugular,  or  tlie  abdominal  vena  cava,  and  treated  in  the  same 
way  for  purposes  of  comparison. 

"We  have  examined  the  blood,  in  this  way,  one,  four,  six,  nine, 
eleven  and  a  half,  twelve,  and  twenty  hours  after  feeding.  As  the 
result  of  these  examinations,  we  have  found  that  in  the  venous  blood, 
both  of  the  portal  vein  and  of  the  general  circulation,  there  exists 
a  substance  soluble  in  water  and  absolute  alcohol,  and  precipitable 
by  ether  from  its  alcoholic  solution.  This  substance  is  often  consi- 
derably more  abundant  in  the  portal  blood  than  in  that  taken  from 
the  general  venous  system.  It  adheres  closely  to  the  sides  of  the 
glass  after  precipitation,  so  that  it  is  always  difficult,  and  often  im- 
possible, to  obtain  enough  of  it,  mixed  with  ether,  for  microscopic 
examination.  It  dissolves,  also,  like  the  biliary  substances,  with 
great  readiness  in  water ;  but  in  no  instance  have  we  ever  been  able 
to  obtain  from  it  such  a  satisfactory  reaction  with  Pettenkofer's  test, 
as  would  indicate  the  presence  of  bile.  This  is  not  because  the 
reaction  is  masked,  as  might  be  suspected,  by  some  of  the  other 
ingredients  of  the  blood ;  for  if  at  the  same  time,  two  drops  of  bile 
be  added  to  half  an  ounce  of  blood  taken  from  the  abdominal  vena 
cava,  and  the  two  specimens  treated  alike,  the  ether  precipitate  may 
be  considerably  more  abundant  in  the  case  of  the  portal  blood ;  and 
yet  that  from  the  blood  of  the  vena  cava,  dissolved  in  water,  will 
give  Pettenkofer's  reaction  for  bile  perfectly,  while  that  of  the  por- 
tal blood  will  give  no  such  reaction. 

Notwithstanding,  then,  the  irresistible  evidence  afforded  by  the 
experiments  of  Bidder  and  Schmidt,  that  the  biliary  matters  are 
really  taken  up  by  the  portal  blood,  we  have  failed  to  recognize 
them  there  by  Pettenkofer's  test.  They  must  accordingly  undergo 
certain  alterations  in  the  intestine,  previously  to  their  absorption,  so 
that  they  no  longer  give  the  ordinary  reaction  of  the  biliary  sub- 
stances. We  cannot  say,  at  present,  precisely  what  these  alterations 
are ;  but  they  are  evidently  transformations  of  a  catalytic  nature, 
produced  by  the  contact  of  the  bile  with  the  intestinal  juices. 

The  bile,  therefore,  is  a  secretion  which  has  not  yet  accomplished 
its  function  when  it  is  discharged  from  the  liver  and  poured  into  the 
intestine.  On  the  contrary,  during  its  passage  through  the  intestine 
it  is  still  in  the  interior  of  the  body,  in  contact  with  glandular  sur- 
faces, and  mingled  with  various  organic  substances,  the  ingredients 
of  the  intestinal  fluids,  which  act  upon  it  as  catalytic  bodies,  and 
produce  in  it  new  transformations.  This  may  account  for  the  fact 
stated  above,  that  the  bile,  though  a  constant  and  uninterrupted 


164  THE    BILE. 

secretion,  is  nevertheless  poured  into  the  intestine  in  the  greatest 
abundance  immediately  after  a  hearty  meal.  This  is  not  because  it 
is  to  take  any  direct  part  in  the  digestion  of  the  food ;  but  because 
the  intestinal  fluids,  being  themselves  present  at  that  time  in  the 
greatest  abundance,  can  then  act  upon  and  decompose  the  greatest 
quantity  of  bile.  At  all  events,  the  biliary  ingredients,  after  being 
altered  and  transformed  in  the  intestine,  as  they  might  be  in  the 
interior  of  a  glandular  organ,  re-enter  the  blood  under  some  new 
form,  and  are  carried  away  by  the  circulation,  to  complete  their 
function  in  some  other  part  of  the  body. 


FOKMATION    OF    SUGAR    IN    THE    LIVER.  165 


CHAPTER   IX. 

FORMATION   OF   SUGAR   IN   THE   LIVER. 

Beside  the  secretion  of  bile,  the  liver  performs  also  another 
exceedingly  important  function,  viz.,  the  -produclion  of  sugar  by  a 
metamorphosis  of  some  of  its  organic  ingredients. 

Under  ordinary  circumstances  a  considerable  quantity  of  sac- 
charine matter  is  introduced  with  the  food,  or  produced,  from 
starchy  substances,  by  the  digestive  process  in  the  intestinal  canal. 
In  man  and  the  herbivorous  animals,  accordingly,  an  abundant  * 
supply  of  sugar  is  derived  from  these  sources ;  and,  as  we  have 
already  shown,  the  sugar  thus  introduced  is  necessary  for  the  proper 
support  of  the  vital  functions.  For  though  the  saccharine  matter 
absorbed  from  the  intestine  is  destroyed  by  decomposition  soon 
after  entering  the  circulation,  yet  the  chemical  changes  by  which 
its  decomposition  is  eifected  are  themselves  necessary  for  the  proper 
constitution  of  the  blood,  and  the  healthy  nutrition  of  the  tissues. 
Experiment  shows,  however,  that  the  system  does  not  depend,  for  • 
its  supply  of  sugar,  entirely  upon  external  sources ;  but  that  sac- 
charine matter  is  also  produced  independently,  in  the  tissue  of  the 
liver,  whatever  may  be  the  nature  of  the  food  upon  which  the 
animal  subsists. 

This  important  function  was  first  discovered  by  M.  Claude 
Bernard'  in  1848,  and  described  by  him  under  the  name  of  the 
glycogenic  function  of  the  liver. 

It  has  long  been  known  that  sugar  may  be  abundantly  secreted, 
under  some  circumstances,  when  no  vegetable  matters  have  been 
taken  with  the  food.  The  milk,  for  example,  of  all  animals,  car- 
nivorous as  Avell  as  herbivorous,  contains  a  notable  proportion  of 
sugar  ;  and  the  quantity  thus  secreted,  during  lactation,  is  in  some 
instances  very  great.  In  the  human  subject,  also,  when  suffering 
from  diabetes,  the  amount  of  saccharine  matter  discharged  with  the 

'  Nouvelle  Fonction  du  Foie.     Paris,  1853. 


166  FORMATION    OF    SUGAR    IN    THE    LIVER. 

urine  has  often  appeared  to  be  altogether  out  of  proportion  to  that 
which  could  be  accounted  for  by  the  vegetable  substances  taken  as 
food.  The  experiments  of  Bernard,  the  most  important  of  which 
we  have  repeatedly  confirmed,  in  common  with  other  investigators, 
show  that  in  these  instances  most  of  the  sugar  has  an  internal 
origin,  and  that  it  first  makes  its  appearance  in  the  tissue  of  the 
liver. 

If  a  carnivorous  animal,  as,  for  example,  a  dog  or  a  cat,  be  fed 
for  several  days  exclusively  upon  meat,  and  then  killed,  the  liver 
alone  of  all  the  internal  organs  is  found  to  contain  sugar  among  its 
other  ingredients.  For  this  purpose,  a  portion  of  the  organ  should 
be  cut  into  small  pieces,  reduced  to  a  pulp  by  grinding  in  a  mortar 
with  a  little  water,  and  the  mixture  coagulated  by  boiling  with  an 
excess  of  sulphate  of  soda,  in  order  to  precipitate  the  albuminous 
and  coloring  matters.  The  filtered  fluid  will  then  reduce  the  oxide 
of  copper,  with  great  readiness,  on  the  application  of  Trommer's 
test.  A  decoction  of  the  same  tissue,  mixed  with  a  little  yeast,  will 
also  give  rise  to  fermentation,  producing  alcohol  and  carbonic  acid, 
as  is  usual  with  saccharine  solutions.  On  the  contrary,  the  tissues 
of  the  spleen,  the  kidneys,  the  lungs,  the  muscles,  &c,,  treated  in  the 
same  way,  give  no  indication  of  sugar,  and  do  not  reduce  the  salts 
of  copper.  Every  otlier  organ  in  the  body  may  be  entirely  desti- 
tute of  sugar,  but  the  liver  always  contains  it  in  considerable  quan- 
tity, provided  the  animal  be  healthy.  Even  the  blood  of  the  portal 
vein,  examined  by  a  similar  process,  contains  no  saccharine  element, 
and  yet  the  tissue  of  the  organ  supplied  by  it  shows  an  abundance 
of  saccharine  ingredients. 

It  is  remarkable  for  how  long  a  time  the  liver  will  continue  to 
exhibit  the  presence  of  sugar,  after  all  external  supplies  of  this 
substance  have  been  cut  off.  Bernard  kept  two  dogs  under  his  own 
observation,  one  for  a  period  of  three,  the  other  of  eight  months,^ 
during  which  period  they  were  confined  strictly  to  a  diet  of  animal 
food  (boiled  calves'  heads  and  tripe),  and  then  killed.  Upon  ex- 
amination, the  liver  was  found,  in  each  instance,  to  contain  a 
proportion  of  sugar  fully  equal  to  that  present  in  the  organ  under 
ordinary  circumstances. 

The  sugar,  therefore,  which  is  found  in  the  liver  after  death,  is  a 
normal  ingredient  of  the  hepatic  tissue.  It  is  not  formed  in  other 
parts  of  the  body,  nor  absorbed  from  the  intestinal  canal,  but  takes 

'  Nouvelle  Fonction  du  Foie,  p.  50. 


FORMATION    OF    SUGAR    IN    THE    LIVER.  167 

its  origin  in  the  liver  itself;  it  is  produced,  as  a  new  formation, 
by  a  secreting  process  in  the  tissue  of  the  organ. 

The  presence  of  sugar  in  the  liver  is  common  to  all  species  of 
animals,  so  far  as  is  yet  known.  Bernard  found  it  invariably  in 
monkeys,  dogs,  cats,  rabbits,  the  horse,  the  ox,  the  goat,  the  sheep, 
in  birds,  in  reptiles,  and  in  most  kinds  of  fish.  It  was  only  in  two 
species  of  fish,  viz.,  the  eel  and  the  ray  (Murasna  angnilla  and  Raia 
batis),  that  he  sometimes  failed  to  discover  it;  but  the  failure  in 
these  instances  was  apparently  owing  to  the  commencing  putres- 
cence of  the  tissue,  by  which  the  sugar  had  probably  been  destroyed. 
In  the  fresh  liver  of  the  human  subject,  examined  after  death  from 
accidental  violence,  sugar  was  found  to  be  present  in  the  proportion 
of  1.10  to  2.14  per  cent,  of  the  entire  weight  of  the  organ. 

The  following  list  shows  the  average  percentage  of  sugar  present 
in  the  healthy  liver  of  man  and  different  species  of  animals,  accord- 
ing to  the  examinations  of  Bernard : — 

Pekcentage  of  Sugar  in  the  Liver.  « 

In  man    ....     1.68  In  ox        .         .         .         .     2.30 


"  monkey 
"  dog      . 
"  cat 
"  rabbit 
"  sheep 


2.15  "  horse  ....  4.08 

1.69  "  goat     ....  3.89 

1.94  "  birds  ....  1.49 

1.94  "  reptiles        .         .         .  1.04 

2.00  "  fish      .         .         .         .  1.45 


With  regard  to  the  nature  and  properties  of  the  liver  sugar,  it 
resembles  very  closely  glucose,  or  the  sugar  of  starch,  the  sugar  of 
honey,  and  the  sugar  of  milk,  though  it  is  not  absolutely  identical 
with  either  one  of  them.  Its  solution  reduces,  as  we  have  seen,  the 
salts  of  copper  in  Trommer's  test,  and  becomes  colored  brown  when 
boiled  with  caustic  potass.  It  ferments  very  readily,  also,  when 
mixed  witb  yeast  and  kept  at  the  temperature  of  70°  to  100°  F. 
It  is  distinguished  from  all  the  other  sugars,  according  to  Bernard,^ 
by  the  readiness  with  which  it  becomes  decomposed  in  the  blood — 
since  cane  sugar  and  beet  root  sugar,  if  injected  into  the  circulation 
of  a  living  animal,  pass  through  the  system  without  sensible  decom- 
position, and  are  discharged  unchanged  with  the  urine ;  sugar  of 
milk  and  glucose,  if  injected  in  moderate  quantity,  are  decomposed 
in  the  blood,  but  if  introduced  in  greater  abundance  make  their 
appearance  also  in  the  urine ;  while  a  solution  of  liver  sugar,  though 
injected  in  much  larger  quantity  than  either  of  the  others,  may  dis- 

'  Lemons  de  Physiologic  Experimentale.     Paris,  1855,  p.  213. 


168  rORMATIOX    OF    SUGAR    IN    THE    LIVER. 

appear  altogether  in  the  circulation,  without  passing  off'  by  the 
kidneys. 

This  substance  is  therefore  a  sugar  of  animal  origin,  similar  in 
its  properties  to  other  varieties  of  saccharine  matter,  derived  from 
different  sources. 

The  sugar  of  the  liver  is  not  produced  in  the  blood  by  a  direct 
decomposition  of  the  elements  of  the  circulating  fluid  in  the  vessels 
of  the  organ,  but  takes  its  origin  in  the  solid  substance  of  the  hepatic 
tissue^  as  a  natural  ingredient  of  its  organic  texture.  The  blood 
which  may  be  pressed  out  from  a  liver  recently  extracted  from  the 
body,  it  is  true,  contains  sugar ;  but  this  sugar  it  has  absorbed  from 
the  tissues  of  the  organ  in  which  it  circulates.  This  is  demonstrated 
by  the  singular  fact  that  the  fresh  liver  of  a  recently  killed  animal, 
though  it  may  be  entirely  drained  of  blood  and  of  the  sugar  which 
it  contained  at  the  moment  of  death,  will  still  continue  for  a  certain 
time  to  produce  a  saccharine  substance.  If  such  a  liver  be  injected 
with  water  by  the  portal  vein,  and  all  the  blood  contained  in  its 
vessels  washed  out  by  the  stream,  the  water  which  escapes  by  the 
hepatic  vein  will  still  be  found  to  contain  sugar.  M.  Bernard  has 
found'  that  if  all  the  sugar  contained  in  a  fresh  liver  be  extracted  in 
this  manner  by  a  prolonged  watery  injection,  so  that  neither  the 
water  which  escapes  by  the  hepatic  vein,  nor  the  substance  of  the 
liver  itself,  contain  any  further  traces  of  sugar,  and  if  the  organ  be 
then  laid  aside  for  twenty-four  hours,  both  the  tissue  of  the  liver  and 
the  fluid  which  exudes  from  it  will  be  found  at  the  end  of  that  time 
to  have  again  become  highly  saccharine.  The  sugar,  therefore,  is 
evidently  not  produced  in  the  blood  circulating  through  the  liver, 
but  in  the  substance  of  the  organ  itself.  Once  having  originated 
in  the  hepatic  tissue,  it  is  absorbed  thence  by  the  blood,  and  trans- 
ported by  the  circulation,  as  we  shall  hereafter  show,  to  other  parts 
of  the  body. 

The  sugar  which  thus  originates  in  the  tissue  of  the  liver,  is  pro- 
duced by  a  mutual  decomposition  and  transformation  of  various 
other  ingredients  of  the  hepatic  substance ;  these  chemical  changes 
being  a  part  of  the  nutritive  processes  by  which  the  tissue  of  the 
organ  is  constantly  sustained  and  nourished.  There  is  probably  a 
series  of  several  different  transformations  which  take  place  in  this 
manner,  the  details  of  which  are  not  yet  known  to  us.  It  has  been 
discovered,  however,  that  one  change  at  least  precedes  the  final 

'  Gazette  Hebdomadaire,  Paris,  Oct.  5,  1855. 


FORMATION    OF    SUGAR    IN    THE    LIVER.  169 

production  of  saccharine  matter ;  and  that  the  sugar  itself  is  pro- 
duced by  the  transformation  of  another  peculiar  substance,  of  ante- 
rior formation.  This  substance,  which  precedes  the  formation  of 
sugar,  and  which  is  itself  produced  in  the  tissue  of  the  liver,  is 
known  by  the  name  of  the  glycogenic  matter^  or  glycogene. 

This  glj^cogenic  matter  may  be  extracted  from  the  liver  in  the 
following  manner.  The  organ  is  taken  immediately  from  the  body 
of  the  recently  killed  animal,  cut  into  small  pieces,  and  coagulated  by 
being  placed  for  a  few  minutes  in  boiling  water.  This  is  in  order 
to  prevent  the  albuminous  liquids  of  the  organ  from  acting  upon 
the  glj'cogenic  matter  and  decomposing  it  at  a  medium  temperature. 
The  coagulated  tissue  is  then  drained,  placed  in  a  mortar,  reduced 
to  a  pulp  by  bruising  and  grinding,  and  afterward  boiled  in  dis- 
tilled water  for  a  quarter  of  an  hour  or  more,  by  which  the  glyco- 
genic matter  is  extracted  and  held  in  solution  by  the  boiling  water. 

The  liquid  of  decoction,  which  should  be  as  concentrated  as  pos- 
sible, must  then  be  expressed,  strained,  and  filtered,  after  which  it 
appears  as  a  strongly  opalescent  fluid,  of  a  slightly  yellowish  tinge. 
The  glycogenic  matter  which  is  held  in  solution  may  be  precipi- 
tated by  the  addition  to  the  filtered  fluid  of  five  times  its  volume  of 
alcohol.  The  precipitate,  after  being  repeatedly  washed  with 
alcohol  in  order  to  remove  sugar  and  biliary  matters,  may  then  be 
redissolved  in  distilled  water.  It  may  be  precipitated  from  its 
watery  solution  either  by  alcohol  in  excess  or  by  crystallizable 
acetic  acid,  in  both  of  which  it  is  entirely  insoluble,  and  mav  be 
afterward  kept  in  the  dry  state  for  an  indefinite  time  without  losing 
its  properties. 

The  glycogenic  matter,  obtained  in  this  way,  is  regarded  as 
intermediate  in  its  nature  and  properties  between  hydrated  starch 
and  dextrine.  Its  ultimate  composition,  according  to  M.  Pelouze," 
is  as  follows : — 

When  brought  into  contact  with  iodine,  it  produces  a  coloration 
varying  from  violet  to  a  deep,  clear,  maroon  red.  It  does  not 
reduce  the  salts  of  copper  in  Troramer's  test,  nor  does  it  ferment 
when  placed  in  contact  with  yeast  at  the  proper  temperature.  It 
does  not,  therefore,  of  itself  contain  sugar.  It  may  easily  be  con- 
verted into  sugar,  however,  by  contact  with  any  of  the  animal 
ferments,  as,  for  example,  those  contained  in  the  saliva  or  in  the 

'  Journal  de  Physiologie,  Paris,  1858,  p.  552. 


170  FORMATION    OF    SUGAR    IN"    THE    LIVER. 

blood.  If  a  solution  of  glycogenic  matter  be  mixed  witb  fresli 
human  saliva,  and  kept  for  a  few  minutes  at  the  temperature  of 
100°  F.,  the  mixture  will  then  be  found  to  have  acquired  the  power 
of  reducing  the  salts  of  copper  and  of  entering  into  fermentation  by 
contact  with  yeast.  The  glycogenic  matter  has  therefore  been 
converted  into  sugar  by  a  process  of  catalysis,  in  the  same  manner 
as  vegetable  starch  would  be  transformed  under  similar  conditions. 

The  glycogenic  matter  which  is  thus  destined  to  be  converted 
into  sugar,  is  formed  in  the  liver  by  the  processes  of  nutrition.  It 
may  be  extracted,  as  we  have  seen  above,  from  the  hepatic  tissue 
of  carnivorous  animals,  and  is  equally  present  when  they  have  been 
exclusively  confined  for  many  days  to  a  meat  diet.  It  is  not  in- 
troduced with  the  food ;  for  the  fleshy  meat  of  the  herbivora  does 
not  contain  it  in  appreciable  quantity,  though  these  animals  so 
constantly  take  starchy  substances  with  their  food.  In  them,  the 
starchy  matters  are  transformed  into  sugar  by  digestion,  and  the 
sugar  so  produced  is  rapidly  destroyed  after  entering  the  circula- 
tion ;  so  that  usually  neither  saccharine  nor  starchy  substances  are 
to  be  discovered  in  the  muscular  tissue.  M.  Poggiale'  found  that 
in  very  many  experiments,  performed  by  a  commission  of  the 
French  Academy  for  the  purpose  of  examining  this  subject,  glyco- 
genic matter  was  detected  in  ordinary  butcher's  meat  only  once. 
We  have  also  found  it  to  be  absent  from  the  fresh  meat  of  the 
bullock's  heart,  when  examined  in  the  manner  described  above, 
l^evertheless,  in  dogs  fed  exclusively  upon  this  food  for  eight  days, 
glycogenic  matter  may  be  found  in  abundance  in  the  liver,  while 
it  does  not  exist  in  other  parts  of  the  body,  as  the  spleen,  kidney, 
lungs,  &c. 

Furthermore,  in  a  dog  fed  exclusively  for  eight  days  upon  the 
fresh  meat  of  the  bullock's  heart,  and  then  killed  four  hours  after 
a  meal  of  the  same  food,  at  which  time  intestinal  absorption  is 
going  on  in  full  vigor,  the  liver  contains,  as  above  mentioned,  both 
glycogenic  matter  and  sugar;  but  neither  sugar  nor  glycogenic  mat- 
ter can  be  found  in  the  blood  of  the  portal  vein,  when  subjected  to 
a  similar  examination. 

The  glycogenic  matter,  accordingly,  does  not  originate  from  any 
external  source,  but  is  formed  in  the  tissue  of  the  liver ;  where  it 
is  soon  afterward  transformed  into,  sugar,  while  still  forming  a  part 
of  the  substance  of  the  organ. 

'  Journal  de  Pbysiologie,  Paris,  1858,  p.  558. 


FOEMATION    OF    SUGAE    IN    THE    LIVER.  171 

The  formation  of  sugar  in  the  liver  is  therefore  a  function  com- 
posed of  two  distinct  and  successive  processes,  viz :  first,  the  forma- 
tion, in  the  hepatic  tissue,  of  a  glycogenic  matter,  having  some 
resemblance  to  dextrine ;  and  secondly,  the  conversion  of  this  gly- 
cogenic matter  into  sugar,  by  a  process  of  catalysis  and  transforma- 
tion. 

The  sugar  thus  produced  in  the  substance  of  the  liver  is  absorbed 
from  it  by  the  blood  circulating  in  its  vessels.  The  mechanism  of 
this  absorption  is  probably  the  same  with  that  which  goes  on  in 
other  parts  of  the  circulation.  It  is  a  process  of  transudation  and 
endosmosis,  by  which  the  blood  in  the  vessels  takes  up  the  saccha- 
rine fluids  of  the  liver,  during  its  passage  through  the  organ. 
While  the  blood  of  the  portal  vein,  .therefore,  in  an  animal  fed 
exclusively  upon  meat,  contains  no  sugar,  the  blood  of  the  hepatic 
vein,  as  it  passes  upward  to  the  heart,  is  always  rich  in  saccharine 
ingredients.  This  difference  can  easily  be  demonstrated  by  exa- 
mining comparatively  the  two  kinds  of  blood,  portal  and  heptic, 
from  the  recently  killed  animal.  The  blood  in  its  passage  through 
the  liver  is  found  to  have  acquired  a  new  ingredient,  and  shows, 
upon  examination,  all  the  properties  of  a  saccharine  liquid. 

The  sugar  produced  in  the  liver  is  accordingly  to  be  regarded  as 
a  true  secretion,  formed  by  the  glandular  tissue  of  the  organ,  by  a 
similar  process  to  that  of  other  glandular  secretions.  It  differs 
from  the  latter,  not  in  tbe  manner  of  its  production,  but  only  in 
the  mode  of  its  discharge.  For  while  the  biliary  matters  produced 
in  the  liver  are  absorbed  by  the  hepatic  ducts  and  conducted  down- 
ward to  the  gall-bladder  and  the  intestine,  the  sugar  is  absorbed  by 
the  bloodvessels  of  the  organ  and  carried  upward,  by  the  hepatic 
veins,  toward  the  heart  and  the  general  circulation. 

The  production  of  sugar  in  the  liver  during  health  is  a  constant 
process,  continuing,  in  many  cases,  for  several  days  after  the  animal 
has  been  altogether  deprived  of  food.  Its  activity,  howev&r,  like 
that  of  most  other  secretions,  is  subject  to  periodical  augmentation 
and  diminution.  Under  ordinary  circumstances,  the  sugar,  which 
is  absorbed  by  the  blood  from  the  tissue  of  the  liver,  disappears 
very  soon  after  entering  the  circulation.  As  the  bile  is  transformed 
in  the  intestine,  so  the  sugar  is  decomposed  in  the  blood.  We  are 
not  yet  acquainted,  however,  with  the  precise  nature  of  the  changes 
which  it  undergoes  after  entering  the  vascular  system.  It  is  very 
probable,  according  to  the  views  of  Lehmann  and  Robin,  that  it  is 
at  first  converted  into  lactic  acid  (CgHgOg),  which  decomposes  in 


172  FORMATION    OF    SUGAR    IN    THE    LIVER. 

turn  the  alkaline  carbonates,  setting  free  carbonic  acid,  and  form 
ing  lactates  of  soda  and  potass.  But  whatever  be  the  exact  mode 
of  its  transformation,  it  is  certain  that  the  sugar  disappears  rapidly; 
and  while  it  exists  in  considerable  quantity  in  the  liver  and  in  the 
blood  of  the  hepatic  veins  and  the  right  side  of  the  heart,  it  is  not 
usually  to  be  found  in  the  pulmonary  veins  nor  in  the  blood  of  the 
general  circulation. 

About  two  and  a  half  or  three  hours,  however,  after  the  inges- 
tion of  food,  according  to  the  investigations  of  Bernard,  the  circu- 
lation of  blood  through  the  portal  system  and  the  liver  becomes 
considerably  accelerated.  A  larger  quantity  of  sugar  is  then  pro- 
duced in  the  liver  and  carried  away  from  the  organ  by  the  hepatic 
veins ;  so  that  a  portion  of  it  then  escapes  decomposition  while 
passing  through  the  lungs,  and  begins  to  appear  in  the  blood  of 
the  arterial  system.  Soon  afterward  it  appears  also  in  the  blood 
of  the  capillaries  ;  and  from  four  to  six  hours  after  the  commence- 
ment of  digestion  it  is  produced  in  the  liver  so  much  more  rapidly 
than  it  is  destroyed  in  the  blood,  that  the  surplus  quantity  circulates 
throughout  the  body,  and  the  blood  everywhere  has  a  slightly 
saccharine  character.  It  does  not,  however,  in  the  healthy  condi- 
tion, make  its  appearance  in  any  of  the  secretions. 

After  the  sixth  hour,  this  unusual  activity  of  the  sugar  producing 
function  begins  again  to  diminish ;  and  the  transformation  of  the 
sugar  in  the  circulation  going  on  as  before,  it  gradually  disappears 
as  an  ingredient  of  the  blood.  Finally,  the  ordinary  equilibrium 
between  its  production  and  its  decomposition  is  re-established,  and 
it  can  no  longer  be  found  except  in  the  liver  and  in  that  part  of 
the  circulatory  system  which  is  between  the  liver  and  the  lungs. 
There  is,  therefore,  a  periodical  increase  in  the  amount  of  unde- 
composed  sugar  in  the  blood,  as  we  have  already  shown  to  be  the 
case  with  the  fatty  matter  absorbed  during  digestion ;  but  this  in- 
crease is  soon  followed  by  a  corresponding  diminution,  and  during 
the  greater  portion  of  the  time  its  decomposition  keeps  pace  with 
its  production,  and  it  is  consequently  prevented  from  appearing  in 
the  blood  of  the  general  circulation. 

There  are  produced,  accordingly,  in  the  liver,  two  different  secre- 
tions, viz.,  bile  and  sugar.  Both  of  them  originate  by  transforma- 
tion of  the  ingredients  of  the  hepatic  tissue,  from  which  they  are 
absorbed  by  two  different  sets  of  vessels.  The  bile  is  taken  up  by 
the  biliary  ducts,  and  by  them  discharged  into  the  intestine;  while 
the  sugar  is  carried  off  by  the  hepatic  veins,  to  be  decomposed  in  the 
circulation,  and  become  subservient  to  the  nutrition  of  the  blood. 


THE    SPLEEN.  173 


CHAPTER   X. 

THE    SPLEEN. 

The  spleen  is  an  exceedingly  vascular  organ,  situated  in  the 
vicinity  of  the  great  pouch  of  the  stomach  and  supplied  abund- 
antly by  branches  of  the  coeliac  axis.  Its  veins,  like  those  of  the 
digestive  abdominal  organs,  form  a  part  of  the  great  portal  system, 
and  conduct  the  blood  which  has  passed  through  it  to  the  liver, 
before  it  mingles  again  with  the  general  current  of  the  circulation. 

The  spleen  is  covered  on  its  exterior  by  an  investing  membrane 
or  capsule,  which  forms  a  protective  sac,  containing  the  soft  pulp 
of  Avhich  the  greater  part  of  the  organ  is  composed.  This  capsule, 
in  the  spleen  of  the  ox,  is  thick,  whitish  and  opaque,  and  is  com- 
posed to  a  great  extent  of  yellow  elastic  tissue.  It  accordingly 
possesses,  in  a  high  degree,  the  physical  property  of  elasticity,  and 
may  be  widely  stretched  without  laceration ;  returning  readily  to 
its  original  size  as  soon  as  the  extending  force  is  relaxed. 

In  the  carnivorous  animals,  on  the  other  hand,  the  capsule  of 
the  spleen  is  thinner,  and  more  colorless  and  transparent.  It  con- 
tains here  but  very  little  elastic  tissue,  being  composed  mostly  of 
smooth,  involuntary  muscular  fibres,  connected  in  layers  by  a  little 
intervening  areolar  tissue.  In  the  herbivorous  animals,  accordingly, 
the  capsule  of  the  spleen  is  simply  elastic,  while  in  the  carnivora  it 
is  contractile. 

In  both  instances,  however,  the  elastic  and  contractile  properties 
of  the  capsule  subserve  a  nearly  similar  purpose.  There  is  every 
reason  to  believe  that  the  spleen  is  subject  to  occasional  and  per- 
haps regular  variations  in  size,  owing  to  the  varying  condition  of 
the  abdominal  circulation.  Dr.  William  Dobson^  found  that  the 
size  of  the  organ  increased,  from  the  third  hour  after  feeding  up  to 
the  fifth ;  when  it  arrived  at  its  maximum,  gradually,  decreasing 
after  that  period.     When  these  periodical  congestions  take  place, 

'  In  Gray,  on  tlie  Structure  and  Uses  of  the  Spleen.     London,  1854,  p.  40. 


174.  THE    SPLEEN. 

the  organ  becoming  turgid  with  blood,  the  capsule  is  distended ; 
and  limits,  by  its  resisting  power,  the  degree  of  tumefaction  to 
which  the  spleen  is  liable.  When  the  disturbing  cause  has  again 
passed  away,  and  the  circulation  is  about  to  return  to  its  ordinary 
condition,  the  elasticity  of  the  capsule  in  the  herbivora  and  its  con- 
tractility in  the  carnivora,  compress  the  soft  vascular  tissue  within, 
and  reduce  the  organ  to  its  original  dimensions.  This  contractile 
action  of  the  investing  capsule  can  be  readily  seen  in  the  dog  or 
the  cat,  by  opening  the  abdomen  while  digestion  is  going  on,  ex- 
posing the  spleen  and  removing  it,  after  ligature  of  its  vessels. 
When  first  exposed,  the  organ  is  plump  and  rounded,  and  presents 
externally  a  smooth  and  shining  surface.  But  as  soon  as  it  has 
been  removed  from  the  abdomen  and  its  vessels  divided,  it  begins 
to  contract  sensibly,  becomes  reduced  in  size,  stiffj  and  resisting  to 
the  touch ;  while  its  surface,  at  the  same  time,  becomes  uniformly 
wrinkled,  by  the  contraction  of  its  muscular  fibres. 

In  its  interior,  the  substance  of  the  spleen  is  traversed  everywhere 
by  slender  and  ribbon-like  cords  of  fibrous  tissue,  which  radiate 
from  the  sheath  of  its  principal  arterial  trunks,  and  are  finally 
attached  to  the  internal  surface  of  its  investing  capsule.  These 
fibrous  cords,  or  irabeculce,  as  they  are  called,  by  their  frequent 
branching  and  mutual  interlacement,  form  a  kind  of  skeleton  or 
framework  by  which  the  soft  splenic  pulp  is  embraced,  and  the 
shape  and  integrity  of  the  organ  maintained.  They  are  composed 
of  similar  elements  to  those  of  the  investing  capsule,  viz.,  elastic 
tissue  and  involuntary  muscular  fibres,  united  with  each  other  by 
a  varying  quantity  of  the  fibres  of  areolar  tissue. 

The  interstices  between  the  trabeculae  of  the  spleen  are  occupied 
by  the  splenic  pulp;  a  soft,  reddish  substance,  which  contains, 
beside  a  few  nerves  and  lymphatics,  capillary  bloodvessels  in  great 
profusion,  and  certain  whitish  globular  bodies,  which  may  be  re- 
garded as  the  distinguishing  anatomical  elements  of  the  organ,  and 
which  are  termed  the  Malpighian  bodies  of  the  spleen. 

The  Malpighian  bodies  are  very  abundant,  and  are  scattered 
throughout  the  splenic  pulp,  being  most  frequently  attached  to  the 
sides,  or  at  the  point  of  bifurcation  of  some  small  artery.  They 
are  readily  visible  to  the  naked  eye  in  the  spleen  of  the  ox,  upon  a 
fresh  section^of  the  organ,  as  minute,  whitish,  rounded  bodies,  which 
may  be  separated,  by  careful  manipulation,  from  the  surrounding 
parts.  In  the  carnivorous  animals,  on  the  other  hand,  and  in  the 
human  subject,  it  is  more  difficult  to  distinguish  them  by  the  un- 


THE    SPLEEN.  176 

aided  eye,  though  they  always  exist  in  the  spleen  in  a  healthy 
condition.  Their  average  diameter,  according  to  Kcilliker,  is  y^\  of 
an  inch.  They  consist  of  a  closed  sac,  or  capsule,  containing  in 
its  interior  a  viscid,  semi-solid  mass  of  cells,  cell-nuclei,  and  homo- 
geneous substance.  Each  Malpighian  body  is  covered,  on  its  exte- 
rior, by  a  network  of  fine  capillary  bloodvessels;  and  it  is  now 
perfectly  well  settled,  by  the  observations  of  various  anatomists 
(Kcilliker,  Busk,  Huxley,  &c.),  that  bloodvessels  also  penetrate  into 
the  substance  of  the  Malpighian  body,  and  there  form  an  internal 
capillary  plexus. 

The  spleen  is  accordingly  a  glandular  organ,  analogous  in  its 
minute  structure  to  the  solitary  and  agminated  glands  of  the  small 
intestine,  and  to  the  lymphatic  glands  throughout  the  body.  Like 
them,  it  is  a  gland  without  an  excretory  duct ;  and  resembles  also, 
in  this  respect,  the  thyroid  and  thymus  glands  and  the  supra-renal 
capsules.  All  these  organs  have  a  structure  which  is  evidently 
glandular  in  its  nature,  and  yet  the  name  of  glands  has  been  some- 
times refused  to  them  because  they  have,  as  above  mentioned,  no 
duct,  and  produce  apparently  no  distinct  secretion.  We  have 
already  seen,  however,  that  a  secretion  may  be  produced  in  the 
interior  of  a  glandular  organ,  like  the  sugar  in  the  substance  of  the 
liver,  and  yet  not  be  discharged  by  its  excretory  duct.  The  veins 
of  the  gland,  in  this  instance,  perform  the  part  of  excretory  ducts. 
They  absorb  the  new  materials,  and  convey  them,  through  the 
medium  of  the  blood,  to  other  parts  of  the  body,  where  they  suffer 
subsequent  alterations,  and  are  finally  decomposed  in  the  circula- 
tion. 

The  action  of  such  organs  is  consequently  to  modify  the  consti- 
tution of  the  blood.  As  the  blood  passes  through  their  tissue,  it 
absorbs  from  the  glandular  substance  certain  materials  which  it  did 
not  previously  contain,  and  which  are  necessary  to  the  perfect  con- 
stitution of  the  circulating  fluid.  The  blood,  as  it  passes  out  from 
the  organ,  has  therefore  a  different  composition  from  that  which  it 
possessed  before  its  entrance;  and  on  this  account  the  name  of 
vascular  glands  has  been  applied  to  all  the  glandular  organs  above 
mentioned,  which  are  destitute  of  excretory  ducts,  and  is  eminently 
applicable  to  the  spleen. 

The  precise  alteration,  however,  which  is  effected  in  the  blood 
during  its  passage  through  the  splenic  tissue,  has  not  yet  been 
discovered.  Various  hypotheses  have  been  advanced  from  time  to 
time,  as  to  the  processes  which  go  on  in  this  organ ;  many  of  them 


176  THE    SPLEEIST. 

vague  and  indefinite  in  character,  and  some  of  them  directly  con- 
tradictory of  each  other.  None,  however,  have  yet  been  offered 
which  are  entirely  satisfactory  in  themselves,  or  which  rest  on  suffi- 
ciently reliable  evidence. 

A  very  remarkable  fact  with  regard  to  the  spleen  is  that  it  may 
be  entirely  removed,  in  many  of  the  lower  animals,  without  its  loss 
producing  any  serious  permanent  injury.  This  experiment  has 
been  frequently  performed  by  various  observers,  and  we  have  our- 
selves repeated  it  several  times  with  similar  results.  The  organ 
may  be  easily  removed,  in  the  dog  or  the  cat,  by  drawing  it  out 
of  the  abdomen,  through  an  opening  in  the  median  line,  placing  a 
few  ligatures  upon  the  vessels  of  the  gastro-splenic  omentum,  and 
then  dividing  the  vessels  between  the  ligatures  and  the  spleen.  The 
wound  usually  heals  without  difficulty ;  and  if  the  animal  be  killed 
some  weeks  afterward,  the  only  remaining  trace  of  the  operation 
is  an  adhesion  of  the  omentum  to  the  inner  surface  of  the  abdominal 
parietes,  at  the  situation  of  the  original  wound. 

The  most  constant  and  permanent  effect  of  a  removal  of  the 
spleen  is  an  unusual  increase  of  the  appetite.  This  symptom  we 
have  observed  in  some  instances  to  be  excessively  developed ;  so 
that  the  animal  would  at  all  times  throw  himself,  with  an  unnatural 
avidity,  upon  any  kind  of  food  offered  him.  We  have  seen  a  dog, 
subjected  to  this  operation,  afterward  feed  without  hesitation  upon 
the  flesh  of  other  dogs;  and  even  devour  greedily  the  entrails, 
taken  warm  from  the  abdomen  of  the  recently  killed  animal.  The 
food  taken  in  this  unusual  quantity  is,  however,  perfectly  well 
digested ;  and  the  animal  will  often  gain  very  perceptibly  in  weight. 
In  one  instance,  a  cat,  in  whom  the  unnatural  appetite  was  marked 
though  not  excessive,  increased  in  weight  from  five  to  six  pounds, 
in  the  course  of  a  little  less  than  two  months;  and  at  the  same 
time  the  fur  became  sleek  and  glossy,  and  there  was  a  considerable 
improvement  in  the  general  appearance  of  the  animal. 

Another  symptom,  which  usually  follows  removal  of  the  spleen, 
is  an  unnatural  ferocity  of  disposition.  The  animal  will  frequently 
attack  others,  of  its  own  or  a  different  species,  without  any  appa- 
rent cause,  and  without  any  regard  to  the  difference  of  size,  strength, 
&c.  This  symptom  is  sometimes  equally  excessive  with  that  of  an 
unnatural  appetite ;  while  in  other  instances  it  shows  itself  only  in 
occasional  outbursts  of  irritability  and  violence. 

Neither  of  the  symptoms,  however,  which  we  have  just  de- 
scribed, appear  to  exert  any  permanently  injurious  effect  upon  the 


THE    SPLEEN".  177 

animal  Avhich  has  been  subjected  to  the  operation;  and  life  may  be 
prolonged  for  an  indefinite  period,  without  any  serious  disturbance 
of  the  nutritive  process,  after  the  spleen  has  been  completely 
extirpated. 

We  must  accordingly  regard  the  spleen,  not  as  a  single  organ, 
but  as  associated  with  others,  which  may  completely,  or  to  a  great 
extent,  perform  its  functions  after  its  entire  removal.  We  have 
already  noticed  the  similarity  in  structure  between  the  spleen  and 
the  mesenteric  and  lymphatic  glands ;  a  similarity  which  has  led 
some  writers  to  regard  them  as  more  or  less  closely  associated  with 
each  other  in  function,  and  to  consider  the  spleen  as  an  unusually 
developed  lymphatic  or  mesenteric  gland.  It  is  true  that  this 
organ  is  provided  with  a  comparatively  scanty  supply  of  lymphatic 
vessels ;  and  the  chyle,  which  is  absorbed  from  the  intestine,  does 
not  pass  through  the  spleen,  as  it  passes  through  the  remaining 
mesenteric  glands.  Still,  the  physiological  action  of  the  spleen 
may  correspond  with  that  of  the  other  lymphatic  glands,  so  far  as 
regards  its  influence  on  the  blood;  and  there  can  be  little  doubt 
that  its  function  is  shared,  either  by  them  or  by  some  other  glan- 
dular organs,  which  become  unnaturally  active,  and  more  or  less 
perfectly  supply  its  place  after  its  complete  removal. 


12 


178  THE    BLOOD. 


CHAPTER   XI. 

THE    BLOOD. 

The  blood,  as  it  exists  in  its  natural  condition,  while  circulating 
in  the  vessels,  is  a  thick  opaque  fluid,  varying  in  color  in  different 
parts  of  the  body  from  a  brilliant  scarlet  to  a  dark  purple.  It  has 
a  slightly  alkaline  reaction,  and  a  specific  gravity  of  1055.  It 
is  not,  however,  an  entirely  homogeneous  fluid,  but  is  found  on 
microscopic  examination  to  consist,  first,  of  a  nearly  colorless, 
transparent,  alkaline  fluid,  termed  the  plasma,  containing  water, 
fibrin,  albumen,  salts,  &c.,  in  a  state  of  mutual  solution;  and, 
secondly,  of  a  large  number  of  distinct  cells,  or  corpuscles,  the 
blood- globules,  swimming  freely  in  the  liquid  plasma.  These  glo- 
bules, which  are  so  small  as  not  to  be  distinguished  by  the  naked 
eye,  by  being  mixed  thus  abundantly  with  the  fluid  plasma,  give 
to  the  entire  mass  of  the  blood  an  opaque  appearance  and  a  uni- 
form red  color. 


BLOOD-GLOBULES. 

On  microscopic  examination  it  is  found  that  the  globules  of  the 
blood  are  of  two  kinds,  viz.,  red  and  white ;  of  these  the  red  are 
by  far  the  most  abundant. 

The  o'ed  globules  of  the  blood  present,  under  the  microscope,  a 
perfectly  circular  outline  and  a  smooth  exterior.  (B'ig.  54.)  Their 
size  varies  somewhat,  in  human  blood,  even  in  the  same  specimen. 
The  greater  number  of  them  have  a  transverse  diameter  of  3500  ^^ 
an  inch;  but  there  are  many  smaller  ones  to  be  seen,  which  are 
not  more  than  gJ^o  or  even  4o'oo  of  ^^  ii^^h  in  diameter.  Their 
form  is  that  of  a  spheroid,  very  much  flattened  on  its  opposite 
surfaces,  somewhat  like  a  round  biscuit,  or  a  thick  piece  of  money 
with  rounded  edges.  The  blood-globule  accordingly,  when  seen 
flatwise,  presents  a  comparatively  broad  surface  and  a  circular  out- 


BLOOD-GLOBULES. 


179 


Human  Blood-globules.  —  a.  Red  globules, 
seeu  fiatwi-e.  h.  Red  globules,  seen  edgewise,  e. 
White  globule. 


line  (a);  but  if  it  be  made  to  roll  over,  it  will  present  itself  edge- 
wise during  its  rotation  and  assume  the  flattened  form  indicated 
at  h.  The  thickness  of  the 
globule,  seen  in  this  position, 
is  about  y  15^55  of  an  inch,  or 
a  little  less  than  one-fifth  of 
its  transverse  diameter. 

When  the  globules  are  exa- 
mined lying  upon  their  broad 
surfaces,  it  can  be  seen  that 
these  surfaces  are  not  exactly 
flat,  but  that  there  is  on  each 
side  a  slight  central  depres- 
sion, so  that  the  rounded 
edges  of  the  blood-globule 
are  evidently  thicker  than  its 
middle  portion.  This  ine- 
quality produces  a  remark- 
able optical  effect.  The  sub- 
stance of  which  the  blood-globule  is  composed  refracts  light  more 
strongly  than  the  fluid  plasma.  Therefore,  when  examined  with  the 
microscope,  by  transmitted  light,  the  thick  edges  of  the  globules 
act  as  double  convex  lenses,  and  concentrate  the  light  above  the 
level  of  the  fluid.  Conse- 
quently, if  the  object-glass  be 
carried  upward  by  the  ad- 
justing screw  of  the  micro- 
scope, and  lifted  away  from 
tbe  stage,  so  that  the  blood- 
globules  fall  beyond  its  fo- 
cus, their  edges  will  appear 
brighter.  But  the  central  por- 
tion of  each  globule,  being 
excavated  on  both  sides,  acts 
as  a  double  concave  lens,  and 
disperses  the  light  from  a 
point  below  the  level  of  the 
fluid.  It,  therefore,  grows 
brighter  as  the  object-glass 
is  carried  downward,  and  the 
object  falls  within  its  focus. 


Red  Globules  op  the  Blood, 
beyond  the  focus  of  the  microscope. 


seen  a  little 


An  alternating  appearance  of  the 


180 


THE    BLOOD. 


blood-globules  may,  therefore,  be  produced  by  viewing  tliem  first 
beyond  and  then  within  the  focus  of  the  instrument.  When  be- 
yond the  focus,  the  globules  will  be  seen  with  a  bright  rim  and  a 

darlv  centre.  (Fig.  55.)  When 
within  it,  they  will  appear 
with  a  dark  rim  and  a  bright 
centre.  (Fig.  56.) 

The  blood-globules  accord- 
ingly have  the  form  of  a 
thickened  disk  with  rounded 
edges  and  a  double  central 
excavation.  They  have,  con- 
sequently, been  sometimes 
called  "blood-disks,"  instead 
of  blood-globules.  The  term 
"  disk,"  however,  does  not  in- 
dicate their  exact  shape,  any 


more  than  the  other ;  and 
the  term  "  blood-corpuscle," 
which  is  also  sometimes  used,  does  not  indicate  it  at  all.  And 
although  the  term  "  blood-globule"  may  not  be  precisely  a  correct 
one,  still  it  is  the  most  convenient ;  and  need  not  give  rise  to  any 
confusion,  if  we  remember  the  real  shape  of  the  bodies  designated 
by  it.  This  term  will,  consequently,  be  employed  whenever  we 
have  occasion  to  speak  of  the  blood-globules  in  the  following  pages. 

Within  a  minute  after  being 


The   same,  seea  a  little  withiu  the  focus. 


Fig.  57. 


Blood-globules 
of  coin. 


adhering   together,  like    rolls 


placed  under  the  microscope, 
the  blood-globules,  after  a 
fluctuating  movement  of 
short  duration,  very  often 
arrano;e  themselves  in  slip;ht- 
ly  curved  rows  or  chains,  in 
which  they  adhere  to  each 
other  by  their  flat  surfaces, 
presenting  an  appearance 
which  has  been  aptly  com- 
pared with  that  of  rolls  of 
coin.  This  is  probably  owing 
merely  to  the  coagulation  of 
the  blood,  which  takes  place 
very  rapidly  when  it  is  spread 


BLOOD-GLOBULES.  181 

out  in  thin  layers  and  in  contact  with  glass  surfaces;  and  which, 
by  compressing  the  globules,  forces  them  into  such  a  position  that 
they  may  occupy  the  least  possible  space.  This  position  is  evi- 
dently that  in  which  they  are  applied  to  each  other  by  their  flat 
surfaces,  as  above  described. 

The  color  of  the  blood-globules,  when  viewed  by  transmitted 
light  and  spread  out  in  a  thin  layer,  is  a  light  amber  or  pale  yellow. 
It  is,  on  the  contrary,  deep  red  when  they  are  seen  by  reflected 
light,  or  piled  together  in  comparatively  thick  layers.  When  viewed 
singly,  they  are  so  transparent  that  the  outlines  of  those  lying  under- 
neath can  be  easily  seen,  showing  through  the  substance  of  the 
superjacent  globules.  Their  consistency  is  peculiar.  They  are  not 
solid  bodies,  as  they  have  been  sometimes  inadvertently  described ; 
but  on  the  contrary  have  a  consistency  which  is  very  nearly  fluid. 
They  are  in  consequence  exceedingly  flexible,  and  easily  elongated, 
bent,  or  otherwise  distorted  by  accidental  pressure,  or  in  passing 
through  the  narrow  currents  of  fluid  which  often  establish  them- 
selves accidentally  in  a  drop  of  blood  under  microscopic  examina- 
tion. This  distortion,  however,  is  only  temporary,  and  the  globules 
regain  their  original  shape,  as  soon  as  the  accidental  pressure  is 
taken  off.  The  peculiar  flexibility  and  elasticity  thus  noticed  are 
characteristic  of  the  red  globules  of  the  blood,  and  may  always 
serve  to  distinguish  them  from  any  other  free  cells  which  may  be 
found  in  the  animal  tissues  or  fluids. 

In  structure  the  blood-globules  are  homogeneous.  They  have 
been  sometimes  erroneously  described  as  consisting  of  a  closed 
vesicle  or  cell-wall,  containing  in  its  cavity  some  fluid  or  serai-fluid 
substance  of  a  different  character  from  that  composing  the  wall  of 
the  vesicle  itself.  No  such  structure,  however,  is  really  to  be  seen 
in  them.  Each  blood-globule  consists  of  a  mass  of  organized  ani- 
mal substance,  perfectly  or  nearly  homogeneous  in  appearance,  and 
of  the  same  color,  consistency  and  composition  throughout.  In 
some  of  the  lower  animals  (birds,  reptiles,  fish)  it  contains  also 
a  granular  nucleus,  imbedded  in  the  substance  of  the  globule ;  but 
in  no  instance  is  there  any  distinction  to  be  made  out  between  an 
external  cell-wall  and  an  internal  cavity. 

The  appearance  of  the  blood-globules  is  altered  by  the  addition 
of  various  foreign  substances.  If  water  be  added,  so  as  to  dilute 
the  plasma,  the  globules  absorb  it  by  imbibition,  swell,  lose  their 
double  central  concavity  and  become  paler.  If  a  larger  quantity 
of  water  be  added,  they  finally  dissolve  and  disappear  altogether. 


182 


THE    BLOOD. 


B  L  0  0  D  -  G  L  O  B  U  L  E  S  , 

water. 


swollen  by  the  imbibitiou  of 


When  a  moderate  quantity  of  water  is  mixed  with  the  blood,  the 
edges   of  the  globules,  being  thicker  than  the   central  portions, 

and   absorbing  water   more 
^ig-  5S-  abundantly,  become  turgid, 

and  encroach  gradually  upon 
the  central  part.  (Fig.  58.) 
It  is  very  common  to  see 
the  central  depression,  under 
these  circumstances,  disap- 
pear on  one  side  before  it 
is  lost  on  the  other,  so  that 
the  globule,  as  it  swells  up, 
curls  over  towards  one  side, 
and  assumes  a  peculiar  cup- 
shaped  form  (a).  This  form 
may  often  be  seen  in  blood- 
globules  that  have  been 
soaking  for  some  time  in  the 
urine,  or  in  any  other  animal 
fluid  of  a  less  density  than  the  plasma  of  the  blood.  Dilute  acetic 
acid  dissolves  the  blood-globules  more  promptly  than  water,  and 
solutions  of  the  caustic  alkalies  more  promptly  still. 

If  a  drop  of  blood  be  allowed  partially  to  evaporate  while  under 

the  microscope,  the  globules 
Fig-  59.  near  the  edges  of  the  prepa- 

ration often  diminish  in  size, 
and  at  the  same  time  present 
a  shrunken  and  crenated  ap- 
pearance, as  if  minute  gran- 
ules were  projecting  from 
their  surfaces  (Fig.  59);  an 
effect  apparently  produced 
by  the  evaporation  of  part 
of  their  watery  ingredients. 
For  some  unexplained  rea- 
son, however,  a  similar  dis- 
tortion is  often  produced  in 
some  of  the  globules  by  the 
addition  of  certain  other  ani- 
mal fluids,  as  for  example  the 
saliva;  and  a  few  can  even  be  seen  in  this  condition  after  the 
addition  of  pure  water. 


Bloob-globdles 
crenated. 


shrunken,  with  their  margins 


BLOOD-GLOBULES.  183 

The  entire  mass  of  the  blood-globules,  in  proportion  to  the  rest 
of  the  circulating  fluid,  can  only  be  approximately  measured  by 
the  eve  in  a  microscopic  examination.  In  ordinary  analyses  the 
globules  are  usually  estimated  as  amounting  to  about  fifteen  per 
cent.,  by  weight,  of  the  entire  blood.  This  estimate,  however,  refers, 
properly  speaking,  not  to  the  globules  themselves,  but  only  to  their 
dry  residue,  after  the  water  which  they  contain  has  been  lost  by 
evaporation.  It  is  easily  seen,  by  examination  with  the  microscope, 
that  the  globules,  in  their  natural  semi-fluid  condition,  are  really 
much  more  abundant  than  this,  and  constitute  fully  one-half  the 
entire  mass  of  the  blood;  that  is,  the  intercellular  fluid,  or  plasma,  is 
not  more  abundant  than  the  globules  themselves  which  are  sus- 
pended in  it.  When  separated  from  the  other  ingredients  of  the 
blood  and  examined  by  themselves,  the  globules  are  found,  ac- 
cording to  Lehmann,  to  present  the  following  composition  : — 

CoMPosiTiox  OF  THE  Blocd-Globules  IN  1000  Parts. 

Water 688.00 

Globnline    ...........     282.22 

Hsematine 16.75 

Fatty  substances  .........         2.31 

Undetermined  (extractive)  matters      .         .         .         .         .         .         2.60 

Chloride  of  sodium      ....... 

"  potassium  ...... 

Phosphates  of  soda  and  potass    ..... 

Sulphates         "  "  ...... 

Phosphate  of  lime       ....... 

"  magnesia        .         .         .         .         .         . 


1-  8.12 


1000.00 

The  most  important  of  these  ingredients  is  the  glohuline.  This 
is  an  organic  substance,  nearly  fluid  in  its  natural  condition  by 
union  with  water,  and  constituting  the  greater  part  of  the  mass  of 
the  blood-globules.  It  is  soluble  in  water,  but  insoluble  in  the 
plasma  of  the  blood,  owing  to  the  presence  in  that  fluid  of  albumen 
and  saline  matters.  If  the  blood  be  largely  diluted,  however,  the 
globuline  is  dissolved,  as  already  mentioned,  and  the  blood-globules 
are  destroyed.  Globuline  coagulates  by  heat;  but,  according  to 
Eobin  and  Yerdeil,  only  becomes  opalescent  at  160°,  and  requires 
for  its  complete  coagulation  a  temperature  of  200°  F. 

The  hcematme  is  the  coloring  matter  of  the  globules.  It  is,  like 
globuline,  an  organic  substance,  but  is  present  in  much  smaller  quan- 
tity than  the  latter.  It  is  not  contained  in  the  form  of  a  powder, 
mechanically  deposited  in  the  globuline,  but  the  two  substances  are 


184 


THE    BLOOD. 


intimately  mingled  throughout  the  mass  of  the  blood-globule,  just 
as  the  fibrin  and  albumen  are  mingled  in  the  plasma.  Heematine 
contains,  like  the  other  coloring  matters,  a  small  proportion  of  iron. 
This  iron  has  been  supposed  to  exist  under  the  form  of  an  oxide ; 
and  to  contribute  directly  in  this  way  to  the  red  color  of  the  sub- 
stance in  question.  But  it  is  now  ascertained  that  although  the 
iron  is  found  in  an  oxidized  form  in  the  ashes  of  the  blood-globules 
after  they  have  been  destroyed  by  heat,  its  oxidation  probably  takes 
place  during  the  process  of  incineration.  So  far  as  we  know,  there- 
fore, the  iron  exists  originally  in  the  h^ematine  as  an  ultimate 
element,  directly  combined  with  the  other  ingredients  of  this  sub- 
stance, in  the  same  manner  as  the  carbon,  the  hydrogen,  or  the 
nitrogen. 

The  blood-globules  of  all  the  warm  blooded  quadrupeds,  with 
the  exception  of  the  family  of  the  caraelidse,  resemble  those  of  the 
human  species  in  shape  and  structure.  They  differ,  however,  some- 
what in  size,  being  usually  rather  smaller  than  in  man.  There  are 
but  two  species  in  which  they  are  known  to  be  larger  than  in  man, 
viz.,  the  Indian  elephant,  in  which  they  are  27^00  of  ^^^  inch,  and 
the  two-toed  sloth  {Bradypus  didactylus),  in  which  they  are  ogVo  of 
an  inch  in  diameter.  In  the  musk  deer  of  Java  they  are  smaller 
than  in  any  other  known  species,  measuring  rather  less  than  yg^oo- 
of  an  inch.  The  following  is  a  list  showing  the  size  of  the  red 
globules  of  the  blood  in  the  principal  mammalian  species,  taken 
from  the  measurements  of  Mr.  Gulliver,' 

Diameter  of  Red  Globules  in  the 


Ape     . 

•        jj'do  of 

an  i 

nch. 

Cat     . 

•       4iV7irOf 

an  inch. 

Horse 

iHUff 

Fox     . 

iiVff 

Ox       . 

4  A  (J 

Wolf  . 

5sW 

Sheep 

ssr'oij 

Elephant     . 

J705 

Goat    . 

B^'oij 

Red  deer 

T(JO-ff_ 

Dog     . 

FsVff 

Musk  deer  . 

•       TSoUS 

In  all  these  instances  the  form  and  general  appearance  of  the 
globules  are  the  same.  The  only  exception  to  this  rule  among  the 
mammalians  is  in  the  family  of  the  camelidas  (camel,  dromedary, 
lama),  in  which  the  globules  present  an  oval  outline  instead  of  a 
circular  one.     In  other  respects  they  resemble  the  foregoing. 

In  the  three  remaining  classes  of  vertebrate  animals,  viz.,  birds, 
reptiles  and  fish,  the  blood-globules  differ  so  much  from  the  above 
that  they  can  be  readily  distinguished  by  microscopic  examination. 


In  works  of  William  Hewson,  Sydenham  edition,  London,  1846,  p.  327. 


BLOOD-GLOBULES. 


185 


Blood-globules  of  Frog. 
seen  edgewise,    h.  White  globule. 


-a.  Blood-globule 


They  are  oval  in  form,  and  contain  a  colorless  granular  nucleus 
imbedded  in  their  substance.     They  are  also  considerably  larger 
than  the  blood-globules  of   the  mammalians,  particularly  in    the 
class  of  reptiles.    In  the  frog 
(Fig.  60)  they  measure  joVu 
of    an   inch    in   their    long 
diameter;  and  in  Menohran- 
chiis,  the  great  water  lizard 
of  the  northern  lakes,  ^^^  of 
an   inch.     In  Proteus  angui- 
nus  they  attain  the  size,  ac- 
cording to  Dr.  Carpenter,'  of 
gi^y  of  an  inch. 

Beside  the  corpuscles  de- 
scribed above,  there  are  glo- 
bules of  another  kind  found 
in  the  blood,  viz.,  the  lokite 
globules.  These  globules  are 
very  much  less  numerous 
than  the  red ;  the  proportion 

between  the  two,  in  human  blood,  being  one  white  to  two  or  three 
hundred  red  globules.  In  reptiles,  the  relative  quantity  of  the 
w^hite  globules  is  greater,  but  they  are  always  considerably  less 
abundant  than  the  red.  They  differ  also  from  the  latter  in  shape, 
size,  color  and  consistency.  They  are  globular  in  form,  white  or 
colorless,  and  instead  of  being  homogeneous  like  the  others,  their 
substance  is  filled  everywhere  with  minute  dark  molecules  which 
give  them  a  finely  granular  appearance.  (Fig.  54,  c.)  In  size  they 
are  considerably  larger  than  the  red  globules,  being  about  05V0  of 
an  inch  in  diameter.  They  are  also  more  consistent  than  the  others, 
and  do  not  so  easily  glide  along  in  the  minute  currents  of  a  drop  of 
blood  under  examination,  but  adhere  readily  to  the  surfaces  of  the 
glass.  If  treated  with  dilute  acetic  acid,  they  swell  up  and  become 
smooth  and  circular  in  outline ;  and  at  the  same  time  a  separation 
or  partial  coagulation  seems  to  take  place  in  the  substance  of  which 
they  are  composed,  so  that  an  irregular  collection  of  granular 
matter  shows  itself  in  their  interior,  becoming  more  divided  and 
broken  up  as  the  action  of  the  acetic  acid  upon  the  globule  is 
longer  continued.  (Fig.  61.)     This  collection  of  granular  matter 


The  Microscope  and  its  Revelations,  Philadelphia  edition,  p.  600. 


186 


THE    BLOOD. 


often  assumes  a  curved  or  crescentic  form,  as  at  «,  and  sometimes 
various  other  irregular  shapes.     It  does  not  indicate  the  existence 

of  a  nucleus   in    the  white 


Fig.  61. 


Whtte  Globhles  of  the  Blood;  altered  by 
dilute  acetic  acid- 


Ill 

globule,  but  is  merely  an 
appearance  produced  by  the 
coagulating  and  disintegrat- 
ing action  of  acetic  acid  upon 
the  substance  of  which  it  is 
composed. 

The  chemical  constitution 
of  the  white  globules,  as 
distinguished  from  the  red, 
has  never  been  determined ; 
owing  to  the  small  quantity 
in  which  they  occur,  and  the 
difficulty  of  separating  them 
from  the  others  for  purposes 
of  analysis. 

The  two  kinds  of  blood- 
globules,  white  and  red,  are  to  be  regarded  as  distinct  and  inde- 
pendent anatomical  forms.  It  has  been  sometimes  supposed  that 
the  white  globules  were  converted,  by  a  gradual  transformation, 
into  the  red.  There  is,  however,  no  direct  evidence  of  this ;  as 
the  transformation  has  never  been  seen  to  take  place,  either  in  the 
human  subject  or  in  the  mammalia,  nor  even  its  intermediate 
stages  satisfactorily  observed.  When,  therefore,  in  default  of  any 
such  direct  evidence,  we  are  reduced  to  the  surmise  which  has 
been  adopted  by  some  authors,  viz.,  that  the  change  "  takes  place 
too  rapidly  to  be  detected  by  our  means  of  observation,"^  it  must 
be  acknowledged  that  the  above  opinion  has  no  solid  founda- 
tion. It  has  been  stated  by  some  authors  (Kcilliker,  Gerlach) 
that  in  the  blood  of  the  batrachian  reptiles  there  are  to  be  seen 
certain  bodies  intermediate  in  appearance  between  the  white  and 
the  red  globules,  and  which  represent  different  stages  of  transi- 
tion from  one  form  to  the  other;  but  this  is  not  a  fact  which  is 
generally  acknowledged.  "We  have  repeatedly  examined,  with 
reference  to  this  point,  the  fresh  blood  of  the  frog,  as  well  as  that 
of  the  menobranchus,  in  which  the  large  size  of  the  globules 
would  give  every  opportunity  for  detecting  any  such  changes,  did 


'  Kolliker,  Handbuch  der  Gewebelelire,  Leipzig,  1852,  p.  582. 


BLOOD-GLOBULES. — PLASMA.  187 

they  really  exist;  and  it  is  our  unavoidable  conclusion  from  these 
observations,  that  there  is  no  good  evidence,  even  in  the  blood  of 
reptiles,  of  any  sucli  transformation  taking  place.  There  is  simply, 
as  in  human  blood,  a  certain  variation  in  size  and  opacit}'-  among 
the  red  globules;  but  no  such  connection  with,  or  resemblance  to, 
the  white  globules  as  to  indicate  a  passage  from  one  form  to  the 
other.  The  red  and  white  globules  are  therefore  to  be  regarded  as 
distinct  and  independent  anatomical  elements.  They  are  mingled 
together  in  the  blood  just  as  capillary  bloodvessels  and  nerves  are 
mino-led  in  areolar  tissue;  but  there  is  no  other  connection  between 
them,  so  far  as  their  formation  is  concerned,  than  that  of  juxtapo- 
sition. 

Neither  is  it  at  all  probable  that  the  red  globules  are  produced  or 
destroyed  in  any  particular  part  of  the  body.  One  ground  for  the 
belief  that  these  bodies  were  produced  by  a  metamorphosis  of  the 
white  globules  was  a  supposition  that  they  were  continually  and 
rapidly  destroyed  somewhere  in  the  circulation ;  and  as  this  loss 
must  be  as  rapidly  counterbalanced  by  the  formation  of  new  glo- 
bules, and  as  no  other  probable  source  of  their  reproduction  ap- 
peared, they  were  supposed  to  be  produced  by  transformation  of 
the  white  globules.  But  there  is  no  reason  for  believing  that  the 
red  globules  of  the  blood  are  any  less  permanent,  as  anatomical 
forms,  than  tbe  muscular  fibres  or  the  nervous  filaments.  They 
undergo,  it  is  true,  like  all  the  constituent  parts  of  the  body,  a 
constant  interstitial  metamorphosis.  They  absorb  incessantly  nu- 
tritious materials  from  the  blood,  and  give  up  to  the  circulating 
fluid,  at  the  same  time,  other  substances  which  result  from  their 
internal  waste  and  disintegration.  But  they  do  not,  so  far  as  we 
know,  perish  bodily  in  any  part  of  the  circulation.  It  is  not  the 
anatomical  forms^  anywhere,  which  undergo  destruction  and  reno- 
vation in  the  nutritive  process;  but  only  the  proximate  principles  of 
tvhich  they  are  composed.  The  effect  of  this  interstitial  nutrition, 
therefore,  in  the  blood-globules  as  in  the  various  solid  tissues,  is 
merely  to  maintain  them  in  a  natural  and  healthy  condition  of 
integrity. 


PLASMA. 

The  plasma  of  the  blood,  according  to  Lehmann,  has  the  follow- 
ing constitution: — 


188 


THE    BLOOD. 


Composition  of  the  Plasma  in  1000  Parts. 

Water •.         .         .         .     902.90 

Fibrin 4.05 

Albumen 78.84 

Fatty  matters 1.72 

Undetermined  (extractive)  matters      .         .         .         .         .         .         3.94 

Chloride  of  sodium      ........ 

"  potassium         ....... 

Phosphates  of  soda  and  potass     ...... 

Sulphates         "  "  

Phosphate  of  lime        ........ 

"  magnesia        ....... 


8.55 


1000.00 


The  above  ingredients  are  all  intimately  mingled  in  the  blood- 
plasma,  in  a  fluid  form,  by  mutual  solution;  but  they  may  be 
separated  from  each  other  for  examination  by  appropriate  means. 
The  two  ingredients  belonging  to  the  class  of  organic  substances 
are  the  fibrin  and  the  albumen. 

The  fibrin^  though  present  in  small  quantity,  is  evidently  an 
important  element  in  the  constitution  of  the  blood.  It  may  be  ob- 
tained in  a  tolerably  pure  form  by  gently  stirring  freshly  drawn 
blood  with  a  glass  rod  or  a  bundle  of  twigs;  upon  which  the 
fibrin  coagulates,  and  adheres  to  the  twigs  in  the  form  of  slender 
threads  and  flakes.  The  fibrin,  thus  coagulated,  is  at  first  colored 
red  by  the  haematine  of  the  blood  globules  entangled  in  it ;  but 
it  may  be  washed  colorless  by  a  few  hours'  soaking  in  running 

water.     The  fibrin  then  pre- 


Fig.  62. 


Coagulated  Fibrin,  sliowing  its  fibrillated  con- 
dition. 


sents  itself  under  the  form 
of  nearly  white  threads  and 
flakes,  having  a  semi-solid 
consistency,  and  a  consider- 
able degree  of  elasticity. 

The  coagulation  of  fibrin 
takes  place  in  a  peculiar 
manner.  It  does  not  solidify 
in  a  perfectly  homogeneous 
mass;  but  if  examined  by  the 
microscope  in  thin  layers  it 
is  seen  to  have  a  fibroid  or 
filamentous  texture.  In  this 
condition  it  is  said  to  be 
"  fibrillated."  (Fig.  62.)    The 


PLASMA.  189 

filaments  of  which  it  is  composed  are  colorless  and  elastic,  and 
when  isolated  are  seen  to  be  exceedingly  minute,  being  not  more 
than  4o^^^Tj  or  6ven  ^^-J-^xr  of  ^^  i^ich  in  diameter.  They  are  in 
part  arranged  so  as  to  lie  parallel  with  each  other;  but  are  more 
generally  interlaced  in  a  kind  of  irregular  network,  crossing  each 
other  in  every  direction.  On  the  addition  of  dilute  acetic  acid,  they 
swell  up  and  fuse  together  into  a  homogeneous  mass,  but  do  not  dis- 
solve. They  are  often  interspersed  everywhere  with  minute  granu- 
lar molecules,  which  render  their  outlines  more  or  less  obscure. 

Once  coagulated,  fibrin  is  insoluble  in  water  and  can  only  be 
again  liquefied  by  the  action  of  an  alkaline  or  strongly  saline 
solution,  or  by  prolonged  boiling  at  a  very  high  temperature. 
These  agents,  however,  produce  a  complete  alteration  in  the  proper- 
ties of  the  fibrin,  and  after  being  subjected  to  them  it  is  no  longer 
the  same  substance  as  before. 

The  quantity  of  fibrin  in  the  blood  varies  in  different  parts  of  the 
body.  According  to  the  observations  of  various  writers,'  there  is 
more  fibrin  generally  in  arterial  than  in  venous  blood.  The  blood 
of  the  veins  near  the  heart,  again,  contains  a  smaller  proportion  of 
fibrin  than  those  at  a  distance.  The  blood  of  the  portal  vein  con- 
tains less  than  that  of  the  jugular  ;  and  that  of  the  hepatic  vein  less 
than  that  of  the  portal. 

The  albumen  is  undoubtedly  the  most  important  ingredient  of  the 
plasma,  judging  both  from  its  nature  and  the  abundance  in  which 
it  occurs.  It  coagulates  at  once  on  being  heated  to  160°  P.,  or  by 
contact  with  alcohol,  the  mineral  acids,  the  metallic  salts,  or  with 
ferrocyanide  of  potassium  in  an  acidulated  solution.  It  exists 
naturally  in  the  plasma  in  a  fluid  form  by  reason  of  its  union  with 
water.  The  greater  part  of  the  water  of  the  plasma,  in  fact,  is  in 
union  with  the  albumen ;  and  when  the  albumen  coagulates,  the 
water  remains  united  with  it,  and  assumes  at  the  same  time  the 
solid  form.  If  the  plasma  of  the  blood,  therefore,  after  the  removal 
of  the  fibrin,  be  exposed  to  the  temperature  of  160°  F.,  it  solidifies 
almost  completely ;  so  that  only  a  few  drops  of  water  remain  that 
can  be  drained  away  from  the  coagulated  mass.  The  phosphates 
of  lime  and  magnesia  are  also  held  in  solution  principally  by  the 
albumen,  and  are  retained  by  it  in  coagulation. 

The  fatty  matters  exist  in  the  blood  mostly  in  a  saponified  form, 
excepting  soon  after  the  digestion  of  food  rich  in  fat.  At  that 
period,  as  we  have  already  mentioned,  the  emulsioned  fat  finds  its  way 

'  Robin  and  Verdeil,  op.  cit.,  vol.  ii.  p.  202. 


190  THE    BLOOD. 

into  the  blood,  and  circulates  for  a  time  unchanged.  Afterward  it 
disappears  as  free  fat,  and  remains  partly  in  the  saponified  condition. 

The  saline  ingredients  of  the  plasma  are  of  the  same  nature  with 
those  existing  in  the  globules.  The  chlorides  of  sodium  and 
potassium,  and  the  phosphates  of  soda  and  potass  are  the  most 
abundant  in  both,  while  the  sulphates  are  present  only  in  minute 
quantity.  The  proportions  in  which  the  various  salts  are  present 
are  very  different,  according  to  Lehmann,^  in  the  blood-globules 
and  in  the  plasma.  Chloride  of  potassium  is  most  abundant 
in  the  globules,  chloride  of  sodium  in  the  plasma.  The  phos- 
phates of  soda  and  potass  are  more  abundant  in  the  globules  than 
in  the  plasma.  On  the  other  hand,  the  phosphates  of  lime  and 
magnesia  are  more  abundant  in  the  plasma  than  in  the  globules. 

The  substances  known  under  the  name  of  extractive  matters  consist 
of  a  mixture  of  different  ingredients,  belonging  mostly  to  the  class 
of  organic  substances,  which  have  not  yet  been  separated  in  a  state 
of  sufficient  purity  to  admit  of  their  being  thoroughly  examined 
and  distinguished  from  each  other.  They  do  not  exist  in  great 
abundance,  but  are  -undoubtedly  of  considerable  importance  in  the 
constitution  of  the  blood.  Beside  the  substances  enumerated  in  the 
above  list,  there  are  still  others  which  occur  in  small  quantity  as 
ingredients  of  the  blood.  Among  the  most  important  are  the 
alkaline  carbonates,  which  are  held  in  solution  in  the  serum.  It  has 
■already  been  mentioned  that  while  the  phosphates  are  most 
abundant  in  the  blood  of  the  carnivora,  the  carbonates  are  most 
abundant  in  that  of  the  herbivora.  Thus  Lehmann^  found  car- 
bonate of  soda  in  the  blood  of  the  ox  in  the  proportion  of  1.628  per 
thousand  parts.  There  are  also  to  be  found,  in  solution  in  the 
blood,  urea,  urate  of  soda,  creatine,  creatinine,  sugar,  &c.;  all  of  them 
ci-ystallizable  substances  derived  from  the  transformation  of  other 
ingredients  of  the  blood,  or  of  the  tissues  through  which  it  circu- 
lates. The  relative  quantity,  however,  of  these  substances  is  very 
minute,  and  has  not  yet  been  determined  with  precision. 


COAGULATION  OF  THE  BLOOD. 

A  few  moments  after  the  blood  has  been  withdrawn  from  the 
vessels,  a  remarkable  phenomenon  presents  itself,  viz.,  its  coagula- 
tion or  clotting.     This  process  commences  at  nearly  the  same  time 

'  Op.  cit .  voL  i.  p.  546.  '  Op.  cit.,  vol.  i.  p.  393. 


COAGULATION  OF  THE  BLOOD.  191 

throughout  the  whole  mass  of  the  blood.  The  blood  becomes  first 
somewhat  diminished  in  fluidity,  so  that  it  will  not  run  over  the 
edge  of  the  vessel,  when  slightly  inclined ;  and  its  surface  may  be 
gently  depressed  with  the  end  of  the  finger  or  a  glass  rod.  It  then 
becomes  rapidly  thicker,  and  at  last  solidifies  into  a  uniformly  red, 
opaque,  consistent,  gelatinous  mass,  which  takes  the  form  of  the 
vessel  in  which  the  blood  was  received.  Its  coagulation  is  then 
complete.  The  process  usually  commences,  in  the  human  subject, 
in  about  fifteen  minutes  after  the  blood  has  been  drawn,  and  is 
completed  in  about  twenty  minutes. 

The  coagulation  of  the  blood  is  dependent  entirely  upon  the 
presence  of  the  fibrin.  This  fact  has  been  demonstrated  in  various 
ways.  In  the  first  place,  if  frog's  blood  be  filtered,  so  as  to  separate 
the  globules  and  leave  them  upon  the  filter,  while  the  plasma  is 
allowed  to  run  through,  the  colorless  filtered  fluid  which  contains 
the  fibrin  soon  coagulates ;  while  no  coagulation  takes  place  in  the 
moist  globules  remaining  on  the  filter.  Again,  if  the  freshly  drawn 
blood  be  stirred  with  a  bundle  of  rods,  as  we  have  already  de- 
scribed above,  the  fibrin  coagulates  upon  them  by  itself,  while  the 
rest  of  the  plasma,  mixed  with  the  globules,  remains  perfectly  fluid. 
It  is  the  fibrin,  therefore,  which,  by  its  own  coagulation,  induces 
the  solidification  of  the  entire  blood.  As  the  fibrin  is  uniformly 
distributed  throughout  the  blood,  when  its  coagulation  takes  place 
the  minute  filaments  which  make  their  appearance  in  it  entangle 
in  their  meshes  the  globules  and  the  albuminous  fluids  of  the 
plasma.  A  very  small  quantity  of  fibrin,  therefore,  is  sufficient  to 
entangle  by  its  coagulation  all  the  fluid  and  semi-fluid  parts  of  the 
blood,  and  convert  the  whole  into  a  volumi- 
nous, trembling,  jelly-like  mass,  which  is  Fig.  63. 
known  by  the  name  of  the  "  crassamentum" 
or  "  clot."  (Fig.  63.) 

As  soon  as  the  clot  has  fairly  formed,  it 
begins  to  contract  and  diminish  in  size.  Ex- 
actly how  this  contraction  of  the  clot  is  pro- 
duced, we  are  unable  to  say ;  but  it  is  proba- 
bly a  continuation  of  the  same  process  by 
which  its  solidification  is  at  first  accomplished,  b,^i  „f  ^^^^^^^^  p^^^^. 
or  at  least  one  very  similar  to  it.     As  the     lated  blood,  showing  the 

.  ,•  1        ,1  11  •  n     ■  ^         whole  mass  uniformly  solidi- 

contraction  proceeds,  the  albuminous  fluids     ged. 

begin  to  be  pressed  out  from  the  meshes  in 

which  they  were  entangled.     A  few  isolated  drops  first  appear  on 


192 


THE    BLOOD. 


Fig.  64. 


the  surface  of  the  clot.  These  drops  soon  increase  in  size  and  be- 
come more  numerous.  They  run  together  and  coalesce  with  each 
other,  as  more  and  more  fluid  exudes  from  the  coagulated  mass, 
until  the  whole  surface  of  the  clot  is  covered  with  a  thin  layer  of 
fluid.  The  clot  at  first  adheres  pretty  strongly  to  the  sides  of  the 
vessel  into  which  the  blood  was  drawn ;  but  as  its  contraction  goes 
on,  its  edges  are  separated,  and  the  fluid  continues  to  exude  between 
it  and  the  sides  of  the  vessel.  This  exudation 
continues  for  ten  or  twelve  hours;  the  clot 
growing  constantly  smaller  and  firmer,  and 
the  expressed  fluid  more  and  more  abundant. 
The  globules,  owing  to  their  greater  con- 
sistency, do  not  escape  with  the  albuminous 
fluids,  but  remain  entangled  in  the  fibrinous 
coagulum.  Finally,  at  the  end  of  ten  or 
twelve  hours  the  whole  of  the  blood  has  usu- 
ally separated  into  two  parts,  viz.,  the  clot, 
which  is  a  red,  opaque,  dense  and  resisting, 
semi-solid  mass,  consisting  of  the  fibrin  and 
the  blood-globules;  and  the  serum,  which  is  a 
transparent,  nearly  colorless  fluid,  containing  the  water,  albumen, 
and  saline  matters  of  the  plasma.  (Fig.  64.) 

The  change  of  the  blood  in  coagulation  may  therefore  be  ex- 
pressed as  follows : — 


Bowl  of  Coagulated 
Blood,  after  twelve  hours ; 
showing  the  clot  contracted 
and  floating  iu  the  fluid  serum. 


Before  coagulation  the  blood  consists  of 


1st.  Globules  ;  and  2d.  Plasma — containing 


After  coagulation  it  is  separated  into 


1st.  Clot,  containing  i 


Fibrin  and 
I  Globules ; 


Fibrin, 
Albumen, 
Water, 
Salts. 


(  Albumen, 


and  2d.  Serum,  containing  -^  Water, 
i  Salts. 


The  coagulation  of  the  blood  is  hastened  or  retarded  by  various 
physical  conditions,  which  have  been  studied  with  care  by  various 
observers,  but  more  particularly  by  Kobin  and  Yerdeil.  The  con- 
ditions which  influence  the  rapidity  of  coagulation  are  as  follows  : 
First,  the  rapidity  with  which  the  blood  is  drawn  from  the  vein, 
and  the  size  of  the  orifice  from  which  it  flows.  If  blood  be  drawn 
rapidly,  in  a  full  stream,  from  a  large  orifice,  it  remains  fluid  for  a 
comparatively  long  time ;  if  it  be  drawn  slowly,  from  a  narrow 


COAGULATION  OF  THE  BLOOD.  193 

orifice,  it  coagulates  quickly.  Tlius  it  usually  happens  that  in  the 
operation  of  venesection,  the  blood  drawn  immediately  after  the 
opening  of  the  vein  runs  freely  and  coagulates  slowly;  while  that 
which  is  drawn  toward  the  end  of  the  operation,  when  the  tension 
of  the  veins  has  been  relieved  and  the  blood  trickles  slowly  from 
the  wound,  coagulates  quickly.  Secondly,  the  shape  of  the  vessel 
into  which  the  blood  is  received  and  the  condition  of  its  internal 
surface.  The  greater  the  extent  of  surface  over  which  the  blood 
comes  in  contact  with  the  vessel,  the  more  is  its  coagulation 
hastened.  Thus,  if  the  blood  be  allowed  to  flow  into  a  tall,  narrow, 
cylindrical  vessel,  or  into  a  shallow  plate,  it  coagulates  more  rapidly 
than  if  it  be  received  into  a  hemispherical  bowl,  in  which  the  ex- 
tent of  surface  is  less,  in  proportion  to  the  entire  quantity  of  blood 
which  it  contains.  For  the  same  reason,  coagulation  takes  place 
more  rapidly  in  a  vessel  with  a  roughened  internal  surface,  than  in 
one  which  is  smooth  and  polished.  The  blood  coagulates  most 
rapidly  when  spread  out  in  thin  layers,  and  entangled  among  the 
fibres  of  cloth  or  sponges.  For  the  same  reason,  also,  hemorrhage 
continues  longer  from  an  incised  wound  than  from  a  lacerated  one; 
because  the  blood,  in  flowing  over  the  ragged  edges  of  the  lacer- 
ated bloodvessels  and  tissues,  solidifies  upon  them  readily,  and  thus 
blocks  up  the  wound. 

In  all  these  cases,  there  is  an  inverse  relation  between  the  rapidity 
of  coagulation  and  the  firmness  of  the  clot.  When  coagulation 
takes  place  slowly,  the  clot  afterward  becomes  small  and  dense,  and 
the  serum  is  abundant.  When  coagulation  is  rapid,  there  is  but 
little  contraction  of  the  coagulum,  an  imperfect  separation  of  the 
serum,  and  the  clot  remains  large,  soft  and  gelatinous. 

It  is  well  known  to  practical  physicians  that  a  similar  relation 
exists  when  the  coagulation  of  the  blood  is  hastened  or  retarded  by 
disease.  In  cases  of -lingering  and  exhausting  illness,  or  in  diseases 
of  a  typhoid  or  exanthematous  character,  with  much  depression  of 
the  vital  powers,  the  blood  coagulates  rapidly  and  the  clot  remains 
soft.  In  cases  of  active  inflammatory  disease,  as  pleurisy  or 
pneumonia,  occurring  in  previously  healthy  subjects,  the  blood 
coagulates  slowly,  and  the  clot  becomes  very  firm.  In  every 
instance,  the  blood  which  has  coagulated  liquefies  again  at  the 
commencement  of  putrefaction. 

The  coagulation  of  the  fibrin  is  not  a  commencement  of  organization. 
The  filaments  already  described,  which  show  themselves  in  the  clot 
(Fig.  62),  are  not,  properly  speaking,  organized  fibres,  and  are  en- 
13 


194  THE    BLOOD. 

tirely  different  in  their  character  from  the  fibres  of  areolar  tissue,  or 
any  other  normal  anatomical  elements.  They  are  simply  the  ultimate 
form  which  fibrin  assumes  in  coagulating,  just  as  albumen  takes  the 
form  of  granules  under  the  same  circumstances.  The  coagulation 
of  fibrin  does  not  differ  in  character  from  that  of  any  other  organic 
substance ;  it  merely  difi'ers  in  the  physical  conditions  which  give 
rise  to  it.  All  the  coagulable  organic  substances  are  naturally  fluid, 
and  coagulate  only  when  they  are  placed  under  certain  unusual  con- 
ditions. But  the  particular  conditions  necessary  for  coagulation 
vary  with  the  different  organic  substances.  Thus  albumen  coagu- 
lates by  the  application  of  heat.  Casein,  which  is  not  affected  by 
heat,  coagulates  by  contact  with  an  acid  body.  Pancreatine,  again, 
is  coagulated  by  contact  with  sulphate  of  magnesia,  which  has  no 
efieet  on  albumen.  So  fibrin,  which  is  naturally  fluid,  and  which 
remains  fluid  so  long  as  it  is  circulating  in  the  vessels,  coagulates 
when  it  is  withdrawn  from  them  and  brought  in  contact  with 
unnatural  surfaces.  Its  coagulation,  therefore,  is  no  more  "  sponta- 
neous," properly  speaking,  than  that  of  any  other  organic  substance. 
Still  less  does  it  indicate  anything  like  organization,  or  even  a 
commencement  of  it.  On  the  contrary,  in  the  natural  processes  of 
nutrition,  fibrin  is  assimilated  by  the  tissues  and  takes  part  in  their 
organization,  only  when  it  is  absorbed  by  them  from  the  blood- 
vessels in  a  fluid  form.  As  soon  as  it  is  once  coagulated  by  any 
means,  it  passes  into  an  unnatural  condition,  and  must  be  again 
liquefied  and  absorbed  into  the  blood  before  it  can  be  assimilated. 

As  the  fibrin,  therefore,  is  maintained  in  its  natural  condition  of 
fluidity  by  the  movement  of  the  circulating  blood  in  the  interior  of 
the  vessels,  anything  which  interferes  with  this  circulation  will 
induce  its  coagulation.  If  a  ligature  be  placed  upon  an  artery  in 
the  living  subject,  the  blood  which  stagnates  above  the  ligature 
coagulates  just  as  it  would  do  if  entirely  removed  from  the  circula- 
tion. If  the  vessel  be  ruptured  or  lacerated,  the  blood  which 
escapes  from  it  into  the  areolar  tissue  coagulates,  because  here  also 
it  is  withdrawn  from  the  circulation.  It  coagulates  also  in  the 
interior  of  the  vessels  after  death  owing  to  the  same  cause,  viz : 
stoppage  of  the  circulation.  During  the  last  moments  of  life,  when 
the  flow  of  blood  through  the  cavities  of  the  heart  is  impeded,  the 
fibrin  often  coagulates,  in  greater  or  less  abundance,  upon  the 
moving  chordss  tendineas  and  the  edges  of  the  valves,  just  as  it 
would  do  if  withdrawn  from  the  body  and  stirred  with  a  bundle 
of  twigs.     In  every  instance,  the  coagulation  of  the  fibrin  is  a 


COAGULATION    OF    THE    BLOOD. 


195 


Vertical    section    of   a.  R  e- 

CENT    COAGCLCM,     showing 

the    greater    accumulation    of 
blood-globules  at  the  bottom. 


morbid  phenomenon,  dependent  on  the  cessation  or  disturbance  of 
the  circulation. 

If  the  blood  be  allowed  to  coagulate  in  a  bowl,  and  the  clot  be 
then  divided  by  a  vertical  section,  it  will 
be  seen  that  its  lower  portion  is  softer  and 
of  a  deeper  red  than  the  upper.  (Fig.  65.) 
This  is  because  the  globules,  which  are  of 
greater  specific  gravity  than  the  plasma,  sink 
toward  the  bottom  of  the  vessel  before  coagu- 
lation takes  place,  and  accumulate  in  the 
lower  portion  of  the  blood.  This  deposit  of 
the  globules,  however,  is  only  partial;  be- 
cause they  are  soon  fixed  and  entangled  by 
the  solid  mass  of  the  coagulum,  and  thus 
retained  in  the  position  in  which  they  hap- 
pened to  be  at  the  moment  that  coagulation  occurred. 

If  the  coagulation,  however,  be  delayed  longer  than  usual,  or  if 
the  globules  sink  more  rapidly  than  is  customary,  they  will  have 
time  to  subside  entirely  from  the  upper  portion  of  the  blood, 
leaving  a  layer  at  the  surface  which  is  composed  of  plasma  alone. 
When  coagulation  then  takes  place,  this  upper  portion  solidifies 
at  the  same  time  with  the  rest,  and  the  clot  then  presents  two  dif- 
ferent portions,  viz.,  a  lower  portion  of  a  dark  red  color,  in  which 
the  globules  are  accumulated,  and  an  upper  portion  from  which  the 
globules  have  subsided,  and  which  is  of  a  grayish  white  color  and 
partially  transparent.  This  whitish  layer  on  the  surface  of  the  clot 
is  termed  the  "  buffy  coat ;"  and  the  blood  presenting  it  is  said  to 
be  "  buffed."  It  is  an  appearance  which  often  presents  itself  in 
cases  of  acute  inflammatory  disease,  in  which  the  coagulation  of  the 
blood  is  unusually  retarded. 

When  a  clot  with  a  buffy  coat  begins  to 
contract,  the  contraction  takes  place  perfectly 
well  in  its  upper  portion,  but  in  the  lower 
part  it  is  impeded  by  the  presence  of  the 
globules  which  have  accumulated  in  large 
quantity  at  the  bottom  of  the  clot.  While 
the  lower  part  of  the  coagulum,  therefore, 
remains  voluminous,  and  hardly  separates 
from  the  sides  of  the  vessel,  its  upper  color- 
less portion  diminishes  very  much  in  size ; 
and  as  its  edges  separate  from  the  sides  of  the  vessel,  they  curl  over 


Bowl        of       CoAOtlLATED 

Blood,     showing    the     clot 
buffed  and  cupped. 


196  THE    BLOOD. 

toward  each  other,  so  that  the  upper  surface  of  the  clot  becomes 
more  or  less  excavated  or  cup-shaped.  (Fig.  66.)  The  blood  is  then 
said  to  be  "  buffed  and  cupped."  These  appearances  do  not  present 
themselves  under  ordinary  conditions,  but  only  when  the  blood  has 
become  altered  by  disease. 

The  entire  quantity  of  blood  existing  in  the  body  has  never  been 
very  accurately  ascertained.  It  is  not  possible  to  extract  the  whole 
of  it  by  opening  the  large  vessels,  since  a  certain  portion  will  always 
remain  in  the  cavities  of  the  heart,  in  the  veins,  and  in  the  capil- 
laries of  the  head  and  abdominal  organs.  The  other  methods 
which  have  been  practised  or  proposed  from  time  to  time  are  all 
liable  to  some  practical  objection.  We  have  accordingly  only 
been  able  thus  far  to  ascertain  the  minimum  quantity  of  blood 
existing  in  the  body.  Weber  and  Lehmann^  ascertained  as  nearly 
as  possible  the  quantity  of  blood  in  two  criminals  who  suflered 
death  by  decapitation ;  in  both  of  which  cases  they  obtained  essen- 
tially similar  results.  The  body  weighed  before  decapitation  133 
pounds  avoirdupois.  The  blood  which  escaped  from  the  vessels  at 
the  time  of  decapitation  amounted  to  12.27  pounds.  In  order  to 
estimate  the  quantity  of  blood  which  remained  in  the  vessels,  the 
experimenters  then  injected  the  arteries  of  the  head  and  trunk  with 
water,  collected  the  watery  fluid  as  it  escaped  from  the  veins,  and 
ascertained  how  much  solid  matter  it  held  in  solution.  This 
amounted  to  477.22  grains,  which  corresponded  to  4.38  pounds  of 
blood.     The  result  of  the  experiment  is  therefore  as  follows : — 

Blood  which  escaped  from  the  vessels     .         .         .         .         .12.27  pounds. 
"  remained  in  the  body  .....      4.38       " 


Whole  quantity  of  blood  in  the  living  body,  16.65 

The  weight  of  the  blood,  then,  in  proportion  to  the  entire  weight 
of  the  body,  was  as  1  :  8 ;  and  the  body  of  a  healthy  man,  weighing 
140  pounds,  will  therefore  contain  on  the  average  at  least  17J 
pounds  of  blood. 

'  Physiological  Chemistry,  vol.  i.  p.  638. 


RESPIRATION".  197 


CHAPTER   XII. 

RESPIRATION. 

The  blood  as  it  circulates  in  the  arterial  system  has  a  bright 
scarlet  color ;  but  as  it  passes  through  the  capillaries  it  gradually 
becomes  darker,  and  on  its  arrival  in  the  veins  its  color  is  a  deep 
purple,  and  in  some  parts  of  the  body  nearly  black.  There  are, 
therefore,  two  kinds  of  blood  in  the  body  ;  arterial  blood,  which  is 
of  a  bright  color,  and  venous  blood,  which  is  dark.  Now  it  is  found 
that  the  dark-colored  venous  blood,  which  has  been  contaminated 
by  passing  through  the  capillaries,  is  unfit  for  further  circulation. 
It  is  incapable,  in  this  state,  of  supplying  the  organs  with  their 
healthy  stimulus  and  nutrition,  and  has  become,  oh  the  contrary, 
deleterious  and  poisonous.  It  is  accordingly  carried  back  to  the 
heart  by  the  veins,  and  thence  sent  to  the  lungs,  where  it  is  recon- 
verted into  arterial  blood.  The  process  by  which  the  venous  blood 
is  thus  arterialized  and  renovated,  is  known  as  the  process  of  re- 
spiration. 

This  process  takes  place  very  actively  in  the  higher  animals,  and 
probably  does  so  to  a  greater  or  less  extent  in  all  animals  without 
exception.  Its  essential  conditions  are  that  the  circulating  fluid 
should  be  exposed  to  the  influence  of  atmospheric  air,  or  of  an 
aerated  fluid ;  that  is,  of  a  fluid  holding  atmospheric  air  or  oxygen 
in  solution.  The  respiratory  apparatus  consists  essentially  of  a 
moist  and  permeable  animal  membrane,  the  respiratory  membrane, 
with  the  bloodvessels  on  one  side  of  it,  and  the  air  or  aerated  fluid 
on  the  other.  The  blood  and  the  air,  consequently,  do  not  come  in 
direct  contact  with  each  other,  but  absorption  and  exhalation  take 
place  from  one  to  the  other  through  the  thin  membrane  which  lies 
between. 

The  special  anatomical  arrangement  of  the  respiratory  apparatus 
differs  in  different  species  of  animals.  In  most  of  those  inhabiting 
the  water,  the  respiratory  organs  have  the  form  of  gills  or  branchice  ; 
that  is,  delicate  filamentous  prolongations  of  some  part  of  the 


198 


EESPIEATION. 


Head   and   Gills   op   Menobranchus. 


integument  or  mucous  membranes,  wlaich  contain  an  abundant 
supply  of  bloodvessels,  and  which  hang  out  freely  into  the  sur- 
rounding water.     In  many  kinds  of  aquatic  lizards,  as,  for  exam- 
ple, in  menohranchus  (Fig.  67), 
'^*  there  are  upon  each  side  of  the 

neck  three  delicate  feathery 
tufts  of  thread-like  prolonga- 
tions from  the  mucous  mem- 
brane of  the  pharynx,  which 
pass  out  through  fissures  in 
the  side  of  the  neck.  Each 
tuft  is  composed  of  a  prin- 
cipal stem,  upon  which  the 
filaments  are  arranged  in  a 
pinnated  form,  like  the  plume  upon  the  shaft  of  a  feather.  Each 
filament,  when  examined  by  itself,  is  seen  to  consist  of  a  thin,  rib- 
bon-shaped, double  fold  of  mucous  membrane,  in  the  interior  of 
which  there  is  a  plentiful  network  of  minute  bloodvessels.  The 
dark  blood,  as  it  comes  into  the  filament  from  the  branchial  artery, 
is  exposed  to  the  influence  of  the  water  in  which  the  filament  is 
bathed,  and  as  it  circulates  through  the  capillary  network  of  the 
gills  is  reconverted  into  arterial  blood.  It  is  then  carried  away  by 
the  branchial  vein,  and  passes  into  the  general  current  of  the  cir- 
culation. The  apparatus  is  further  supplied  with  a  cartilaginous 
framework,  and  a  set  of  muscles  by  which  the  gills  are  gently  waved 
about  in  the  surrounding  water,  and  constantly  brought  into  con- 
tact with  fresh  portions  of  the  aerated  fluid. 

Most  of  the  aquatic  animals  breathe  by  gills  similar  in  all  their 
essential  characters  to  those  described  above.  In  terrestrial  and 
air-breathing  animals,  however,  the  respiratory  apparatus  is  situated 
internally.  In  them,  the  air  is  made  to  penetrate  into  the  interior 
of  the  body,  into  certain  cavities  or  sacs  called  the  lungs,  which 
are  lined  with  a  vascular  mucous  membrane.  In  the  salamanders, 
for  example,  which,  though  aquatic  in  their  habits,  are  air-breathing 
animals,  the  lungs  are  two  long  cylindrical  sacs,  running  nearly  the 
entire  length  of  the  body,  commencing  anteriorly  by  a  communi- 
cation with  the  pharynx,  and  terminating  by  rounded  extremities 
at  the  posterior  part  of  the  abdomen.  These  lungs,  or  air-sacs, 
have  a  smooth  internal  surface;  and  the  blood  which  circulates 
through  their  vessels  is  arterialized  by  exposure  to  the  air  contained 
in  their  cavities.     The  air  is  forced  into  the  lungs  by  a  kind  of 


EESPIEATION. 


199 


Fig.  68. 


swallowing  movement,  and  is  after  a  time  regurgitated  and  dis- 
charged, in  order  to  make  room  for  a  fresh  supply. 

In  the  frog,  tortoise,  serpents,  &c.,  the  structure  of  the  lung  is  a 
little  more  complicated,  since  respiration  is  more  active  in  these 
animals,  and  a  more  perfect  organ  is  requisite  to  accomplish  the 
arterialization  of  the  blood.  In  these  animals,  the  cavity  of  the  lung, 
instead  of  being  simple,  is  divided  by  incomplete  partitions  into  a 
number  of  smaller  cavities  or  "  cells."  The  cells  all  communicate 
with  the  central  pulmonary  cavity;  and  the  partitions,  which  join 
each  other  at  various  angles,  are  all  composed  of  thin,  projecting, 
double  folds  of  the  lining  membrane,  with  bloodvessels  ramifying 
between  them.  (Fig.  68.)  By  this  arrangement, 
the  extent  of  surface  presented  to  the  air  by  the 
pulmonary  membrane  isjnuch  increased,  and  the 
arterialization  of  the  blood  takes  place  with  a 
corresponding  degree  of  rapidity. 

In  the  human  subject,  and  in  all  the  warm- 
blooded quadrupeds,  the  lungs  are  constructed 
on  a  plan  which  is  essentially  similar  to  the 
above,  and  which  differs  from  it  only  in  the 
greater  extent  to  which  the  pulmonary  cavity  is 
subdivided,  and  the  surface  of  the  respiratory 
membrane  increased.  The  respiratory  apparatus 
(Fig.  69)  commences  with  the  larynx,  which 
communicates  with  the  pharynx  at  the  upper  part  of  the  neck. 
Then  follows  the  trachea,  a  membranous  tube  with  cartilaginous 
rings;  which,  upon  its  entrance  into  the  chest,  divides  into  the  right 
and  left  bronchus.  These  again  divide  successively  into  second- 
ary and  tertiary  bronchi;  the  subdivision  continuing,  while  the 
bronchial  tubes  grow  smaller  and  more  numerous,  and  separate 
constantly  from  each  other.  As  they  diminish  in  size,  the  tubes 
grow  more  delicate  in  structure,  and  the  cartilaginous  rings  and 
plates  disappear  from  their  walls.  They  are  finally  reduced,  accord- 
ing to  KoUiker,  to  the  size  of  ^^  of  an  inch  in  diameter ;  and  are 
composed  only  of  a  thin  mucous  membrane,  lined  with  pavement 
epithelium,  which  rests  upon  an  elastic  fibrous  layer.  They  are 
then  known  as  the  "ultimate  bronchial  tubes." 

Each  ultimate  bronchial  tube  terminates  in  a  division  or  islet  of 
the  pulmonary  tissue,  about  y'^  of  an  inch  in  diameter,  which  is 
termed  a  "pulmonary  lobule."  Each  pulmonary  lobule  resembles 
in  its  structure  the  entire  frog's  lung  in  miniature.     It  consists  of  a 


Lung  of  Froo, 
showing  its  internal  sur- 
face 


200 


EESPIEATIOX. 
Fig.  69. 


Fig.  70. 


Human  Larynx,  Trachea,   Bronchi,   and  Lungs;  showing  the  ramification  of  the 
bronchi,  and  the  division  of  the  lungs  into  lobules. 

vascular  membrane  inclosing  a  cavity;  which  cavity  is  divided 
into  a  large  number  of  secondary  compartments  by  thin  septa  or 
partitions,  which  project  from  its  internal  surface.  (Fig.  70.)  These 
secondary  cavities  are  the  "  pulmonary 
cells,"  or  "  vesicles."  Each  vesicle  is  about 
^-g  of  an  inch  in  diameter;  and  is  covered 
on  its  exterior  with  a  close  network  of  ca- 
pillary bloodvessels,  which  dip  down  into 
the  spaces  between  the  adjacent  vesicles,  and 
expose  in  this  way  a  double  surface  to  the 
air  which  is  contained  in  their  cavities. 
Between  the  vesicles,  and  in  the  interstices 
between  the  lobules,  there  is  a  large  quan- 
tity of  yellow  elastic  tissue,  which  gives 
firmness  and  resiliency  to  the  pulmonary 
structure.  The  pulmonary  vesicles,  accord- 
siNGLE  LoBCLE  OF  Hu-    •       ^^  ^j^g   obscrvatious   of  Kdlliker,  are 

MAN  Lung. — a.  Ultimate bron-  °  _  ' 

chiaitube.  h.  Cavity  of  lobule,    lined  cvcrywhcre  with  a  layer  of  pavement 

c,j,c.  Pulmonary  cells,  or  vesi-      epithelium,     COUtinUOUS     with     that     in     the 


RESPIKATORY    MOVEMENTS    OF    THE    CHEST.  201 

ultimate  bronchial  tubes.  The  whole  extent  of  respiratory  sur- 
hce  in  both  lungs  has  been  calculated  by  Lieberkiihn'  at  'fourteen 
hundred  square  feet.  It  is  plainly  impossible  to  make  a  precisely 
accurate  calculation  of  this  extent;  but  there  is  every  reason  to 
believe  that  the  estimate  adopted  by  Lieberkiihn,  regarded  as 
approximative,  is  not  by  any  means  an  exaggerated  one.  The 
great  multiplication  of  the  minute  pulmonary  vesicles,  and  of  the 
partitions  between  them,  must  evidently  increase  to  an  extraor- 
dinary degree  the  extent  of  surface  over  which  the  blood,  spread 
out  in  a  thin  layer,  is  exposed  to  the  action  of  the  air.  These 
anatomical  conditions  are,  therefore,  the  most  favorable  to  its  rapid 
and  complete  arterialization. 

Respiratory  Movements  of  the  Chest. — The  air  which  is  con- 
tained in  the  pulmonary  lobules  and  vesicles  becomes  rapidly  vitiated 
in  the  process  of  respiration,  and  requires  therefore  to  be  expelled 
and  replaced  by  a  fresh  supply.  This  exchange  or  renovation  of 
the  air  is  effected  by  alternate  movements  of  the  chest,  of  expansion 
and  collapse,  which  are  termed  the  "  respiratory  movements  of  the 
chest."  The  expansion  of  the  chest  is  effected  by  two  sets  of  mus- 
cles, viz.,  first,  the  diaphragm,  and,  second,  the  intercostals.  While 
the  diaphragm  is  in  a  state  of  relaxation,  it  has  the  form  of  a  vaulted 
partition  between  the  thorax  and  abdomen,  the  edges  of  which  are 
attached  to  the  inferior  extremity  of  the  sternum,  the  inferior 
costal  cartilages,  the  borders  of  the  lower  ribs  and  the  bodies  of 
the  lumbar  vertebne,  while  its  convexity  rises  high  into  the  cavity 
of  the  chest,  as  far  as  the  level  of  the  fifth  rib.  When  the  fibres 
of  the  diaphragm  contract,  their  curvature  is  necessarily  dimi- 
nished; and  they  approximate  a  straight  line,  exactly  in  proportion 
to  the  extent  of  their  contraction.  Consequently,  the  entire  con- 
vexity of  the  diaphragm  is  diminished  in  the  same  proportion; 
and  it  descends  toward  the  abdomen,  enlarging  the  cavity  of  the 
chest  from  above  downward,  (i^'ig.  71.)  At  the  same  time  the  inter- 
costal muscles  enlarge  it  in  a  lateral  direction.  For  the  ribs,  arti- 
culated behind  with  the  bodies  of  the  vertebrge,  and  joined  in  front 
to  the  sternum  by  the  flexible  and  elastic  costal  cartilages,  are  so 
arranged  that,  in  a  position  of  rest,  their  convexities  look  obliquely 
outward  and  downward.  When  the  movement  of  inspiration  is 
about  to  commence,  the  first  rib  is  fixed  by  the  contraction  of  the 

'  In  Simon's  Chemistry  of  Man,  Philada.  ed.,  1846,  p.  109. 


202 


RESPIRATION. 


Fig.  71. 


scaleni  muscles,  and  the  intercostal  muscles  then  contracting  simul- 
taneously, the  ribs  are  drawn  upward.  In  this  movement,  as  each 
rib  rotates  upon  its  articulation  with  the 
spinal  column  at  one  extremity,  and  with 
the  sternum  at  the  other,  its  convexity  is 
necessarily  carried  outward  at  the  same 
time  that  it  is  drawn  upward,  and  the  pa- 
rietes  of  the  chest  are,  therefore,  expanded 
laterally.  The  sternum  itself  rises  slightly 
with  the  same  movement,  and  enlarges  to 
some  extent  the  antero-posterior  diameter 
of  the  thorax.  By  the  simultaneous  action, 
therefore,  of  the  diaphragm  which  descends, 
and  of  the  intercostal  muscles  which  lift 
the  ribs  and  the  sternum,  the  cavity  of  the 
chest  is  expanded  in  every  direction,  and 
the  air  passes  inward,  through  the  trachea 
and  bronchial  tubes,  by  the  simple  force  of 
aspiration. 

After  the  movement  of  inspiration  is  ac- 
complished, and  the  lungs  are  filled  with 
air,  the  diaphragm  and  intercostal  muscles 
relax,  and  a  movement  of  expiration  takes 
place,  by  which  the  chest  is  partially  col- 
lapsed, and  a  portion  of  the  air  contained 
in  the  pulmonary  cavity  expelled.  The 
movement  of  expiration  is  entirely  a  passive 
one,  and  is  accomplished  by  the  action  of 
three  different  forces.  First,  the  abdominal 
organs,  which  have  been  pushed  out  of  their 
usual  position  by  the  descent  of  the  diaphragm,  fall  backward  by 
their  own  weight  and  carry  upward  the  relaxed  diaphragm  before 
them.  Secondly,  the  costal  cartilages,  which  are  slightly  twisted 
out  of  shape  when  the  ribs  are  drawn  upward,  resume  their  natural 
position  as  soon  as  the  muscles  are  relaxed,  and,  drawing  the  ribs 
down  again,  compress  the  sides  of  the  chest.  Thirdly,  the  pul- 
monary tissue,  as  we  have  already  remarked,  is  abundantly  sup- 
plied with  yellow  elastic  fibres,  which  retract  by  virtue  of  their 
own  elasticity,  in  every  part  of  the  lungs,  after  they  have  been 
forcibly  distended,  and,  compressing  the  pulmonary  vesicles,  drive 
out  a  portion  of  the  air  which  they  contained.     By  the  constant 


Diagram    illustratingi 

THE  ReSPIRATORT  MOVE- 
MENTS.— a.  Cavity  of  the  chest. 
h.  Diaphragm.  The  dark  out- 
lines show  the  figure  of  the  chest 
when  collapsed  ;  the  dotted  lines 
show  the  same  when  expanded. 


RESPIEATOEY    MOVEMENTS    OF    THE    CHEST.  203 

recurrence  of  these  alternating  movements  of  inspiration  and  expi- 
ration, fresh  portions  of  air  are  constantly  introduced  into  and 
expelled  from  the  chest. 

The  whole  of  the  air,  however,  is  not  exchanged  at  each  move- 
ment of  respiration.  On  the  contrary,  a  very  considerable  quantity 
remains  in  the  pulmonary  cavity  after  the  most  complete  expira- 
tion; and  even  after  the  lungs  have  been  removed  from  the  chest, 
they  still  contain  a  large  quantity  of  air  which  cannot  be  entirely 
displaced  by  any  violence  short  of  disintegrating  and  disorganizing 
the  pulmonary  tissue.  It  is  evident,  therefore,  that  only  a  com- 
paratively small  portion  of  the  air  in  the  lungs  passes  in  and  out 
with  each  respiratory  movement ;  and  it  will  require  several  suc- 
cessive respirations  before  all  the  air  in  the  chest  can  be  entirely 
changed.  It  has  not  been  possible  to  ascertain  with  certainty  the 
exact  proportion  in  volume  which  exists  between  the  air  which  is 
alternately  inspired  and  expired,  or  "tidal"  air,  and  that  which 
remains  constantly  in  the  chest,  or  "residual"  air,  as  it  is  called. 
It  has  been  estimated,  however,  by  Dr.  Carpenter,^  from  the  reports 
of  various  observers,  that  the  volume  of  inspired  and  expired  air 
varies  from  10  to  13  per  cent,  of  the  entire  quantity  contained  in 
the  chest.  If  this  estimate  be  correct,  it  will  require  from  eight  to 
ten  respirations  to  change  the  whole  quantity  of  air  in  the  cavity 
of  the  chest. 

It  is  evident,  however,  from  the  foregoing,  that  the  inspiratory 
and  expiratory  movements  of  the  chest  cannot  be  sufficient  to 
change  the  air  at  all  in  the  pulmonary  l©bules  and  vesicles.  The 
air  which  is  drawn*  in  with  each  inspiration  penetrates  only  into 
the  trachea  and  bronchial  tubes,  until  it  occupies  the  place  of  that 
which  was  driven  out  by  the  last  expiration.  By  the  ordinary 
respiratory  movements,  therefore,  only  that  small  portion  of  the 
air  lying  nearest  the  exterior,  in  the  trachea  and  large  bronchi 
would  fluctuate  backward  and  forward,  without  ever  penetrating 
into  the  deeper  parts  of  the  lung,  were  there  no  other  means  pro- 
vided for  its  renovation.  There  are,  however,  two  other  forces  in 
play  for  this  purpose.  The  first  of  these  is  the  diffusive  power  of 
the  gases  themselves.  The  air  remaining  in  the  deeper  parts  of 
the  chest  is  richer  in  carbonic  acid  and  poorer  in  oxygen  than  that 
which  has  been  recently  inspired ;  and  by  the  laws  of  gaseous  dif- 
fusion there  must  be  a  constant  interchange  of  these  gases  between 

'  Human  Physiology,  Philada.  ed.,  1855,  p.  300. 


204  EESPIEATION. 

the  pulmonary  vesicles  and  the  trachea,  tending  to  mix  them 
equally  in  all  parts  of  the  lung.  This  mutual  diffusion  and  inter- 
mixture of  the  gases  will  therefore  tend  to  renovate,  partially  at 
least,  the  air  in  the  pulmonary  lobules  and  vesicles.  Secondly  the 
trachea  and  bronchial  tubes,  down  to  those  even  of  the  smallest 
size,  are  lined  with  a  mucous  membrane  which  is  covered  with  a 
ciliated  epithelium.  The  movement  of  these  cilia  is  found  to  be 
directed  always  from  below  upward ;  and,  like  ciliary  motion 
wherever  it  occurs,  has  the  effect  of  producing  a  current  in  the 
same  direction,  in  the  fluids  covering  the  mucous  membrane.    The 

air  in  the  tubes  must  partici- 
Fig-  72.  pate,  to   a   certain   extent,  in 

■|H|BBHB^BH|HBBBB^H     this  and    a    double 

^^^S^^^^^^^^^H^^^^^^H  stream  of  air  therefore  is  estab- 
^KKmljjj^  lished  in  each  bronchial  tube; 

^/^^^BS^S/K^^^^^^^^^  current  passing  from  with- 

^^^^P^^PI^^^^^^^^^^^B  in  outward  along  the  walls  of 
^^^^^M^HHMj^^^^^^^HU     the  tube,  and  a  return 

^    .       ,      ,     passing  from  without  inward, 

Small  Bronchial  Tube,    showing  outward       r  o  i 

and  inward  current,  produced  by  ciliary  motion.  alono"    the    Central    part    of    itS 

cavity.  (Fig.  72.)  By  this 
means  a  kind  of  aerial  circulation  is  constantly  maintained  in  the 
interior  of  the  bronchial  tubes ;  which,  combined  with  the  mutual 
diffusion  of  the  gases  and  the  alternate  expansion  and  collapse  of 
the  chest,  effectually  accomplish  the  renovation  of  the  air  contained 
in  all  parts  of  the  pulmonary  cavity. 

Eespiratory  Movements  of  the  Glottis. — Beside  the  move- 
ments of  expansion  and  collapse  already  described,  belonging  to 
the  chest,  there  are  similar  respiratory  movements  which  take  place 
in  the  larynx.  If  the  respiratory  passages  be  examined  after  death, 
in  the  state  of  collapse  in  which  they  are  usually  found,  it  will  be 
noticed  that  the  opening  of  the  glottis  is  very  much  smaller  than 
the  cavity  of  the  trachea  below.  The  glottis  itself  presents  the 
appearance  of  a  narrow  chink,  while  the  passage  for  the  inspired 
air  widens  in  the  lower  part  of  the  larynx,  and  in  the  trachea 
constitutes  a  spacious  tube,  nearly  cylindrical  in  shape,  and  over 
half  an  inch  in  diameter.  We  have  found,  for  instance,  that  in 
the  human  subject  the  space  included  between  the  vocal  chords 
has  an  area  of  only  0.15  to  0.17  square  inch ;  while  the  calibre 
of  the  trachea  in  the  middle  of  its  length  is  0.45  square  inch. 


RESPIRATORY    MOVEMENTS    OF    THE    GLOTTIS. 


205 


This  disproportion,  however,  which  is  so  evident  after  death,  does 
not  exist  during  life.  While  respiration  is  going  on,  there  is  a 
constant  and  regular  movement  of  the  vocal  chords,  synchronous 
with  the  inspiratory  and  expiratory  movements  of  the  chest,  by 


Fig.  73. 


Fig.  74. 


Human  Larynx,  viewed  from  above 
in  its  ordinary  post-mortem  condition. — a. 
Vocal  chords,  b.  Thyroid  cartilage,  cc.  Ary- 
tenoid cartilages,    o.  Opening  of  the  glottis. 


The  same,  with  the  glottis  opened  by 
separation  of  the  vocal  chords. — a.  Vocal 
chords.  6.  Thyroid  cartilage,  vc.  Aryte- 
noid cartilages,    o.  Opening  of  the  glottis. 


Fig.  75. 


which  the  size  of  the  glottis  is  alternately  enlarged  and  diminished. 
At  every  inspiration,  the  glottis  opens  and  allows  the  air  to  pass 
freely  into  the  trachea ;  at  every  expiration  it  collapses,  and  the 
air  is  driven  out  through  it  from  be- 
low. These  movements  are  called  the 
"  respiratory  movements  of  the  glottis." 
They  correspond  in  ev«ry  respect  with 
those  of  the  chest,  and  are  excited  or 
retarded  by  similar  causes.  When- 
ever the  general  movements  of  respira- 
tion are  hurried  and  labored,  those  of 
the  glottis  become  accelerated  and  in- 
creased in  intensity  at  the  same  time ; 
and  when  the  movements  of  the  chest 
are  slower  or  fainter  than  usual,  owing 
to  debility,  coma,  or  the  like,  those  of 
the  glottis  are  diminished  in  the  same 
proportion. 

1.1         „     „•      ,                     ,•                ^ii  Human     Larynx,    POSTERIOR 
n   the  respiratory  motions  of  the  viEw.-a.  Thyroid  cartilage.  6.  Epi- 
glottis,   as    in    those    of    the    chest,    the  glottis,    cc.   Arytenoid  cartilages,    d. 
,        ry     •          ...           .                        .  Cricoid  cartilage,    ee.   Posterior  crico- 
movement    Ot     inspiration    is    an    active  arytenoid  muscles.  /.  Trachea. 


206  EESPIRATION. 

one,  and  that  of  expiration  passive.  In  inspiration,  the  glottis  is 
opened  by  contraction  of  the  posterior  crico-arytenoid  muscles. 
(Fig.  75.)  These  muscles  originate  from  the  posterior  surface  of 
the  cricoid  cartilage,  near  the  median  line;  and  their  fibres,  running 
upward  and  outward,  are  inserted  into  the  external  angle  of  the 
arytenoid  cartilages.  By  the  contraction  of  these  muscles,  during 
the  movement  of  inspiration,  the  arytenoid  cartilages  are  rotated 
upon  their  articulations  with  the  cricoid,  so  that  their  anterior 
extremities  are  carried  outward,  and  the  vocal  chords  stretched  and 
separated  from  each  other.  (Fig.  74.)  In  this  way,  the  size  of  the 
glottis  may  be  increased  from  0.16  to  0.27  square  inch. 

In  expiration,  the  posterior  crico-arytenoid  muscles  are  relaxed, 
and  the  elasticity  of  the  vocal  chords  brings  them  back  to  their 
former  position. 

The  motions  of  respiration  consist,  therefore,  of  two  sets  of  move- 
ments :  viz.,  those  of  the  chest,  and  those  of  the  glottis.  These  move- 
ments, in  the  natural  condition,  correspond  with  each  other  both  in 
time  and  intensity.  It  is  at  the  same  time  and  by  the  same  nervous 
influence,  that  the  chest  expands  to  inhale  the  air,  while  the  glottis 
opens  to  admit  it ;  and  in  expiration,  the  miiscles  of  both  chest  and 
glottis  are  relaxed,  while  the  elasticity  of  the  tissues,  by  a  kind  of 
passive  contraction,  restores  the  parts  to  their  original  condition. 


CHANGES  IN  THE  AIR  DURING  RESPIRATION. 

The  atmospheric  air,  as  it  is  drawn  into  the  cavity  of  the  lungs, 
is  a  mixture  of  oxygen  and  nitrogen,  in  the  proportion  of  about  21 
per  cent.,  by  volume,  of  oxygen,  to  79  per  cent,  of  nitrogen.  It 
also  contains  about  one-twentieth  per  cent,  of  carbonic  acid,  a  vary- 
ing quantity  of  watery  vapor,  and  some  traces  of  ammonia.  If  col- 
lected and  examined,  after  passing  through  the  lungs,  it  is  found  to 
have  become  altered  in  the  following  essential  particulars,  viz : — 

1st.  It  has  lost  oxygen. 

2d.  It  has  gained  carbonic  acid.     And 

3d.  It  has  absorbed  the  vapor  of  water. 

Beside  the  two  latter  substances,  there  are  also  exhaled  with  the 
expired  air  a  very  small  quantity  of  nitrogen,  over  and  above  what 
was  taken  in  with  inspiration,  and  a  little  animal  matter  in  a 
gaseous  form,  which  communicates  a  slight  but  peculiar  odor  to 
the  breath.     The  air  is  also  somewhat  elevated  in  temperature,  by 


CHANGES    IN    THE    BLOOD    DURING    RESPIRATION.      207 

contact  with  the  pulmonary  mucous  membrane.  By  far  the  most 
important  part,  however,  of  the  above  changes  suffered  by  the  air, 
consists  in  its  loss  of  ox3^gen,  and  its  absorption  of  carbonic  acid. 

The  oxygen  which  disappears  from  the  inspired  air  is  not  entirely 
replaced  in  the  carbonic  acid  exhaled  ;  that  is,  there  is  less  oxygen 
in  the  carbonic  acid  which  is  returned  to  the  air  by  expiration  than 
has  been  lost  during  inspiration. 

There  is  even  more  oxygen  absorbed  than  is  given  off  again  in 
both  the  carbonic  acid  and  aqueous  vapor  together,  which  are 
exhaled  from  the  lungs.^  There  is,  then,  a  constant  disappearance 
of  oxygen  from  the  air  used  in  respiration,  and  a  constant  accumu- 
lation of  carbonic  acid. 

The  proportion  of  oxygen  which  disappears  in  the  interior  of  the 
body,  over  and  above  that  which  is  returned  in  the  breath  under 
the  form  of  carbonic  acid,  varies  in  different  kinds  of  animals.  In 
the  herbivora,  it  is  about  10  per  cent,  of  the  whole  amount  of  oxy- 
gen inspired ;  in  the  carnivora,  20  or  25  per  cent,,  and  even  more. 
It  is  a  very  remarkable  fact,  also,  and  an  important  one,  as  regards 
the  theory  of  respiration,  that,  in  the  same  animal,  the  proportion  of 
oxygen  absorbed,  to  that  of  carbonic  acid  exhaled,  varies  according 
to  the  quality  of  the  food.  In  dogs,  for  instance,  while  fed  on  ani- 
mal food,  according  to  the  experiments  of  Eegnault  and  Eeiset,  25 
per  cent,  of  the  inspired  oxygen  disappeared  in  the  body  of  the 
animal;  but  when  fed  on  starchy  substances,  all  but  8  per  cent, 
reappeared  in  the  expired  carbonic  acid.  It  is  already  evident,  there- 
fore, from  these  facts,  that  the  oxygen  of  the  inspired  air  is  not 
altogether  employed  in  the  formation  of  carbonic  acid. 


CHANGES  IN  THE  BLOOD  DURING  RESPIRATION. 

If  we  pass  from  the  consideration  of  the  changes  produced  in  the 
air  by  respiration  to  those  which  take  place  in  the  blood  during  the 
same  process,  we  find,  as  might  have  been  expected,  that  the  latter 
correspond  inversely  with  the  former.  The  blood,  in  passing 
through  the  lungs,  suffers  the  following  alterations : — 

1st.  Its  color  is  changed  from  venous  to  arterial. 

2d.  It  absorbs  oxygen.     And 

8d.  It  exhales  carbonic  acid  and  the  vapor  of  water. 

'  Lehmann's  Physiological  Chemistry,  Philada.  ed.,  vol.  ii.  p.  432. 


208  EESPIRATION. 

The  interchange  of  gases,  which  takes  place  during  respiration 
between  the  air  and  the  blood,  is  a  simple  phenomenon  of  absorp- 
tion and  exhalation.  The  inspired  oxygen  does  not,  as  Lavoisier 
once  supposed,  immediately  combine  with  carbon  in  the  lungs,  and 
return  to  the  atmosphere  under  the  form  of  carbonic  acid.  On  the 
contrary,  almost  the  first  fact  of  importance  which  has  been  estab- 
lished by  the  examination  of  the  blood  in  this  respect  is  the  fol- 
lowing, viz :  that  carbonic  acid  exists  ready  formed  in  the  venous  blood 
before  its  entrance  into  the  lungs ;  and,  on  the  other  hand,  that  the 
oxygen  which  is  absorbed  during  respiration  passes  off  in  a  free  state 
with  the  arterial  blood.  The  real  process,  as  it  takes  place  in  the 
lung,  is,  therefore,  for  the  most  part,  as  follows :  The  blood  comes 
to  the  lungs  already  charged  with  carbonic  acid.  In  passing  through 
the  pulmonary  capillaries,  it  is  exposed  to  the  influence  of  the  air 
in  the  cavity  of  the  pulmonary  cells,  and  a  transudation  of  gases 
takes  place  through  the  moist  animal  membranes  of  the  lung. 
Since  the  blood  in  the  capillaries  contains  a  larger  proportion 
of  carbonic  acid  than  the  air  in  the  air-vesicles,  a  portion  of  this 
gas  leaves  the  blood  and  passes  out  through  the  pulmonary  mem- 
brane ;  while  the  oxygen,  being  more  abundant  in  the  air  of  the 
vesicles  than  in  the  circulating  fluid,  passes  inward  at  the  same 
time,  and  is  condensed  by  the  blood. 

In  this  double  phenomenon  of  exhalation  and  absorption,  which 
takes  place  in  the  lungs,  both  parts  of  the  process  are  equally 
necessary  to  life.  It  is  essential  for  the  constant  activity  and  nutri- 
tion of  the  tissues  that  they  be  steadily  supplied  with  oxygen  by 
the  blood ;  and  if  this  supply  be  cut  off,  their  functional  activity 
ceases.  On  the  other  hand,  the  carbonic  acid  which  is  produced  in. 
the  body  by  the  processes  of  nutrition  becomes  a  poisonous  sub- 
stance, if  it  be  allowed  to  collect  in  large  quantity.  Under  ordinary 
circumstances,  the  carbonic  acid  is  removed  by  exhalation  through 
the  lungs  as  fast  as  it  is  produced  in  the  interior  of  the  body ;  but 
if  respiration  be  suspended,  or  seriously  impeded,  since  the  produc- 
tion of  carbonic  acid  continues,  while  its  elimination  is  prevented, 
it  accumulates  in  the  blood  and  in  the  tissues,  and  terminates  life 
in  a  few  moments,  by  a  rapid  deterioration  of  the  circulating  fluid, 
and  more  particularly  by  its  poisonous  effect  on  the  nervous  system. 

The  deleterious  effects  of  breathing  in  a  confined  space  will 
therefore  very  soon  become  apparent.  As  respiration  goes  on,  the 
oxygen  of  the  air  constantly  diminishes,  and  the  carbonic  acid, 
mingled  with  it  by  exhalation,  increases  in  quantity.     After  a  time 


CHANGES    OF    THE    BLOOD    DURING    RESPIRATION.      209 

the  air  becomes  accordingly  so  poor  in  oxygen  that,  by  that  fact 
alone,  it  is  incapable  of  supporting  life.  At  the  same  time,  the 
carbonic  acid  becomes  so  abundant  in  the  air  vesicles  that  it  prevents 
the  escape  of  that  which  already  exists  in  the  blood ;  and  the  dele- 
terious effect  of  its  accumulation  in  the  circulating  fluid  is  added 
to  that  produced  by  a  diminished  supply  of  oxygen.  An  increased 
proportion  of  carbonic  acid  in  the  atmosphere  is  therefore  injurious 
in  a  similar  manner,  although  there  may  be  no  diminution  of  oxy- 
gen; since  by  its  presence  it  impedes  the  elimination  of  the  carbonic 
acid  already  formed  in  the  blood,  and  induces  the  poisonous  effects 
which  result  from  its  accumulation. 

Examination  of  the  blood  shows  furthermore  that  the  interchange 
of  gases  in  the  lungs  is  not  complete  but  only  partial  in  its  extent. 
It  results  from  the  experiments  of  Magendie,  Magnus,  and  others, 
that  both  oxygen  and  carbonic  acid  are  contained  in  both  venous 
and  arterial  blood.  Magnus'  found  that  the  proportion  of  oxygen 
to  carbonic  acid,  by  volume,  in  arterial  blood  was  as  10  to  25 ;  in 
venous  blood  as  10  to  40.  The  venous  blood,  then,  as  it  arrives  at 
the  lungs,  still  retains  a  remnant  of  the  oxygen  which  it  had  pre- 
viously absorbed ;  and  in  passing  through  the  pulmonary  capillaries 
it  gives  off  only  a  part  of  the  carbonic  acid  with  which  it  has 
become  charged  in  the  general  circulation. 

The.  oxygen  and  carbonic  acid  of  the  blood  exist  in  a  state  of 
solution  in  the  circulating  fluid,  and  not  in  a  state  of  intimate  chemi- 
cal combination.  This  is  shown  by  the  fact  that  both  of  these 
substances  may  be  withdrawn  from  the  blood  by  simple  exhaustion 
with  an  air  pump,  or  by  a  stream  of  any  other  indifferent  gas,  such 
as  hydrogen,  which  possesses  sufficient  physical  displacing  power. 
Magnus  found^  that  freshly  drawn  arterial  blood  yielded  by  simple 
agitation  with  carbonic  acid  more  than  10  per  cent,  of  its  volume 
of  oxygen.  The  carbonic  acid  may  also  be  expelled  from  venous 
blood  by  a  current  of  pure  oxygen,  or  of  hydrogen,  or,  in  great 
measure,  by  simple  agitation  with  atmospheric  air.  There  is  some 
difficulty  in  determining,  however,  whether  the  carbonic  acid  of  the 
blood  be  altogether  in  a  free  state,  or  whether  it  be  partly  in  a 
state  of  loose  chemical  combination  with  a  base,  under  the  form  of 
an  alkaline  bicarbonate.  A  solution  of  bicarbonate  of  soda  itself 
will  lose  a  portion  of  its  carbonic  acid,  and  become  reduced  to  the 

'  In  Lehmann,  op.  cit.,  vol.  i.  p.  570.  • 

^  In  Robin  and  Verdeil,  op.  cit.,  vol.  ii.  p.  34. 
14 


210  EESPIRATION". 

condition  of  a  carbonate,  bj  simple  exhaustion  under  the  air-pump, 
or  by  agitation  with  pure  hydrogen  at  the  temperature  of  the  body. 
Lehmann  has  found'  that  after  the  expulsion  of  all  the  carbonic 
acid  removable  by  the  air-pump  and  a  current  of  hydrogen,  there 
still  remains,  in  ox's  blood,  0.1628  per  cent,  of  carbonate  of  soda; 
and  he  estimates  that  this  quantity  is  sufficient  to  have  retained  all 
tbe  carbonic  acid,  previously  given  off",  in  the  form  of  a  bicarbonate. 
It  makes  little  or  no  difference,  however,  so  far  ar  regards  the  pro- 
cess of  respiration,  whether  the  carbonic  acid  of  the  blood  exist  in 
an  entirely  free  state,  or  under  the  form  of  an  alkaline  bicarbonate ; 
since  it  may  be  readily  removed  from  this  combination,  at  the  tem- 
perature of  the  body,  by  contact  with  an  indifferent  gas. 

The  oxygen  and  carbonic  acid  of  the  blood  are  in  solution  prin- 
cipally in  the  blood- globules,  and  not  in  the  plasma.  The  researches 
of  Magnus  have  shown^  that  the  blood  holds  in  solution  2|  times 
as  much  oxygen  as  pure  water  could  dissolve  at  the  same  tempera- 
ture; and  that  while  the  serum  of  the  blood,  separated  from  the 
globules,  exerts  no  more  solvent  power  on  oxygen  than  pure  water, 
defibrinated  blood,  that  is,  the  serum  and  globules  mixed,  dissolves 
quite  as  much  oxygen  as  the  fresh  blood  itself.  The  same  thing  is 
true  with  regard  to  the  carbonic  acid.  It  is  therefore  the  semi- 
fluid blood-globules  which  retain  these  two  gases  in  solution ;  and 
since  the  color  of  the  blood  depends  entirely  upon  that  of  the  glo- 
bules, it  is  easy  to  understand  why  the  blood  should  alter  its  hue 
from  purple  to  scarlet  in  passing  through  the  lungs,  where  the 
globules  give  up  carbonic  acid,  and  absorb  a  fresh  quantity  of 
oxygen.  The  above  change  may  readily  be  produced  outside  the 
body.  If  freshly  drawn  venous  blood  be  shaken  in  a  bottle  with, 
pure  oxygen,  its  color  changes  at  once  from  purple  to  red ;  and  the 
same  change  will  take  place,  though  more  slowly,  if  the  blood  be 
simply  agitated  with  atmospheric  air.  It  is  for  this  reason  that  the 
surface  of  defibrinated  venous  blood,  and  the  external  parts  of  a 
dark-colored  clot,  exposed  to  the  atmosphere,  become  rapidly  red- 
dened, while  the  internal  portions  retain  their  original  color. 

The  process  of  respiration,  so  far  as  we  have  considered  it,  con- 
sists in  an  alternate  interchange  of  carbonic  acid  and  oxygen  in  the 
blood  of  the  general  and  pulmonary  circulations.  In  the  pulmonary 
circulation,  carbonic  acid  is  given  off  and  oxygen  absorbed ;  while 

'  Op.  cit.,  vol.  i.  p.  393. 

2  In  Robin  and  Verdeil,  op.  cit.,  vol.  ii.  pp.  28—32. 


CHANGES    OF    THE    BLOOD    DURING    RESPIRATION.      211 

in  the  general  circulation  tlie  oxygen  gradually  disappears,  and  is 
replaced,  in  the  venous  blood,  by  carbonic  acid.  The  oxygen' which 
thus  disappears  from  the  blood  in  the  general  circulation  does  not, 
for  the  most  part,  enter  into  direct  combination  in  the  blood  itself. 
On  the  contrary,  it  exists  there,  as  we  have  already  stated,  in  the 
form  of  a  simple  solution.  It  is  absorbed,  however,  from  the  blood 
of  the  capillary  vessels,  and  becomes  fixed  in  the  substance  of  the 
vascular  tissues.  The  blood  may  be  regarded,  therefore,  in  this 
respect,  as  a  circulating  fluid,  destined  to  transport  oxygen  from  the 
lungs  to  the  tissues ;  for  it  is  the  tissues  themselves  which  finally 
appropriate  the  oxygen,  and  fix  it  in  their  substance. 

The  next  important  question  which  presents  itself  in  the  study 
of  the  respiratory  process  relates  to  the  origin  of  the  carbonic  acid  in 
the  venous  blood.  It  was  formerly  supposed,  when  Lavoisier  first 
discovered  the  changes  produced  in  the  air  by  respiration,  that  the 
production  of  the  carbonic  acid  could  be  accounted  for  in  a  very 
simple  manner.  It  was  thought  to  be  produced  in  the  lungs  by  a 
direct  union  of  the  inspired  oxygen  with  the  carbon  of  the  blood 
in  the  pulmonary  vessels.  It  was  found  afterward,  however,  that 
this  could  not  be  the  case;  since  carbonic  acid  exists  already  formed 
in  the  blood,  previous  to  its  entrance  into  the  lungs.  It  was  then 
imagined  that  the  oxidation  of  carbon,  and  the  consequent  produc- 
tion of  carbonic  acid,  took  place  in  the  capillaries  of  the  general 
circulation,  since  it  could  not  be  shown  to  take  place  in  the  lungs, 
nor  between  the  lungs  and  the  capillaries.  The  truth  is,  however, 
that  no  direct  evidence  exists  of  such  a  direct  oxidation  taking 
place  anywhere.  The  formation  of  carbonic  acid,  as  it  is  now 
understood,  takes  place  in  three  different  modes:  1st,  in  the  lungs; 
2d,  in  the  blood;  and  3d,  in  the  tissues. 

First,  in  the  lungs.  There  exists  in  the  pulmonary  tissue  a  pecu- 
liar acid  substance  first  described  by  Yerdeil'  under  the  name  of 
" pneumic"  or  "pulmonic"  acid.  It  is  a  crystallizable  body,  soluble 
in  water,  which  is  produced  in  the  substance  of  the  pulmonary 
tissue  by  transformation  of  some  of  its  other  ingredients,  in  the 
same  manner  as  sugar  is  produced  in  the  tissue  of  the  liver.  It  is 
on  account  of  the  presence  of  this  substance  that  the  fresh  tissue  of 
the  lung  has  usually  an  acid  reaction  to  test-paper,  and  that  it  has 
also  the  property,  which  has  been  noticed  by  several  observers,  of 

'  Robin  and  Verdeil,  op.  cit.,  vol.  ii.  p.  460. 


212  EESPIRATION. 

decomposing  the  metallic  cyanides,  with  the  production  of  hydro- 
cyanic acid  ;  a  property  not  possessed  by  sections  of  areolar  tissue, 
the  internal  surface  of  the  skin,  &c.  &c.  When  the  blood,  there- 
fore, comes  in  contact  with  the  pulmonary  tissue,  which  is 
permeated  everywhere  by  pneumic  acid  in  a  soluble  form,  its 
alkaline  carbonates  and  bicarbonates,  if  any  be  present,  are  decom- 
posed with  the  production  on  the  one  hand  of  the  pneumates  of 
soda  and  potass,  and  on  the  other  of  free  carbonic  acid,  which  is 
exhaled,  M,  Bernard  has  found^  that  if  a  solution  of  bicarbonate 
of  soda  be  rapidly  injected  into  the  jugular  vein  of  a  rabbit,  it 
becomes  decomposed  in  the  lungs  with  so  rapid  a  development  of 
carbonic  acid,  that  the  gas  accumulates  in  the  pulmonary  tissue, 
and  even  in  the  pulmonary  vessels  and  the  cavities  of  the  heart,  to 
such  an  extent  as  to  cause  immediate  death  by  stoppage  of  the 
circulation.  In  the  normal  condition,  however,  the  carbonates  and 
bicarbonates  of  the  blood  arrive  so  slowly  at  the  lungs  that  as  fast 
as  they  are  decomposed  there,  the  carbonic  acid  is  readily  exhaled 
by  expiration,  and  produces  no  deleterious  efiect  on  the  circulation. 

Secondly,  in  the  blood.  There  is  little  doubt,  although  the  fact  has 
not  been  directly  proved,  that  some  of  the  oxygen  definitely  dis- 
appears, and  some  of  the  carbonic  acid  is  also  formed,  in  the  sub- 
stance of  the  blood-globules  during  their  circulation.  Since  these 
globules  are  anatomical  elements,  and  since  they  undoubtedly  go 
through  with  nutritive  processes  analogous  to  those  which  take 
place  in  the  elements  of  the  solid  tissues,  there  is  no  reason  for  dis- 
believing that  they  also  require  oxygen  for  their  support,  and  that 
they  produce  carbonic  acid  as  one  of  the  results  of  their  interstitial 
decomposition.  While  the  oxygen  and  carbonic  acid,  therefore, 
contained  in  the  globule^,  are  for  the  most  part  transported  by 
these  bodies  from  the  lungs  to  the  tissues,  and  from  the  tissues  back 
again  to  the  lungs,  they  probably  take  part,  also,  to  a  certain  extent, 
in  the  nutrition  of  the  blood-globules  themselves. 

Thirdly,  in  the  tissues.  This  is  by  far  the  most  important  source 
of  the  carbonic  acid  in  the  blood.  From  the  experiments  of  Spal- 
lanzani,  W,  Edwards,  Marchand  and  others,  the  following  very 
important  fact  has  been  established,  viz.,  that  every  organized  tissue 
and  even  every  organic  substance,  when  in  a  recent  condition,  has  the 
power  of  absorbing  oxygen  and  of  exhaling  carbonic  acid.  G,  Liebig, 
for  example,^  found  that  frog's  muscles,  recently  prepared  and  com- 

'  Archives  Gen.  de  Med,,  xvi,  222.         ^  In  Lehmann,  op.  cit.,  vol.  ii.  p.  474. 


CHANGES    OF    THE    BLOOD    DURING    RESPIRATION.      213 

pletely  freed  from  blood,  continued  to  absorb  oxygen  and  discharge 
carbonic  acid.  Similar  experiments  with  other  tissues  have  led 
to  a  similar  result.  The  interchange  of  gases,  therefore,  in  the 
process  of  respiration,  takes  place  mostly  in  the  tissues  themselves. 
It  is  in  their  substance  that  the  oxygen  becomes  fixed  and  assimi- 
lated, and  that  the  carbonic  acid  takes  its  origin.  As  the  blood  in 
the  lungs  gives  up  its  carbonic  acid  to  the  air,  and  absorbs  oxygen 
from  it,  so  in  the  general  circulation  it  gives  up  its  oxygen  to  the 
tissues,  and  absorbs  from  them  carbonic  acid. 

We  come  lastly  to  examine  the  exact  mode  by  which  the  car- 
bonic acid  originates  in  the  animal  tissues.  Investigation  shows  that 
even  here  it  is  not  produced  hy  a  process  of  oxidation,  or  direct  union 
of  oxygen  ivith  the  carbon  of  the  tissues,  hut  in  some  other  and  more 
indirect  mode.  This  is  proved  by  the  fact  that  animals  and  fresh 
animal  tissues  will  continue  to  exhale  carbonic  acid  in  an  atmo- 
sphere of  hydrogen  or  of  nitrogen,  or  even  when  placed  in  a  vacuum. 
Marchand  found*  that  frogs  would  live  for  from  half  an  hour  to  an 
hour  in  pure  hydrogen  gas  ;  and  that  during  this  time  they  exhaled 
even  more  carbonic  acid  than  in  atmospheric  air,  owing  probably 
to  the  superior  displacing  power  of  hydrogen  for  carbonic  acid. 
For  while  15,500  grains'  weight  of  frogs  exhaled  about  1.13  grain 
of  carbonic  acid  per  hour  in  atmospheric  air,  they  exhaled  during 
the  same  time  in  pure  hydrogen  as  much  as  4.07  grains.  The  same 
observer  found  that  frogs  would  recover  on  the  admission  of  air 
after  remaining  for  nearly  half  an  hour  in  a  nearly  complete 
vacuum ;  and  that  if  they  were  killed  by  total  abstraction  of  the 
air,  15,500  grains  weight  of  the  animals  were  found  to  have 
eliminated  9.3  grains  of  carbonic  acid.  The  exhalation  of  carbonic 
acid  by  the  tissues  does  not,  therefore,  depend  directly  upon  the 
access  of  free  oxygen.  It  cannot  go  on,  it  is  true,  for  an  indefinite 
time,  any  more  than  the  other  vital  processes,  without  the  presence 
of  oxygen.  But  it  may  continue  long  enough  to  show  that  the 
carbonic  acid  exhaled  is  not  a  direct  product  of  oxidation,  but  that 
it  originates,  on  the  contrary,  in  all  probability,  by  a  decomposi- 
tion of  the  organic  ingredients  of  the  tissues,  resulting  in  the  "pro- 
duction of  carbonic  acid  on  the  one  hand,  and  of  various  other 
substances  on  the  other,  with  which  we  are  not  yet  fully  acquainted; 
in  very  much  the  same  manner  as  the  decomposition  of  sugar 
during  fermentation  gives  rise  to  alcohol  on  the  one  hand  and  to 

'  Lehmann,  op.  cit.,  vol.  ii.  p.  442. 


214 


KESPIRATION. 


carbonic  acid  on  the  other.  The  fermentation  of  sugar,  when  it  has 
once  commenced,  does  not  require  the  continued  access  of  air.  It 
will  go  on  in  an  atmosphere  of  hydrogen,  or  even  when  confined  in 
a  close  vessel  over  mercury;  since  its  carbonic  acid  is  not  produced 
by  direct  oxidation,  but  by  a  decomposition  of  the  sugar  already 
present.  For  the  same  reason,  carbonic  acid  will  continue  to  be 
exhaled  by  living  or  recently  dead  animal  tissues,  even  in  an  atmo- 
sphere of  hydrogen,  or  in  a  vacuum. 

Carbonic  acid  makes  its  appearance,  accordingly,  in  the  tissues, 
as  one  product  of  their  decomposition  in  the  nutritive  process. 
From  them  it  is  taken  up  by  the  blood,  either  in  simple  solution  or 
in  loose  combination  as  a  bicarbonate,  transported  by  the  circulation 
to  the  lungs,  and  finally  exhaled  from  the  pulmonary  mucous  mem- 
brane in  a  gaseous  form. 

•  The  carbonic  acid  exhaled  from  the  lungs  should  accordingly  be 
studied  by  itself  as  one  of  the  products  of  the  animal  organism,  and 
its  quantity  ascertained  in  the  different  physiological  conditions  of 
the  body.  According  to  the  researches  of  Vierordt,^  which  are 
regarded  as  the  most  accurate  on  this  subject,  an  adult  man  gives 
off  1.62  cubic  inch  of  carbonic  acid  with  each  normal  expiration. 
This  would  give  19.16  cubic  inches  per  minute,  1149.6  cubic  inches 
per  hour,  and  15.4  cubic  feet  per  day.  The  amount  of  carbonic 
acid  exhaled,  however,  varies  from  time  to  time,  according  to  many 
different  circumstances;  so  that  no  such  estimate  can  represent 
correctly  its  quantity  at  all  times.  These  variations  have  been 
very  fully  investigated  by  Andral  and  Gavarret,^  who  found  that 
the  principal  conditions  modifying  the  amount  of  this  gas  produced 
were  age,  sex,  constitution  and  development.  The  variations  were 
very  marked  in  different  individuals,  notwithstanding  that  the 
experiments  were  made  at  the  same  period  of  the  day,  and  with  the 
subject  as  nearly  as  possible  in  the  same  condition.  Thus  they 
found  that  the  quantity  of  carbonic  acid  exhaled  per  hour  in  five 
different  individuals  was  as  follows :— 


Quantity  of  Carbonic  Acid  pek  houb 

. 

In  subjec 

t  No.  1 1207 

cubic 

inches 

((         (I 

"2 970 

11 

" 

11         li 

"3         .         .         .         .         .     1250 

11 

11 

a            u 

"4         .         .       ".         .         .     1250 

11 

11 

(1            (f 

"5 1591 

11 

« 

'  In  Lehmann,  op.  cit.,  vol.  ii.  p.  439. 

^  Annales  de  Cliimie  et  de  Pharmacie,  1843,  vol.  viii.  p.  129. 


CHANGES    OF    THE    BLOOD    DUKING    RESPIRATION.      215 

With  regard  to  the  difference  produced  by  age,  it  was  found  that 
from  the  period  of  eight  years  up  to  puberty  the  quantity  of  car- 
bonic acid  increases  constantly  with  the  age.  Thus  a  boy  of  eight 
years  exhales,  on  the  average,  564  cubic  inches  per  hour ;  while  a 
boy  of  fifteen  years  exhales  981  cubic  inches  in  the  same  time. 
Boys  exhale  during  this  period  more  carbonic  acid  than  girls  of  the 
same  age.  In  males  this  augmentation  of  the  quantity  of  carbonic 
acid  continues  till  the  twenty-fifth  or  thirtieth  year,  when  it  reaches, 
on  the  average,  1398  cubic  inches  per  hour.  Its  quantity  then 
remains  stationary  for  ten  or  fifteen  years ;  then  diminishes  slightly 
from  the  fortieth  to  the  sixtieth  year;  and  after  sixty  years  dimi- 
nishes in  a  marked  degree,  so  that  it  may  fall  so  low  as  1038  cubic 
inches.  In  one  superannuated  person,  102  years  of  age,  Andral 
and  Gavarret  found  the  hourly  quantity  of  carbonic  acid  to  be 
only  665  cubic  inches. 

In  women,  the  increase  of  carbonic  acid  ceases  at  the  period  of 
puberty;  and  its  production  then  remains  constant  until  the  cessa- 
tion of  menstruation,  about  the  fortieth  or  forty -fifth  year.  At  that 
time  it  increases  again  until  after  fifty  years,  when  it  subsequently 
diminishes  v^ith  the  approach  of  old  age,  as  in  men.  Pregnancy, 
occurring  at  any  time  in  the  above  period,  imm.ediately  produces  a 
temporary  increase  in  the  quantity  of  carbonic  acid. 

The  strength  of  the  constitution,  and  more  particularly  the  deve- 
lopment of  the  muscular  system,  was  found  to  have  a  very  great 
influence  in  this  respect ;  increasing  the  quantity  of  carbonic  acid 
very  much,  in  proportion  to  the  weight  of  the  individual.  The 
largest  production  of  carbonic  acid  observed  was  in  a  young  man, 
26  years  of  age,  whose  frame  presented  a  remarkably  vigorous  and 
athletic  development,  and  who  exhaled  1591  cubic  inches  per  hour. 
This  large  quantity  of  carbonic  acid,  moreover,  in  well  developed 
persons,  is  not  owing  simply  to  the  size  of  the  entire  body,  but 
particularly  to  the  development  of  the  muscular  system,  since  an 
unusually  large  skeleton,  or  an  abundant  deposit  of  adipose  tissue, 
is  not  accompanied  by  any  such  increase  of  the  carbonic  acid. 

Andral  and  Gavarret  finally  sum  up  the  results  of  their  investiga- 
tions as  follows : — 

1.  The  quantity  of  carbonic  acid  exhaled  from  the  lungs  in  a 
given  time  varies  with  the  age,  the  sex,  and  the  constitution  of  the 
subject. 

2.  In  the  male,  as  well  as  in  the  female,  the  quantity  of  carbonic 


216  RESPIRATION. 

acid  varies  according  to  the  age;  and  that  independently  of  the 
weight  of  the  individual  subjected  to  experiment. 

3.  During  all  the  periods  of  life,  from  that  of  eight  years  up  to 
the  most  advanced  age,  the  male  and  female  may  be  distinguished 
by  the  different  quantities  of  carbonic  acid  which  they  exhale  in  a 
given  time.  Other  things  being  equal,  the  male  exhales  always  a 
larger  quantity  than  the  female.  This  difference  is  particularly 
marked  between  the  ages  of  16  and  40  years,  during  which  period 
the  male  usually  exhales  twice  as  much  carbonic  acid  as  the  female. 

4.  In  the  male,  the  quantity  of  carbonic  acid  increases  constantly 
from  eight  to  thirty  years ;  and  the  rate  of  this  increase  undergoes 
a  rapid  augmentation  at  the  period  of  puberty.  Beyond  thirty 
years  the  exhalation  of  carbonic  acid  begins  to  decrease,  and  its 
diminution  is  more  marked  as  the  individual  approaches  extreme 
old  age  ;  so  that  near  the  termination  of  life,  the  quantity  of  carbonic 
acid  produced  may  be  no  greater  than  at  the  age  of  ten  years. 

5.  In  the  female,  the  exhalation  of  carbonic  acid  increases  accord- 
ing to  the  same  law  as  in  the  male,  from  the  age  of  eight  years 
until  puberty.  But  at  the  period  of  puberty,  at  the  same  time 
with  the  appearance  of  menstruation,  the  exhalation  of  carbonic 
acid,  contrary  to  what  happens  in  the  male,  ceases  to  increase ;  and 
it  afterward  remains  stationary  so  long  as  the  menstrual  periods 
recur  with  regularity.  At  the  cessation  of  the  menses,  the  quantity 
of  carbonic  acid  exhaled  increases  in  a  notable  manner ;  then  it  de- 
creases again,  as  in  the  male,  as  the  woman  advances  toward  old  age. 

6.  During  the  whole  period  of  pregnancy,  the  exhalation  of  car- 
bonic acid  rises,  for  the  time,  to  the  same  standard  as  in  women 
whose  menses  have  ceased. 

7.  In  both  sexes,  and  at  all  ages,  the  quantity  of  carbonic  acid  is 
greater  as  the  constitution  is  stronger,  and  the  muscular  systeni 
more  fully  developed. 

Prof.  Scharling,  in  a  similar  series  of  investigations,'  found  that 
the  quantity  of  carbonic  acid  exhaled  was  greater  during  the  diges- 
tion of  food  than  in  the  fasting  condition.  It  is  greater,  also,  in  the 
waking  state  than  during  sleep ;  and  in  a  state  of  activity  than  in. 
one  of  quietude.  It  is  diminished,  also,  by  fatigue,  and  by  most 
conditions  which  interfere  with  perfect  health. 

The  process  of  respiration  is  not  altogether  confined  to  the  lungs, 

'  Annales  de  Chimie  et  de  Pharmacie,  vol.  viii.  p.  490. 


CHANGES    OF    THE    BLOOD    DURING    RESPIRATION.      217 

but  the  interchange  of  gases  takes  place,  also,  to  some  extent  through 
the  skin.  It  has  been  found,  by  inclosing  one  of  the  limbs  in  an 
air-tight  case,  that  the  air  in  which  it  is  confined  loses  oxygen  and 
gains  in  carbonic  acid.  By  an  experiment  of  this  sort,  performed  by 
Prof  Scharling,^  it  was  ascertained  that  the  carbonic  acid  given  off 
from  the  whole  cutaneous  surface,  in  the  human  subject,  is  from  one- 
sixtieth  to  one-thirtieth  of  that  discharged  during  the  same  period 
from  the  lungs.  In  the  true  amphibious  animals,  that  is,  those 
which  breathe  by  lungs,  and  can  yet  remain  under  water  for  an 
indefinite  period  without  injury  (as  frogs  and  salamanders),  the 
respiratory  function  of  the  skin  is  very  active.  In  these  animals, 
the  integument  is  very  vascular,  moist,  and  flexible;  and  is  covered, 
not  with  dry  cuticle,  but  with  a  very  thin  and  delicate  layer  of 
epithelium.  It,  therefore,  presents  all  the  conditions  necessary  for 
the  accomplishment  of  respiration;  and  while  the  animal  remains 
beneath  the  surface,  and  the  lungs  are  in  a  state  of  inactivity,  the 
exhalation  and  absorption  of  gases  continue  to  take  place  through 
the  skin,  and  the  process  of  respiration  goes  on  in  a  nearly  unin- 
terrupted manner. 

'  In  Carpenter's  Human  Physiology,  Philada.  ed.,  1855,  p   308. 


218  ANIMAL    HEAT. 


CHAPTER   XIII. 

ANIMAL  HEAT. 

One  of  the  most  important  phenomena  presented  by  animals  and 
vegetables  is  the  property  which  they  possess  of  maintaining,  more 
or  less  constantly,  a  standard  temperature,  notwithstanding  the 
external  vicissitudes  of  heat  and  cold  to  which  they  may  be  sub- 
jected. If  a  bar  of  iron,  or  a  jar  of  water,  be  heated  up  to  100° 
or  200°  F.,  and  then  exposed  to  the  air  at  50°  or  60°,  it  will  imme- 
diately begin  to  lose  heat  by  radiation  and  conduction ;  and  this 
loss  of  heat  will  steadily  continue,  until,  after  a  certain  time,  the 
temperature  of  the  heated  body  has  become  reduced  to  that  of  the 
surrounding  atmosphere.  It  then  remains  stationary  at  this  point, 
unless  the  temperature  of  the  atmosphere  should  happen  to  rise  or 
fall ;  in  which  case,  a  similar  change  takes  place  in  the  inorganic 
body,  its  temperature  remaining  constant,  or  varying  with  that  of 
the  surrounding  medium. 

With  living  animals,  the  case  is  different.  If  a  thermometer  be 
introduced  into  the  stomach  of  a  dog,  or  placed  under  the  tongue 
of  the  human  subject,  it  will  indicate  a  temperature  of  100°  F.,  very 
nearly,  whatever  may  be  the  condition  of  the  surrounding  atmos- 
phere at  the  time.  This  internal  temperature  is  the  same  in  sum- 
mer and  in  winter.  If  the  individual  upon  whom  the  experiment 
has  been  tried  be  afterward  exposed  to  a  cold  of  zero,  or  even  of  20° 
or  30°  below  zero,  the  thermometer  introduced  into  the  interior  of 
the  body  will  still  stand  at  100°  F.  As  the  body,  during  the  whole 
period  of  its  exposure,  must  have  been  losing  heat  by  radiation  and 
conduction,  like  any  inorganic  mass,  and  has,  notwithstanding,  main- 
tained a  constant  temperature,  it  is  plain  that  a  certain  amount  of 
heat  has  been  generated  in  the  interior  of  the  body  by  means  of  the 
vital  processes,  sufficient  to  compensate  for  the  external  loss.  The 
internal  heat,  so  produced,  is  known  by  the  name  of  vital  or  animal 
heat. 

There  are  two  classes  of  animals  in  which  the  production  of  vital 


ANIMAL    HEAT.  219 

beat  takes  place  with  such  activity  that  their  blood  and  internal 
organs  are  nearly  always  very  much  above  the  external  temperature; 
and  which  are  therefore  called  "warm-blooded  animals."  Tliese  are 
mammalia  and  birds.  Among  the  birds,  some  species,  as  the  gull, 
have  a  temperature  as  low  as  100°  F.;  but  in  most  of  them  it  is 
higher,  sometimes  reaching  as  high  as  110°  or  111°.  In  the  mam- 
malians, to  which  class  man  belongs,  the  animal  temperature  is  never 
far  from  100°.  In  the  seal  and  the  Greenland  whale,  it  has  been 
found  to  be  10-4°;  and  in  the  porpoise,  which  is  an  air-breathing 
animal,  99°.5.  In  the  human  subject  it  is  98°  to  100.°  When  the 
temperature  of  the  air  is  below  this,  the  external  parts  of  the  body, 
being  most  exposed  to  the  cooling  influences  of  radiation  and  con- 
duction, fall  a  little  below  the  standard,  and  may  indicate  a  tempera- 
ture of  97°,  or  even  several  degrees  below  this  point.  Thus,  on  a 
very  cold  day,  the  thinner  and  more  exposed  parts,  such  as  the  nose, 
the  ears,  and  the  ends  of  the  fingers,  may  become  cooled  down  con- 
siderably below  the  standard  temperature,  and  may  even  be  con- 
gealed, if  the  cold  be  severe;  but  the  temperature  of  the  internal 
organs  and  of  the  blood  still  remains  the  same  under  all  ordinary 
exposures. 

If  the  cold  be  so  intense  and  long  continued  as  to  affect  the 
general  temperature  of  the  blood,  it  at  once  becomes  fatal.  It  has 
been  found  that  although  a  warm-blooded  animal  usually  preserves 
its  natural  temperature  when  exposed  to  external  cold,  yet  if  the 
actual  temperature  of  the  blood  become  reduced  by  any  means 
more  than  5°  or  6°  below  its  natural  standard,  death  inevitably 
results.  The  animal,  under  these  circumstances,  gradually  becomes 
torpid  and  insensible,  and  all  the  vital  operations  finally  cease. 
Birds,  accordingly,  whose  natural  temperature  is  about  110°,  die  if 
the  blood  be  cooled  down  to  100°,  which  is  the  natural  temperature 
of  the  mammalia  ;  and  the  mammalians  die  if  their  blood  be  cooled 
down  below  94°  or  95°.  Each  of  these  different  classes  has  there- 
fore a  natural  temperature,  at  which  the  blood  must  be  maintained 
in  order  to  sustain  life;  and  even  the  different  species  of  animals, 
belonging  to  the  same  class,  have  each  a  specific  temperature  which 
is  characteristic  of  them,  and  which  cannot  be  raised  or  lowered,  to 
any  considerable  extent,  without  producing  death. 

While  in  the  birds  and  mammalians,  however,  the  internal  pro- 
duction of  heat  is  so  active,  that  their  temperature  is  nearly  always 
considerably  above  that  of  the  surrounding  media,  and  suffers  but 
little  variation ;  in  reptiles  and  fish,  on  the  other  hand,  its  produc- 


220 


ANIMAL    HEAT. 


tion  is  much  less  rapid,  and  the  temperature  of  their  bodies  differs 
but  little  from  that  of  the  air  or  water  which  they  inhabit.  Birds  and 
mammalians  are  therefore  called  "  warm-blooded,"  and  reptiles  and 
fish  "  cold-blooded"  animals.  There  is,  however,  no  other  distinc- 
tion between  them,  in  this  respect,  than  one  of  degree.  In  reptiles 
and  fish  there  is  also  an  internal  source  of  heat ;  only  this  is  not  so 
active  as  in  the  other  classes.  Even  in  these  animals  a  difierence 
is  usually  found  to  exist  between  the  temperature  of  their  bodies 
and  that  of  the  surrounding  media.  John  Hunter,  Sir  Humphrey 
Davy,  Czermak,  and  others,'  have  found  the  temperature  of  Proteus 
anguinus  to  be  63°.5,  when  that  of  the  air  was  55° A]  that  of  a  frog 
48°,  in  water  at  44°.4 ;  that  of  a  serpent  88°.46,  in  air  at  81°.5  ;  that 
of  a  tortoise  84°,  in  air  at  79°.o ;  and  that  of  fish  to  be  from  1°.7 
to  2°.5  above  that  of  the  surrounding  water. 

The  following  list^  shows  the  mean  temperature  belongmg  to 
animals  of  different  classes  and  species. 


Birds. 


Mammalia.  ■ 


Reptile. 


Fish. 


{ 


Animal. 

Swallow 

Heron 

Raven 

Pigeon 

Fowl 
^  Gull 

Squirrel 

Goat 

Cat 

Hare 

Ox 

Dog 

Man 
L  Ape 

Toad 

Carp 

Tench 


Mean  Temperatdke. 
1110.25 
1110.2 
108O.5 
1070.6 
106O.7 
1000.0 
1050 
1020.5 
1010.3 
1000.4 

990,5 

990.4 

980.6 

950.9 

510.6 

510.25 
520.10 


In  the  invertebrate  animals,  as  a  general  rule,  the  internal  heat 
is  produced  in  too  small  quantity  to  be  readily  estimated.  In  some 
of  the  more  active  kinds,  however,  such  as  insects  and  arachnida, 
it  is  occasionally  generated  with  such  activity  that  it  may  be 
appreciated  by  the  thermometer.  Thus,  the  temperature  of  the 
butterfly,  when  in  a  state  of  excitement,  is  from  5°  to  9°  above 


'  Simon's  Chemistry  of  Man,  Philadelphia  edition,  p.  124. 
2  Ihid.,  pp.  123—126. 


ANIMAL    HEAT.  221 

that  of  the  air ;  and  that  of  the  humble-bee  from  3°  to  10°  higher 
than  the  exterior.  According  to  the  experiments  of  Mr.  Newport/ 
the  interior  of  a  hive  of  bees  may  have  a  temperature  of  48*^.5, 
when  the  external  atmosphere  is  at  34°.5,  even  while  the  insects 
are  quiet;  but  if  they  be  excited,  by  tapping  on  the  outside  of  the 
hive,  it  may  rise  to  102°.  In  all  cases,  while  the  insect  is  at  rest, 
the  temperature  is  very  moderate;  but  if  kept  in  rapid  motion  in 
a  confined  space,  it  may  generate  heat  enough  to  affect  the  thermo- 
meter sensibly,  in  the  course  of  a  few  minutes. 

Even  in  vegetables  a  certain  degree  of  heat-producing  power  is 
occasionally  manifest.  Usually,  the  exposed  surface  of  a  plant  is 
so  extensive  in  proportion  to  its  mass,  that  whatever  caloric  may 
be  generated  is  too  rapidly  lost  by  radiation  and  evaporation,  to  be 
appreciated  by  ordinary  means.  Under  some  circumstances,  how- 
ever, it  may  accumulate  to  such  an  extent  as  to  become  readily 
perceptible.  In  the  process  of  malting,  for  example,  when  a  large 
quantity  of  germinating  grain  is  piled  together  in  a  mass,  its  ele- 
vated temperature  may  be  readily  distinguished,  both  by  the  hand 
and  the  thermometer.  During  the  flowering  process,  also,  an  unu- 
sual evolution  of  heat  takes  place  in  plants.  The  flowers  of  the 
geranium  have  been  found  to  have  a  temperature  of  87°,  while 
that  of  the  air  was  81°;  and  the  thermometer,  placed  in  the  centre 
of  a  clump  of  blossoms  of  arum  cordifolium,  has  been  seen  to  rise 
to  111°,  and  even  121°,  while  the  temperature  of  the  external  air 
was  only  66°.^ 

Dutroctzet  has  moreover  found,  by  a  series  of  very  ingenious  and 
delicate  experiments,^  that  nearly  all  parts  of  a  living  plant  gene- 
rate a  certain  amount  of  heat.  The  proper  beat  of  the  plant  is 
usually  so  rapidly  dissipated  by  the  continuous  evaporation  of  its 
fluids,  that  it  is  mostly  imperceptible  by  ordinary  means ;  but  if 
this  evaporation  be  prevented,  by  keeping  the  air  charged  with 
watery  vapor,  tbe  heat  becomes  sensible  and  can  be  appreciated  by 
a  delicate  thermometer.  Dutrochet  used  for  this  purpose  a  thermo- 
electric apparatus,  so  constructed  that  an  elevation  of  temperature 
of  1°  F.,  in  the  substance  examined,  would  produce  a  deviation  in 
the  needle  of  nearly  nine  degrees.  By  this  means  he  found  that  he 
could  appreciate,  without  difficulty,  the  proper  temperature  of  the 
plant.     A  certain  amount  of  heat  was  constantly  generated,  during 

'  Carpenter's  General  and  Comparative  Physiology,  Philadelphia,  1851,  p,  852, 

*  Carpenter's  Gen,  and  Comp.  Physiology,  p,  846. 

'  Annales  des  Sciences  Naturelles,  2d  series,  xii,  p.  277. 


222  ANIMAL    HEAT. 

the  day,  in  the  green  stems,  the  leaves,  the  buds,  and  even  the 
roots  and  fruit.  The  maximum  temperature  of  these  parts,  above 
that  of  the  surrounding  atmosphere,  was  sometimes  a  little  over 
one-half  a  degree,  Fahrenheit;  though  it  was  often  considerably 
less  than  this. 

The  different  parts  of  the  vegetable  fabric,  therefore,  generate 
different  quantities  of  caloric.  In  the  same  manner,  the  heat-pro- 
ducing power  is  not  equally  active  in  different  species  of  animals ; 
but  its  existence  is  nevertheless  common  to  both  animals  and  vege- 
tables. 

With  regard  to  the  mode  of  generation  of  this  internal  or  vital 
heat,  we  may  start  with  the  assertion  that  its  production  depends 
upon  changes  of  a  chemical  nature,  and  is  so  far  to  be  regarded  as 
a  chemical  phenomenon.  The  sources  of  heat  which  we  meet  with 
in  external  nature  are  of  various  kinds.  Sometimes  the  heat  is  of 
a  physical  origin ;  as,  for  example,  that  derived  from  the  rays  of 
the  sun,  the  friction  of  solid  substances,  or  the  passage  of  electric 
currents.  In  other  instances  it  is  produced  by  chemical  changes ; 
and  the  most  abundant  and  useful  source  of  artificial  heat  is  the 
oxidation,  or  combustion,  of  carbon  and  carbonaceous  compounds. 
Wood  and  coal,  substances  rich  in  carbon,  are  mostly  used  for  this 
purpose ;  and  charcoal,  which  is  nearly  pure  carbon,  is  frequently 
employed  by  itself.  These  substances,  when  burnt,  or  oxidized, 
evolve  a  large  amount  of  heat ;  and  produce,  as  the  result  of  their 
oxidation,  carbonic  acid.  In  order  that  the  process  may  go  on,  it 
is  of  course  necessary  that  oxygen,  or  atmospheric  air,  should  have 
free  access  to  the  burning  body;  otherwise  the  combustion  and 
evolution  of  heat  cease,  for  want  of  a  necessary  agent  in  the  chemi- 
cal combination.  In  all  these  instances,  the  quantity  of  heat  gene- 
rated is  in  direct  proportion  to  the  amount  of  oxidation ;  and  may 
be  measured,  either  by  the  quantity  of  carbon  consumed,  or  by  that 
of  carbonic  acid  produced.  It  may  be  made  to  go  on,  also,  either 
rapidly  or  slowly,  according  to  the  abundance  and  purity  in  which 
oxygen  is  supplied  to  the  carbonaceous  substance.  Thus,  if  char- 
coal be  ignited  in  an  atmosphere  of  pure  oxygen,  it  burns  rapidly 
and  violently,  raises  the  temperature  to  a  high  point,  and  is  soon 
entirely  consumed.  On  the  other  hand,  if  it  be  shut  up  in  a  close 
stove,  to  which  the  air  is  admitted  but  slowly,  it  produces  only  a 
slight  elevation  of  temperature,  and  may  require  a  much  longer 
time  for  its  complete  disappearance.  Nevertheless,  for  the  same 
quantity  of  carbon  consumed,  the  amount  of  heat  generated,  and 


ANIMAL    HEAT.  223 

that  of  carbonic  acid  produced,  will  be  equal  in  the  two  cases.  In 
one  instance  we  have  a  rapid  combustion,  in  the  other  a  slow  com- 
bustion ;  the  total  effect  being,  however,  the  same  in  both. 

Such  is  the  mode  in  which  heat  is  commonly  produced  by  artifi- 
cial means.  Its  evolution  is  here  dependent  upon  two  striking 
conditions,  which  are  essential  to  it,  and  by  which  it  is  always 
accompanied,  viz.,  the  consumption  of  oxygen,  and  the  production 
of  carbonic  acid. 

Now,  since  the  two  phenomena  just  mentioned  are  presented 
also  by  the  living  body,  and  since  they  are  accompanied  here,  too, 
by  the  production  of  animal  heat,  it  was  very  natural  to  suppose 
that  in  the  animal  organization,  as  well  as  elsewhere,  the  internal 
heat  must  be  owing  to  an  oxidation  or  combustion  of  carbon. 
According  to  Lavoisier,  the  oxygen  taken  into  the  lungs  was  sup- 
posed to  combine  immediately  with  the  carbon  of  the  pulmonary 
tissues  and  fluids,  producing  carbonic  acid,  and  to  be  at  once  returned 
under  that  form  to  the  atmosphere;  the  same  quantity  of  heat  result- 
ing from  the  above  process  as  would  have  been  produced  by  the 
oxidation  of  a  similar  quantity  of  carbon  in  wood  or  coal.  Accord- 
ingly, he  regarded  the  lungs  as  a  sort  of  stove  or  furnace,  by  which 
the  rest  of  the  body  was  warmed,  through  the  medium  of  the  circu- 
lating blood. 

It  was  soon  found,  however,  that  this  view  was  altogether  erro- 
neous ;  for  the  slightest  examination  shows  that  the  lungs  are  not 
perceptibly  warmer  than  the  rest  of  the  body  ;  and  that  the  heat- 
producing  power,  whatever  it  may  be,  does  not  reside  exclusively 
in  the  pulmonary  tissue.  Furthermore,  subsequent  investigations 
showed  the  following  very  important  facts,  which  we  have  already 
mentioned,  viz.,  that  the  carbonic  acid  is  not  formed  in  the  lungs, 
but  exists  in  the  blood  before  its  arrival  in  the  pulmonary  capilla- 
ries ;  and  that  the  oxygen  of  the  inspired  air,  so  far  from  combining 
with  carbon  in  the  lungs,  is  taken  up  in  solution  by  the  blood- 
globules,  and  carried  away  by  the  current  of  the  general  circulation. 
It  is  evident,  therefore,  that  this  oxidation  or  combustion  of  the 
blood  must  take  place,  if  at  all,  not  in  the  lungs,  but  in  the  capil- 
laries of  the  various  organs  and  tissues  of  the  body. 

Liebig  accordingly  adopted  Lavoisier's  theory  of  the  production 
of  animal  heat,  with  the  above  modification.  He  believed  the  heat 
of  the  animal  body  to  be  produced  by  the  oxidation  or  combustion 
of  certain  elements  of  the  food  while  still  circulating  in  the  blood ; 
these  substances  being  converted  into  carbonic  acid  and  water  by 


224  ANIMAL    HEAT. 

the  oxidation  of  their  carbon  and  hydrogen,  and  immediately  ex- 
pelled from  the  body  without  ever  having  formed  a  part  of  the  solid 
tissues.  He  therefore  divided  the  food  into  two  different  classes  of 
alimentary  substances;  viz.,  1st,  the  nitrogenous  or  plastic  elements^ 
which  are  introduced  in  comparatively  small  quantity,  and  which 
are  to  be  actually  converted  into  the  substance  of  the  tissues,  such  as 
albumen,  muscular  flesh,  &c. ;  and  2d,  the  hydro-carhons  or  respiratory 
elements,  such  as  sugar,  starch,  and  fat;  which,  according  to  his  view, 
are  taken  into  the  blood  solely  to  be  burned,  never  being  assimilated 
or  converted  into  the  tissues,  but  only  oxidized  in  the  circulation, 
and  immediately  expelled,  as  above,  under  the  form  of  carbonic 
acid  and  water.  He  therefore  regardf^d  these  elements  of  the  food 
only  as  so  much  fuel ;  destined  simply  to  maintain  the  heat  of  the 
body,  but  taking  no  part  in  the  proper  function  of  nutrition. 

The  above  theory  of  animal  heat  has  been  very  generally  adopted 
and  acknowledged  by  the  medical  profession  until  within  a  recent 
period.  A  few  years  ago,  however,  some  of  its  deficiencies  and 
inconsistencies  were  pointed  out,  by  Lehmann  in  Germany,  and  by 
Eobin  and  Verdeil  in  France ;  and  since  that  time  it  has  begun  to 
lose  ground  and  give  place  to  a  different  mode  of  explanation,  more 
in  accordance  with  the  present  state  of  physiological  science.  We 
believe  it,  in  fact,  to  be  altogether  erroneous;  and  incapable  of 
explaining,  in  a  satisfactory  manner,  the  phenomena  of  animal  heat, 
as  exhibited  by  the  living  body.  We  shall  now  proceed  to  pass  in 
review  the  principal  objections  to  the  theory  of  combustion,  con- 
sidered as  a  physiological  doctrine. 

I.  It  is  not  at  all  necessary  to  regard  the  evolution  of  heat  as 
dependent  solely  on  direct  oxidation.  This  is  only  one  of  its 
sources,  as  we  see  constantly  in  external  nature.  The  sun's  rays, 
mechanical  friction,  electric  currents,  and  more  particularly  a  great 
variety  of  chemical  actions,  such  as  various  saline  combinations  and 
decompositions,  are  all  capable  of  producing  heat ;  and  even  simple 
solutions,  such  as  the  solution  of  caustic  potass  in  water,  the  mixture 
of  sulphuric  acid  and  water,  or  of  alcohol  and  water,  will  often  pro- 
duce a  very  sensible  elevation  of  temperature.  Now  we  know  that 
in  the  interior  of  the  body  a  thousand  different  actions  of  this 
nature  are  constantly  going  on;  solutions,  combinations  and  decom- 
positions in  endless  variety,  all  of  which,  taken  together,  are  amply 
sufficient  to  account  for  the  production  of  animal  heat,  provided  the 
theory  of  combustion  should  be  found  insufficient  or  improbable. 


ANIMAL    HEAT.  225 

II.  In  vegetables  there  is  an  internal  production  of  heat,  as  well 
as  in  animals;  a  fact  which  has  been  fully  demonstrated  by  the 
experiments  of  Dutrochet  and.  others,  already  described.  In  vege- 
tables, however,  the  absorption  of  oxygen  and  exhalation  of  car- 
bonic acid  do  not  take  place;  excepting,  to  some  extent,  during  the 
night.  On  the  contrary,  the  diurnal  process  in  vegetables,  it  is  well 
known,  is  exactly  the  reverse  of  this.  Under  the  influence  of  the 
solar  light  they  absorb  carbonic  acid  and  exhale  oxygen.  And  it 
is  exceedingly  remarkable  that,  in  Dutrochet's  experiments,  he 
found  that  the  evolution  of  heat  by  plants  was  always  accompanied 
by  the  disappearance  of  carbonic  acid  and  the  exhalation  of  oxygen. 
Plants  which,  in  the  daylight,  exhale  oxygen  and  evolve  heat,  if 
placed  in  the  dark,  immediately  begin  to  absorb  oxygen  and  exhale 
carbonic  acid ;  and,  at  the  same  time,  tbe  evolution  of  heat  is  sus- 
pended. Dutrochet  even  found  that  the  evolution  of  heat  by  plants 
presented  a  regular  diurnal  variation;  and  that  its  maximum  of 
intensity  was  aboilt  the  middle  of  the  day,  just  at  the  time  when  the 
absorption  of  carbonic  acid  and  the  exhalation  of  oxygen  are  going  on 
with  the  greatest  activity.  The  proper  heat  of  plants,  therefore,  can- 
not be  the  result  of  oxidation  or  combustion,  but  must  be  dependent 
on  an  entirely  different  process. 

* 

III.  In  animals,  the  quantities  of  oxygen  absorbed  and  of 
carbonic  acid  exhaled  do  not  correspond  with  each  other.  Most 
frequently  a  certain  amount  of  oxygen  disappears  in  the  body,  over 
and  above  that  which  is  returned  in  the  breath  under  the  form  of 
carbonic  acid.  This  overplus  of  oxygen  has  been  said  to  unite  with 
the  hydrogen  of  the  food,  so  as  to  form  water  which  also  passes  out 
by  the  lungs ;  but  this  is  a  pure  assumption,  resting  on  no  direct 
evidence  whatever,  for  we  have  no  experimental  proof  that  any 
more  watery  vapor  is  exhaled  from  the  lungs  than  is  supplied  by 
the  fluids  taken  into  the  stomach.  It  is  superfluous,  therefore,  to 
assume  that  any  of  it  is  produced  by  the  oxidation  of  hydrogen. 

Furthermore,  the  proportion  of  overplus  oxygen  which  disap- 
pears in  the  body,  beside  that  which  is  exhaled  in  the  carbonic  acid 
of  the  breath,  varies  greatly  in  the  same  animal  according  to  the 
quality  of  the  food.  Eegnault  and  Eeiset'  found  that  in  dogs,  fed 
on  meat,  the  oxygen  which  reappeared  under  the  form  of  carbonic 
acid  was  only  75  per  cent,  of  the  whole  quantity  absorbed ;  while 

'   Aiinales  de  Chiiiiie  et  de  Physique,  3d  series,  xxvi.  p.  428. 
15 


226  AXIMAL    HEAT. 

in  dogs  fed  on  vegetable  substances  it  amounted  to  over  90  per 
cent.  In  some  instances/  where  the  animals  (rabbits  and  fowls) 
were  fed  on  bread  and  grain  exclusively,  the  proportion  of  expired 
oxygen  amounted  to  101  or  even  102  per  cent.;  that  is,  more  oxygen 
luas  actually  contaiyied  in  the  carbonic  acid  exhaled,  than  had  been  ab- 
sorbed in  a  free  state  from  the  atmosphere.  A  portion,  at  least,  of  the 
carbonic  acid  must  therefore  have  been  produced  by  other  means 
than  direct  oxidation. 

TV.  It  has  already  been  shown,  in  a  previous  chapter,  that  the 
carbonic  acid  which  is  exhaled  from  the  lungs  is  not  primarily 
formed  in  the  blood,  but  makes  its  appearance  in  the  substance  of 
the  tissues  themselves ;  and  furthermore,  that  even  here  it  does  not 
originate  by  a  direct  oxidation,  but  rather  by  a  process  of  decom- 
position, similar  to  that  by  which  sugar,  in  fermentation,  is  resolved 
into  alcohol  and  carbonic  acid.  We  understand  from  this  how  to 
explain  the  singular  fact  alluded  to  in  the  last  paragraph,  viz.,  the 
abundant  production  of  carbonic  acid,  under  some  circumstances, 
with  a  comparatively  small  supply  of  free  oxygen.  The  statement 
made  by  Liebig,  therefore,  that  starchy  and  oily  matters  taken  with 
the  food  are  immediately  oxidized  in  the  circulation  without  ever 
being  assimilated  by  the  tissues,  is  without  foundation.  It  never, 
in  fact,  rested  on  any  other  ground  than  a  supposed  probability; 
and  as  we  see  that  carbonic  acid  is  abundantly  produced  in  the 
body  by  other  means,  we  have  no  longer  any  reason  for  assuming, 
without  direct  evidence,  the  existence  of  a  combustive  process  in 
the  blood. 

V.  The  evolution  of  heat  in  the  animal  body  is  not  general,  as  it 
would  be  if  it  resulted  from  a  combustion  of  the  blood ;  but  local, 
since  it  takes  place  primarily  in  the  substance  of  the  tissues  them- 
selves. Various  causes  will  therefore  produce  a  local  elevation  or 
depression  of  temperature,  by  modifying  the  nutritive  changes 
which  take  place  in  the  tissues.  Thus,  in  the  celebrated  experiment 
of  Bernard,  which  we  have  often  verified,  division  of  the  sympa- 
thetic nerve  in  the  middle  of  the  neck  produces  very  soon  a  marked 
elevation  of  temperature  in  the  corresponding  side  of  the  head  and 
face.  Local  inflammations,  also,  increase  very  sensibly  the  tempera- 
ture of  the  part  in  which  they  are  seated,  while  that  of  the  general 

'  Annales  de  Chimie  et  de  Physique,  3d  series,  xxvi.  pp.  409 — 451. 


ANIMAL    HEAT.  227 

mass  of  the  blood  is  not  altered.  Finally  it  has  been  demonstrated 
by  Bernard  that  in  the  natural  state  of  the  system  there  is  a  marked 
difference  in  the  temperature  of  the  dififerent  organs  and  of  the  blood 
returning  from  them.*  The  method  adopted  by  this  experimenter 
was  to  introduce,  in  the  living  animal,  the  bulb  of  a  fine  thermo- 
meter successively  into  the  bloodvessels  entering  and  those  leaving 
the  various  internal  organs.  The  difference  of  temperature  in  these 
two  situations  showed  whether  the  blood  had  lost  or  gained  in  heat 
Avhile  traversing  the  capillaries  of  the  organ.  Bernard  found,  in 
the  first  place,  that  the  blood  in  passing  through  the  lungs,  so  far 
from  increasing,  was  absolutely  diminished  in  temperature;  the 
blood  on  the  left  side  of  the  heart  being  sometimes  a  little  more 
and  sometimes  a  little  less  than  one-third  of  a  degree  Fahr.  lower 
than  on  the  right  side.  This  slight  cooling  of  the  blood  in  the 
lungs  is  owing  simply  to  its  exposure  to  the  air  through  the  pul- 
monary membrane,  and  to  the  vaporization  of  water  which  takes 
place  in  these  organs.  In  the  abdominal  viscera,  on  the  contrary, 
the  blood  is  increased  in  temperature.  It  is  sensibly  warmer  in  the 
portal  vein  than  in  the  aorta ;  and  very  considerably  warmer  in  the 
hepatic  vein  than  in  either  the  portal  or  the  vena  cava.  The  blood 
of  the  hepatic  vein  is  in  fact  warmer  than  that  of  any  other  part 
of  the  body.  The  production  of  heat,  therefore,  according  to  Ber- 
nard's observations,  is  more  active  in  the  liver  than  in  any  other 
portion  of  the  system.  As  the  chemical  processes  of  nutrition  are 
necessarily  different  in  the  different  tissues  and  organs,  it  is  easy  to 
understand  why  a  specific  amount  of  heat  should  be  produced  in 
each  of  them.  A  similar  fact,  it  will  be  recollected,  was  noticed  by 
Dutrochet,  in  regard  to  the  different  parts  of  the  vegetable  organ- 
ization. 

VI.  Animal  heat  has  been  supposed  to  stand  in  a  special  relation 
to  the  production  of  carbonic  acid,  because  in  warm-blooded  animals 
the  respiratory  process  is  more  active  than  in  those  of  a  lower 
temperature;  and  because,  in  the  same  animal,  an  increase  or 
diminution  in  the  evolution  of  heat  is  accompanied  by  a  corre- 
sponding increase  or  diminution  in  the  products  of  respiration. 
But  this  is  also  true  of  all  the  other  excretory  products  of  the  body. 
An  elevation  of  temperature  is  accompanied  by  an  increased  activity 
of  all  the  nutritive  processes.     Not  only  carbonic  acid,  but  the 

'  Gazette  Hebdomadaiie,  Aug.  29  and  Sept.  26,  1856. 


228  ANIMAL    HEAT. 

ingredients  of  the  urine  and  the  perspiration  are  discharged  in  larger 
quantity  than  usual.  An  increased  supply  of  food  also  is  required, 
as  well  as  a  larger  quantity  of  oxygen;  and  the  digestive  and 
secretory  processes  both  go  on,  at  the  same  time,  with  unusual 
activity. 

Animal  heat,  then,  is  a  phenomenon  which  results  from  the 
simultaneous  activity  of  many  different  processes,  taking  place  in 
many  different  organs,  and  dependent,  undoubtedly,  on  different 
chemical  changes  in  each  one.  The  introduction  of  oxygen  and 
the  exhalation  of  carbonic  acid  have  no  direct  connection  with  each 
other,  but  are  only  the  beginning  and  the  end  of  a  long  series  of 
continuous  changes,  in  which  all  the  tissues  of  the  body  successively 
take  a  part.  Their  relation  is  precisely  that  which  exists  between 
the  food  introduced  through  the  stomach,  and  the  urinary  ingre- 
dients eliminated  by  the  kidneys.  The  tissues  require  for  their 
nutrition  a  constant  supply  of  solid  and  liquid  food  which  is  intro- 
duced through  the  stomach,  and  of  oxygen  which  is  introduced 
through  the  lungs.  The  disintegration  and  decomposition  of  the 
tissues  give  rise,  on  the  one  hand,  to  urea,  uric  acid,  &c.,  which  are 
discharged  with  the  urine,  and  on  the  other  hand  to  carbonic  acid, 
which  is  exhaled  from  the  lungs.  But  the  oxygen  is  not  directly 
converted  into  carbonic  acid,  any  more  than  the  food  is  directly 
converted  into  urea  and  the  urates. 

Animal  heat  is  not  to  be  regarded,  therefore,  as  the  result  of  a 
combustive  process.  There  is  no  reason  for  believing  that  the 
greater  part  of  the  food  is  "  burned"  in  the  circulation.  It  is,  on 
the  contrary,  assimilated  by  the  substance  of  the  tissues;  and  these, 
in  their  subsequent  disintegration,  give  rise  to  several  excretory 
products,  one  of  which  is  carbonic  acid. 

The  numerous  combinations  and  decompositions  which  follow 
each  other  incessantly  during  the  nutritive  process,  result  in  the 
production  of  an  internal  or  vital  heat,  which  is  present  in  both 
animals  and  vegetables,  and  which  varies  in  amount  in  different 
species,  in  the  same  individual  at  different  times,  and  even  in 
different  parts  and  organs  of  the  same  body. 


THE    CIRCULATION".  229 


CHAPTER    XIV. 

THE    CIRCULATION. 

The  blood  may  be  regarded  as  a  nutritious  fluid,  holding  in 
solution  all  the  ingredients  necessary  for  the  formation  of  the 
tissues.  In  some  animals  and  vegetables,  of  the  lowest  organization, 
such  as  infusoria,  polypes,  algte,  and  the  like,  neither  blood  nor 
circulation  is  required  ;  since  all  parts  of  the  body,  having  a  similar 
structure,  absorb  nourishment  equally  from  the  surrounding  media, 
and  carry  on  nearly  or  quite  the  same  chemical  processes  of  growth 
and  assimilation.  In  the  higher  animals  and  vegetables,  however, 
as  well  as  in  the  human  subject,  the  case  is  different.  In  them,  the 
structure  of  the  body  is  compound.  Different  organs,  with  widely 
different  functions,  are  situated  in  different  parts  of  the  frame ;  and 
each  of  these  functions  is  more  or  less  essential  to  the  continued 
existence  of  the  whole.  In  the  intestine,  for  example,  the  process 
of  digestion  takes  place ;  and  the  prepared  ingredients  of  the  food 
are  thence  absorbed  into  the  bloodvessels,  by  which  they  are 
transported  to  distant  tissues  and  organs.  In  the  lungs,  again, 
the  blood  absorbs  oxygen  which  is  afterward  to  be  appropriated  by 
the  tissues;  and  carbonic  acid,  which  was  produced  in  the  tissues, 
is  exhaled  from  the  lungs.  In  the  liver,  the  kidneys,  and  the  skin, 
other  substances  again  are  produced  or  eliminated,  and  these  local 
processes  are  all  of  them  necessary  to  the  preservation  of  the  general 
organization.  The  circulating  fluid  is  therefore,  in  the  higher 
animals,  a  means  of  transportation,  by  which  the  substances  pror 
duced  in  particular  organs  are  dispersed  throughout  the  body,  or 
by  which  substances  produced  generally  in  the  tissues  are  conveyed 
to  particular  organs,  in  order  to  be  eliminated  and  expelled. 

The  circulatory  apparatus  consists  of  four  different  parts,  viz: 
1st.  The  heart ;  a  hollow,  muscular  organ,  which  receives  the  blood 
at  one  orifice  and  drives  it  out,  in  successive  impulses,  at  another. 
2d.  The  arteries ;  a  series  of  branching  tubes,  which  convey  the 
blood  from  the  heart  to  the  different  tissues  and  organs  of  the  body. 


230 


THE    CIRCULATION'. 


3d.  The  capillaries;  a  network  of  minute  inosculating  tubules, 
whicli  are  interwoven  with  the  substance  of  the  tissues,  and  which 
bring  the  blood  into  intimate  contact  with  the  cells  and  fibres  of 
which  thej  are  composed;  and,  4th.  The  veins;  a  set  of  converg- 
ing vessels,  destined  to  collect  the  blood  from  the  capillaries,  and 
return  it  to  the  heart.  In  each  of  these  four  different  parts  of  the 
circulatory  apparatus,  the  movement  of  the  blood  is  peculiar  and 
dependent  on  special  conditions.  It  will  therefore  require  to  be 
studied  in  each  one  of  them  separately. 


THE   HEART. 


The  structure  of  the  heart,  and  of  the  large  vessels  connected 
with  it,  varies  considerably  in  different  classes  of  animals,  owing  to 
the  different  arrangement  of  the  respiratory  organs.  For  the  respi- 
ratory apparatus  being  one  of  the  most  important  in  the  body,  and 

the  one  most  closely  connected 
•^'S*  '^^'  by  anatomical    relations   with 

the  organs  of  circulation,  the 
latter  are  necessarily  modified 
in  structure  to  correspond  with 
the  former.  In  fish,  for  exam- 
ple (Fig.  76),  the  heart  is  an 
organ  consisting  of  two  princi- 
pal cavities :  an  auricle  (a)  into 
which  the  blood  is  received  from 
the  central  extremity  of  the 
vena  cava,  and  a  ventricle  (b) 
into  which  the  blood  is  driven 
by  the  contraction  of  the  auricle. 
The  ventricle  is  considerably 
larger  and  more  powerful  than 
the  auricle,  and  by  its  contrac- 
tion drives  the  blood  into  the 
main  artery  supplying  the  gills. 
In  the  gills  (cc)  the  blood  is 
arterialized ;  after  which  it  is 
collected  by  the  branchial  veins. 
These  veins  unite  upon  the  median  line  to  form  the  aorta  {d)  by 
which  the  blood  is  finally  distributed  throughout  the  frame.     In 


Circulation-    of    Fish. — a.    Auricle,     b. 
Ventricle,     cc.  Gills,     d.  Aorta,     ee.  Vense  carse. 


THE    HEART. 


231 


Fig.  77. 


these  animals  the  respiratory  process  is  not  a  very  active  one;  but 
the  gills,  which  are  of  small  size,  being  the  only  respiratory  organs, 
all  the  blood  requires  to  pass  through  them  for  purposes  of  aeration. 
The  heart  here  is  a  single  organ,  destined  only  to  drive  the  blood 
from  the  termination  of  the  venous  system  to  the  capillaries  of  the 
gills. 

In  reptiles,  the  heart  is  composed  of  two  auricles,  placed  side  by 
side,  and  one  ventricle.  (B'ig.  77.)  The  venas  cavas  discharge  their 
blood  into  the  right  auricle  (a), 
whence  it  passes  into  the  ventricle 
(c).  From  the  ventricle,  a  part  of  it 
is  carried  into  the  aorta  and  distri- 
buted throughout  the  body,  while  a 
part  is  sent  to  the  lungs  through  the 
pulmonary  artery.  The  arterialized 
blood,  returning  from  the  lungs  by 
the  pulmonary  vein,  is  discharged 
into  the  left  auricle  (6),  and  thence 
into  the  ventricle  (c),  where  it 
mingles  with  the  venous  blood 
which  has  just  arrived  by  the  venae 
cavae.  In  the  reptile,  therefore,  the 
ventricle  is  a  common  organ  of  pro- 
pulsion, both  for  the  lungs  and  for 
the  general  circulation.  In  these 
animals  the  aeration  of  the  blood  in 
the  lungs  is  only  partial ;  a  certain 
portion  of  the  blood  which  leaves 
the  heart  being  carried  to  these  organs,  just  as  in  the  human  subject, 
it  is  only  a  portion  of  the  blood  which  is  carried  to  the  kidney  by 
the  renal  artery.  This  arrangement  is  sufficient  for  the  reptiles, 
because  in  many  of  them,  such  as  serpents  and  turtles,  the  lungs 
are  much  more  extensive  and  efficient,  as  respiratory  organs,  than 
the  gills  of  fish ;  while  in  others,  such  as  frogs  and  water-lizards, 
the  integument  itself,  which  is  moist,  smooth,  and  naked,  takes  an 
important  share  in  the  aeration  of  the  blood. 

In  quadrupeds  and  the  human  species,  however,  'the  respi- 
ratory process  is  not  only  exceedingly  active,  but  the  lungs 
are,  at  the  same  time,  the  only  organs  in  which  the  aeration  of 
the  blood  can  be  fully  accomplished.  In  them,  accordingly,  we 
find    the   two    circulations,   general  and    pulmonary,  entirely  dis- 


ClRCITLATIOX     OF      REPTILES.  —    a. 

Right  auricle.    6.  Left  auricle,    c.  Ventricle. 
d.  Lungs,    e.  Aorta,   f.  Vena  Cava. 


232 


THE    CIRCULATION. 


tinct  from  each  other.  (Fig.  78.)     All  the  blood  returning  from 
the  body  by  the  veins  must  pass  through  the  lungs  before  it  is 

again  distributed  through  the 
Fig-  78.  arterial   system.     We   have 

therefore  a  double  circula- 
tion, and  also  a  double  heart ; 
the  two  sides  of  which, 
though  united  externally, 
are  separate  internally.  The 
mammalian  heart  consists  of 
a  right  auricle  and  ventricle 
((7,  h),  receiving  the  blood 
from  the  vena  cava  (?"),  and 
driving  it  to  the  lungs  ;  and 
a  left  auricle  and  ventricle 
(/,  g)  receiving  the  blood 
from  the  lungs  and  driving 
it  outward  through  the  arte- 
rial system. 

In  the  complete  or  double 
mammalian  heart,  the  differ- 
ent parts  of  the  organ  present 
certain  peculiarities  and  bear 
certain  relations  to  each  other,  which  it  is  necessary  to  understand 
before  we  can  properly  appreciate  its  action  and  movements.  The 
entire  organ  has  a  more  or  less  conical  form,  its  base  being  situated 
on  the  median  line,  directed  upward  and  backward ;  the  whole  being 
suspended  in  the  chest,  and  loosely  fixed  to  the  spinal  column,  by 
the  great  vessels  which  enter  and  leave  it  at  this  point.  The  apex, 
on  the  contrary,  is  directed  downward,  forward,  and  to  the  left,  sur- 
rounded by  the  pericardium  and  the  pericardial  fluid,  but  capable 
of  a  very  free  lateral  and  rotatory  motion.  The  auricles,  which 
have  a  smaller  capacity  and  thinner  walls^  than  the  ventricles,  are 
situated  at  the  upper  and  posterior  part  of  the  organ  (Figs.  79  and 
80);  while  the  ventricles  occupy  its  anterior  and  lower  portions. 
The  two  ventricles,  moreover,  are  not  situated  on  the  same  plane, 
but  the  right  ventricle  occupies  a  position  somewhat  in  front  and 
above  that  of  the  left ;  so  that  in  an  anterior  view  of  the  heart  the 
greater  portion  of  the  left  ventricle  is  concealed  by  the  right  (Fig. 
79),  and  in  a  posterior  view  the  greater  portion  of  the  right  ven- 
tricle is  concealed  by  the  left  (Fig.  80);  while  in  both  positions  the 


Circulation  in  Mammalians. —  a.  Right 
auricle.  6.  Eight  ventricle,  c.  Pulmonary  artery. 
d.  Lungs,  e.  Pulmonary  vein.  /  Left  auricle,  g. 
Left  ventricle,     h.  Aorta,    i.  Vena  cava. 


THE    HEART. 


233 


apex  of  tlie  heart  is  constituted  altogether  by  the  point  of  the  left 
ventricle. 

Fig.  80. 


Human  Heart,  anterior  view. — 
a.  Right  ventricle,  b.  Left  ventricle. 
c.  Right  auricle,  d.  Left  auricle,  e. 
Pulmonary  artery.    /.  Aorta. 


Human  Heart,  posterior  view. — 
a.  Right  ventricle,  b.  Left  ventricle. 
c.  Right  auricle,    d.  Left  auricle. 


The  different  cavities  of  the  heart  and  of  the  adjacent  blood- 
vessels, though  continuous  with  each  other,  are  partially  separated 
by  certain  constrictions.  These  constricted  orifices,  by  which  the 
different  cavities  communicate,  are  known  by  the  names  of  the 

Fig,  81. 


RiOHT  Auricle   and  Ventricle;  Auriculo-ventricular  Valves  open.  Arterial  Valves  closed. 

auricular,  auriculo-ventricular,  and  aortic  and  pulmonary  orifices; 
the  auricular  orifices  being  the  passages  from  the  vense  cavas  and 


234 


THE    CIRCULATION. 


pulmonary  veins  into  the  right  and  left  auricles;  the  auriculo- 
ventricular  orifices  leading  from  the  auricles  into  the  ventricles; 
and  the  aortic  and  pulmonary  orifices  leading  from  the  ventricles 
into  the  aortic  and  pulmonary  arteries  respectively. 

The  auriculo-ventricular,  aortic,  and  pulmonary  orifices  are  fur- 
nished with  valves,  which  allow  the  blood  to  pass  readily  from  the 
auricles  to  the  ventricles,  and  from  the  ventricles  to  the  arteries, 
but  shut  back  with  the  contractions  of  the  organ,  so  as  to  prevent 
its  return  in  an  opposite  direction.  The  course  of  the  blood 
through  the  heart  is,  therefore,  as  follows.  From  the  vena  cava  it 
passes  into  the  right  auricle;  and  from  the  right  auricle  into  the 
right  ventricle.  (Fig.  81.)  On  the  contraction  of  the  right  ventricle, 
the  tricuspid  valves  shut  back,  preventing  its  return  into  the  auricle 
(Fig.  82);  and  it  is  thus  driven  through  the  pulmonary  artery  to  the 


Fig.  82. 


Eight   Auricle  and  Ventricle;   Auriculo-ventricular  Valves  closed,  Arterial  Valves  open. 

lungs.  Returning  from  the  lungs,  it  enters  the  left  auricle,  thence 
passes  into  the  left  ventricle,  from  which  it  is  finally  delivered  into 
the  aorta,  and  distributed  throughout  the  body.  (Fig.  83.)  This 
movement  of  the  blood,  however,  through  the  cardiac  cavities,  is 
not  a  continuous  and  steady  flow,  but  is  accomplished  by  alternate 
contractions  and  relaxations  of  the  muscular  parietes-of  the  heart; 
so  that  with  every  impulse,  successive  portions  of  blood  are  received 
by  the  auricles,  delivered  into  the  ventricles,  and  by  them  dis- 


THE    HEART.  235 

charged  into  the  arteries.     Each  one  of  these  successive  actions  is 
called  a  beat,  or  pulsation  of  the  heart. 

Fig.  83. 


Course   op    Blood   through   the    Heart. — a,  a.   Vena  cava,  superior  and  inferior. 
b.  Right  ventricle,     c.  Pulmonary  artery,     d.  Pulmonary  vein.    e.  Left  ventricle.    /.  Aorta. 

Each  pulsation  of  the  heart  is  accompanied  by  certain  important 
phenomena,  which  require  to  be  studied  in  detail.  These  are  the 
sounds,  the  movements,  and  the  impulse. 

The  sounds  of  the  heart  are  two  in  number.  They  can  readily  be 
heard  by  applying  the  ear  ov,er  the  cardiac  region,  when  they  are 
found  to  be  quite  different  from  each  other  in  position,  in  tone,  and 
in  duration.  They  are  distinguished  as  the  first  and  second  sounds 
of  the  heart.  The  first  sound  is  heard  with  the  greatest  intensity 
over  the  anterior  surface  of  the  heart,  and  more  particularly  over 
the  fifth  rib  and  the  fifth  intercostal  space.  It  is  long,  dull,  and 
smothered  in  tone,  and  occupies  one-half  the  entire  duration  of  a 
single  beat.  It  corresponds  in  time  with  the  impulse  of  the  heart 
in  the  precordial  region,  and  the  stroke  of  the  large  arteries  in  the 
immediate  vicinity  of  the  chest.  The  second  sound  follows  imme- 
diately upon  the  first.  It  is  heard  most  distinctly  at  the  situation 
of  the  aortic  and  pulmonary  valves,  viz.,  over  the  sternum  at  the 
level  of  the  third  costal  cartilage.  It  is  short,  sharp,  and  distinct 
in  tone,  and  occupies  only  about  one-quarter  of  the  whole  time  of 


236  THE    CIRCULATION. 

a  pulsation.  It  is  followed  by  an  equal  interval  of  silence ;  after 
wliich  the  first  sound  again  recurs.  The  whole  time  of  a  cardiac 
pulsation  may  then  be  divided  into  four  quarters,  of  which  the  first 
two  are  occupied  by  the  first  sound,  the  third  by  the  second  sound, 
and  the  fourth  by  an  interval  of  silence,  as  follows : — 


Time  of  pulsation. 


'  1st  quarter  \ 
n ,         „       V  First  sound. 

3d         "  Second  sound. 

4th        "  Interval  of  silence. 


The  cause  of  the  second  sound  is  universally  acknowledged  to  be 
the  sudden  closure  and  tension  of  the  aortic  and  pulmonary  valves. 
This  fact  is  established  by  the  following  proofs :  1st,  this  sound  is 
heard  with  perfect  distinctness,  as  we  have  already  mentioned,  di- 
rectly over  the  situation  of  the  above-mentioned  valves;  2d,  the  far- 
ther we  recede  in  any  direction  from  this  point,  the  fainter  becomes 
the  sound ;  and  3d,  in  experiments  upon  the  living  animal,  often 
repeated  by  different  observers,  it  has  been  found  that  if  a  curved 
needle  be  introduced  into  the  base  of  the  large  vessels,  so  as  to  hook 
back  the  semilunar  valves,  the  second  sound  at  once  disappears, 
and  remains  absent  until  the  valve  is  again  liberated.  These  valves 
consist  of  fibrous  sheets,  covered  with  a  layer  of  endocardial  epithe- 
lium. They  have  the  form  of  semilunar  festoons,  the  free  edge  of 
which  is  directed  away  from  the  cavity  of  the  ventricle,  while  the 
attached  edge  is  fastened  to  the  inner  surface  of  the  base  of  the 
artery.  While  the  blood  is  passing  from  the  ventricle  to  the  artery, 
these  valves  are  thrown  forward  and  relaxed ;  but  when  the  artery 
reacts  upon  its  contents  they  shut  back,  and  their  fibres,  becoming 
suddenly  tense,  yield  a  clear,  characteristic,  snapping  sound. 

The  production  of  the  first  sound  has  been  attributed  by  some 
writers  to  a  combination  of  various  causes ;  such  as  the  rush  of 
blood  through  the  cardiac  orifices,  the  muscular  contraction  of  the 
parietes  of  the  heart,  the  tension  of  the  auriculo-ventricular  valves, 
the  collision  of  the  particles  of  blood  with  each  other  and  with  the 
surface  of  the  ventricle,  &c.  &c.  We  believe,  however,  with  Andry' 
and  some  others,  that  the  first  sound  of  the  heart  has  a  similar 
origin  with  the  second;  and  that  it  is  dependent  altogether  on  the 
closure  of  the  auriculo-ventricular  valves.  The  reasons  for  this  con- 
clusion are  the  following : — 

1st.  The  second  sound  is  undoubtedly  caused  by  the  closure  of 

'  Diseases  of  the  Heart,  Kneeland's  translation,  Boston,  1846. 


THE    HEART.  237 

the  semilunar  valves,  and  in  the  action  of  the  heart  the  shutting 
back  of  the  two  sets  of  valves  alternate  with  each  other  precisely 
as  do  the  first  and  second  sounds;  and  there  is  every  probability, 
to  say  the  least,  that  the  sudden  tension  of  the  valvular  fibres  pro- 
duces a  similar  effect  in  each  instance. 

2d.  The  first  sound  is  heard  most  distinctly  over  the  anterior 
surface  of  the  ventricles,  where  the  tendinous  cords  supporting  the 
auriculo-ventricular  valves  are  inserted,  and  where  the  sound  pro- 
duced by  the  tension  of  these  valves  would  be  most  readily  con- 
ducted to  the  ear. 

8d.  There  is  no  reason  to  believe  that  the  current  of  blood 
through  the  cardiac  orifices  could  give  rise  to  an  appreciable  sound, 
so  long  as  these  orifices,  and  the  cavities  to  which  they  lead,  have 
their  normal  dimensions.  An  unnatural  souffle  may  indeed  origi- 
nate from  this  cause  when  the  orifices  of  the  heart  are  diminished 
in  size,  as  by.  calcareous  or  fibrinous  deposits;  and  it  may  also 
occur  in  cases  of  aneurism.  A  souffle  may  even  be  produced  at 
will  in  any  one  of  the  large  arteries  by  pressing  firmly  upon  it 
with  the  end  of  a  stethoscope,  so  as  to  diminish  its  calibre.  But  in 
all  these  instances,  the  abnormal  sound  occurs  only  in  consequence 
of  a  disturbance  in  the  natural  relation  existing  between  the  volume 
of  the  blood  and  the  size  of  the  orifice  through  which  it  passes. 
In  the  healthy  heart,  tbe  different  orifices  of  the  organ  are  in  exact 
proportion  to  the  quantity  of  the  circulating  blood  ;  and  there  is 
no  more  reason  for  believing  that  its  passage  should  give  rise  to  a 
sound  in  the  cardiac  cavities  than  in  the  larger  arteries  or  veins. 

4:th.  The  difference  in  character  between  the  two  sounds  of  the 
heart  depends,  in  all  probability,  on  the  different  arrangement  of 
the  two  sets  of  valves.  The  second  sound  is  short,  sharp,  and  dis- 
tinct, because  the  semilunar  valves  are  short  and  narrow,  superficial 
in  their  situation,  and  supported  by  the  highly  elastic,  dense  and 
fibrous  bases  of  the  aortic  and  pulmonary  arteries.  The  first  sound 
is  dull  and  prolonged,  because  the  auriculo-ventricular  valves  are 
broad  and  deep-seated,  and  are  attached,  by  their  long  chordas 
tendinese  to  the  comparatively  soft  and  yielding  fleshy  columns  of 
the  heart.  The  difference  between  the  first  and  second  sounds  can, 
in  fact,  be  easily  imitated,  by  simply  snapping  between  the  fingers 
two  pieces  of  tape  or  ribbon,  of  the  same  texture  but  of  different 
lengths.  (Fig.  84.)  The  short  one  will  give  out  a  distinct  and  sharp 
sound ;  the  long  one  a  comparatively  dull  and  prolonged  sound. 

Together  with  the  first  sound  of  the  heart  there  is  also  to  be 


238  THE    CIRCULATION. 

heard  a  sW^i  friction  sound,  produced  by  the  collision  of  the  point 
of  the  heart  against  the  parietes  of  the  chest.  This  sound,  which  is 
heard  in  the  fifth  intercostal  space,  is  very  faint,  and  is  more  or  less 

Fig.  84. 


masked  by  the  strong  valvular  sound  which  occurs  at  the  same 
time.  It  is  different,  however,  in  character  from  the  latter,  and 
may  usually  be  distinguished  from  it  by  careful  examination. 

The  movements  of  the  heart  during  the  time  of  a  pulsation  are 
of  a  peculiar  character,  and  have  been  very  often  erroneously 
described.  In  fact  altogether  the  best  description  of  the  move- 
ments of  the  heart  which  has  yet  appeared,  is  that  given  by  Wil- 
liam Harvey,  in  his  celebrated  work  on  the  Motion  of  the  Heart  and 
Blood,  published  in  1628.  He  examined  the  motion  of  the  heart 
by  opening  the  chest  of  the  living  animal;  and  though  the  same  or 
similar  experiments  have  been  frequently  performed  since  his  time, 
the  descriptions  given  by  subsequent  observers  have  been  for  the 
most  part  singularly  inferior  to  his,  both  in  clearness  and  fidelity. 
The  method  which  we  have  adopted  for  examining  the  motions  of 
the  heart  in  the  dog  is  as  follows:  The  animal  is  first  rendered 
insensible  by  ether,  or  by  the  inoculation  of  woorara.  The  latter 
mode  is  preferable,  since  a  long-continued  etherization  seems  to 
exert  a  sensibly  depressing  effect  on  the  heart's  action,  which  is 
not  the  case  with  woorara.  The  trachea  is  then  exposed  and 
opened  just  below  the  larj'nx,  and  the  nozzle  of  a  bellows  inserted 
and  secured  by  ligature.  Finally,  the  chest  is  opened  on  the  me- 
dian line,  its  two  sides  widely  separated,  so  as  to  expose  the  heart 
and  lungs,  the  pericardium  slit  up  and,  carefull}^  cut  away  from  its 
attachments,  and  the  lungs  inflated  by  insufflation  through  the 
trachea.     By  keeping  up  a  steady  artificial  respiration,  the  move- 


THE    HEART.  239 

ments  of  the  heart  may  be  made  to  continue,  in  favorable  cases,  for 
more  than  an  hour;  and  its  actions  may  be  studied  by  direct  obser- 
vation, like  those  of  any  external  organ. 

The  examination,  however,  requires  to  be  conducted  with  certain 
precautions,  which  are  indispensable  to  success.  When  the  heart 
is  first  exposed,  its  movements  are  so  complicated,  and  recur  with 
such  rapidity,  that  it  is  difficult  to  distinguish  them  perfectly  from 
each  other,  and  to  avoid  a  certain  degree  of  confusion.  Singular 
as  it  may  seem,  it  is  even  difficult  at  first  to  determine  what  period 
in  the  heart's  pulsation  corresponds  to  contraction,  and  what  to 
relaxation  of  the  organ.  We  have  even  seen  several  medical  men, 
watching  together  the  pulsations  of  the  same  heart,  unable  to  agree 
upon  this  point.  It  is  very  evident,  indeed,  that  several  English 
and  continental  observers  have  mistaken,  in  their  examinations,  the 
contraction  for  the  relaxation,  and  the  relaxation  for  the  contrac- 
tion. The  first  point,  therefore,  which  it  is  necessary  to  decide,  in 
examining  the  successive  movements  of  a  cardiac  pulsation,  is  the 
following,  viz:  Which  is  the  contraction  and  which  the  relaxation  of 
the  ventricles?  The  method  which  we  have  adopted  is  to  pass  a 
small  silver  canula  directly  through  the  parietes  of  the  left  ven- 
tricle into  its  cavity.  The  blood  is  then  driven  from  the  external 
orifice  of  the  canula  in  interrupted  jets;  each  jet  indicating  the 
time  at  which  the  ventricle  contracts  upon  its  contents.  The 
canula  is  then  withdrawn,  and  the  difierent  muscular  layers  of  the 
ventricular  walls,  crossing  each  other  obliquely,  close  the  opening, 
so  that  there  is  little  or  no  subsequent  hemorrhage. 

When  the  successive  actions  of  contraction  and  relaxation  have 
by  this  means  been  fairly  recognized  and  distinguished  from  each 
other,  the  cardiac  pulsations  are  seen  to  be  characterized  by  the 
following  phenomena.  The  changes  in  form  and  position  of  the 
entire  heart  are  mainly  dependent  on  those  of  the  ventricles,  which 
contract  simultaneously  with  each  other,  and  which  constitute 
much  the  largest  portion  of  the  entire  mass  of  the  organ. 

1.  At  the  time  of  its  contraction  the  heart  hardens.  This  pheno- 
menon is  exceedingly  well  marked,  and  is  easily  appreciated  by 
placing  the  finger  upon  the  ventricles,  or  by  grasping  them  between 
the  finger  and  thumb.  The  muscular  fibres  become  swollen  and 
indurated,  and  if  grasped  by  the  hand  communicate  the  sensation 
of  a  somewhat  sudden  and  powerful  shock.  It  is  this  forcible  indu- 
ration of  the  heart,  at  the  time  of  contraction,  which  has  been  mis- 
taken by  some  writers  for  an  active  dilatation,  and  described  as 


240  THE    CIRCULATION. 

such.  It  is,  however,  a  phenomenon  precisely  similar  to  that  which 
takes  place  in  the  contraction  of  a  voluntary  muscle,  which  be- 
comes swollen  and  indurated  at  the  same  moment  and  in  the  same 
proportion  that  it  diminishes  in  length, 

2.  At  the  time  of  contraction,  the  ventricles  elongate  and  the 
point  of  the  heart  protrudes.  This  phenomenon  was  very  well 
described  by  Dr.  Harvey.^  "The  heart,"  he  says,  "is  erected,  and 
rises  upward  to  a  point,  so  that  at  this  time  it  strikes  against  the 
breast  and  the  pulse  is  felt  externally."  The  elongation  of  the 
ventricles  during  contraction  has,  however,  been  frequently  denied 
by  subsequent  writers.  The  only  modern  observers,  so  far  as  we 
are  aware,  who  have  recognized  its  existence,  are  Drs.  C.  W.  Pen- 
nock  and  Edward  M.  Moore,  who  performed  a  series  of  very  careful 
and  interesting  experiments  on  the  action  of  the  heart,  in  Philadel- 
phia, in  the  year  1839.^  These  experimenters  operated  upon  calves, 
sheep,  and  horses,  by  stunning  the  animal  with  a  blow  upon  the 
head,  opening  the  chest,  and  keeping  up  artificial  respiration.  They 
observed  an  elongation  of  the  ventricle  at  the  time  of  contraction, 
and  were  even  able  to  measure  its  extent  by  applying  a  shoemaker's 
rule  to  the  heart  while  in  active  motion.  We  are  able  to  corroborate 
entirely  the  statement  of  these  observers  by  the  result  of  our  own 
experiments  on  dogs,  rabbits,  frogs,  &c.  The  ventricular  contrac- 
tion is  an  active  movement,  the  relaxation  entirely  a  passive  one. 
When  contraction  occurs  and  a  stream  of  blood  is  thrown  out  of 
the  ventricle,  its  sides  approximate  each  other  and  its  point  elon- 
gates ;  so  that  the  transverse  diameter  of  the  heart  is  diminished, 
and  its  longitudinal  diameter  increased.  This  can  be  readily  felt 
by  grasping  the  base  of  the  heart  and  the  origin  of  the  large  vessels 
gently  between  the  first  and  middle  fingers,  and  allowing  the  end 
of  the  thumb  of  the  same  hand  to  rest  lightly  upon  its  apex. 
With  every  contraction  the  thumb  is  sensibly  lifted  and  separated 
from  the  fingers,  by  a  somewhat  forcible  elevatiou.of  the  point  of 
the  heart. 

The  same  thing  can  be  seen,  and  even  measured  by  the  eye, 
in  the  following  manner :  If  the  heart  of  the  frog  or  even  of  any 
small  warm-blooded  animal,  as  the  rabbit,  be  rapidly  removed  from 
the  chest,  it  will  continue  to  beat  for  some  minutes  afterward;  and 
when  the  rhythmical  pulsations  have  finally  ceased,  contractions 

'  Works  of  William  Harvey,  M.  D.     Sydenharii  ed.,  Loiulon,  1847,  p.  21. 
'  Philadelphia  Medical  Kxiuiiiuer,   No.  44. 


THE    HEAET. 


241 


can  still  be  readily  excited  by  toucliing  the  heart  with  the  point  of 
a  steel  needle.  If  the  heart  be  now  held  by  its  base  between  the 
thumb  and  finger,  with  its  point  directed  upward,  it  will  be  seen 
to  have  a  pyramidal  or  conical  form,  representing  very  nearly  in 
its  outline  an  equilateral  triangle  (Fig.  85) ;  its  base,  while  in  a 
condition  of  rest,  bulging  out  laterally,  while  the  apex  is  compara- 
tively obtuse. 


Fig.  85. 


Fig.  86. 


Heart  of  Froq 
in  a  state  of  relaxa- 
tion. 


Heart   of    Frog   iu  contiaction. 


When  the  heart,  held  in  this  position,  is  touched  with  the  point 
of  a  needle  (Fig.  86),  it  starts  up,  becomes  instantly  narrower  and 
longer,  its  sides  approximating  and  its  point  rising  to  an  acute 
ancle.  This  contraction  is  immediately  followed  by  a  relaxation ; 
the  point  of  the  heart  sinks  down,  and  its  sides  again  bulge  out- 
ward. 

Let  us  now  see  in  what  manner  this  change  in  the  figure  of  the 
ventricles  during  contraction  is  produced.  If  the  muscular  fibres 
of  the  heart  were  arranged  in  the  form  of 
simple  loops,  running  parallel  with  the 
axis  of  the  organ,  the  contraction  of  these 
fibres  would  merely  have  the  effect  of  di- 
minishing the  size  of  the  heart  in  every 
direction.  This  effect  can  be  seen  in  the 
accompanying  hypothetical  diagram  (Fig. 
87),  where  the  white  outline  represents 
such  simple  looped  fibres  in  a  state  of  re- 
laxation, and  the  dotted  internal  line  indi- 
cates the  form  which  they  would  take  in 
contraction.  In  point  of  fact,  however, 
none  of  the  muscular  fibres  of  the  heart 

run  parallel  to  its  longitudinal  axis.     They  are  disposed,  on  the 
contrary,  in  a  direction  partly  spiral  and  partly  circular.     The  most 
superficial  fibres  start  from  the  base  of  the  ventricles,  and  pass 
16 


Diagram  of  Simple  Looped 
Fibres,  in  relaxation  and  con- 
traction. 


242 


THE    CIRCULATION. 


toward  the  apex,  curling  round  the  heart  in  such  a  manner  as  to 
pass  over  its  anterior  surface  in  an  obliquely  spiral  direction,  from 
above  downward,  and  from  right  to  left.  (Fig.  88.)     They  converge 

toward  the  point  of  the  heart,  curl- 
ing round  the  centre  of  its  apex,  and 
then,  changing  their  direction,  be- 
come deep-seated,  run  upward  along 

Fig.  89. 


Fig.  88. 


Bullock's  Heart,  anterior  view, 
showing  the  superficial  muscular  litres. 


Left  Ventricle  op 
BdLLOCK's  Heart,  show- 
ing the  deep  fibres. 


the  septum  and  internal  surface  of  the  ventricles,  and  terminate 
in  the  columnae  carnese,  and  in  the  inner  border  of  the  auriculo- 
ventricular  ring.  The  deeper  layers  of  fibres,  on  the  contrary,  are 
wrapped  round  the  ventricles  in  a  nearly  circular  direction  (Fig. 
89);  their  points  of  origin  and  attachment  being  still  the  auriculo- 
ventricular  ring,  and  the  points  of  the  fleshy  columns.  The  entire 
arrangement  of  the  muscular  bundles  may  be  readily  seen  in  a 
heart  which  has  been  boiled  for  six  or  eight  hours,  so  as  to  soften 
the  connecting  areolar  tissue,  and  enable  the  fibrous  layers  to  be 
easily  separated  from  each  other. 

By  far  the  greater  part  of  the  mass  of  the  fibres  have  therefore 
a  circular  instead  of  a  longitudinal  direction.  When  they  contract, 
their  action  tends  to  draw  the  lateral  walls  of  the  ventricles  together, 
and  thus  to  diminish  the  transverse  diameter  of  the  heart ;  but  as 
each  muscular  fibre  becomes  thickened  in  direct  proportion  to  its 
contraction,  their  combined  lateral  swelling  necessarily  pushes  out 
the  apex  of  the  ventricle,  and  the  heart  elongates  at  the  same  time 
that  its  sides  are  drawn  together.  This  effect  is  illustrated  in  the 
accompanying  diagram  (Fig.  90),  where  the  white  lines  show  the 
ficrure  of  the  heart  durinor  relaxation,  with  the  course  of  its  circular 


THE    HEART. 


243 


Diagram  of  Circular  Fibres 
OF  THE  Heart,  and  their  con- 
traction. 


fibres,  while  the   dotted  line  shows  the   narrowed  and   elongated 

figure  necessarily  produced  by  their  contraction.   This  phenomenon, 

therefore,  of  the  protrusion  of  the  apex 

of  the  heart  at  the  time  of  contraction,  is 

not  only  fully  established  by  observation, 

but  is  readily  explained  by  the  anatomical 

structure  of  the  organ. 

3.  Simultaneously  with  the  hardening 
and  elongation  of  the  heart,  its  apex  moves 
slightly  from  left  to  right,  and  rotates  also 
upon  its  own  axis  in  the  same  direction. 
Both  these  movements  result  from  the 
peculiar  spiral  arrangement  of  the  cardiac 
fibres.  If  we  refer  again  to  the  preceding 
diagrams,  we  shall  see  that,  provided  the 
fibres  were  arranged  in  simple  longitudi- 
nal loops  (Fig.  87),  their  contraction  would 

merely  have  the  efl[ect  of  drawing  the  point  of  the  heart  directly 
upward  in  a  straight  line  toward  its  base.  On  the  other  hand,  if 
they  were  arranged  altogether  in  a  circular  direction  (Fig.  90),  the 
apex  would  be  simply  protruded  forward,  also  in  a  direct  line, 
without  deviating  or  twisting  either  to  the 
right  or  to  the  left.  But  iu  point  of  fact, 
the  superficial  fibres,  as  we  have  already 
described,  run  spirally,  and  curling  round 
the  point  of  the  heart,  turn  inward  toward 
its  base  ;  so  that  if  the  apex  of  the  organ  be 
viewed  externally,  it  will  be  seen  that  the 
superficial  fibres  converge  toward  its  cen- 
tral point  in  curved  lines,  as  in  Fig.  91.  It 
is  well  known  that  every  curved  muscular 
fibre,  at  the  time  of  its  shortening,  necessa- 
rily approximates  more  or  less  to  a  straight 

line.  Its  curvature  is  diminished  in  exact  proportion  to  the  extent 
of  its  contraction;  and  if  arranged  in  a  spiral  form,  its  contraction 
tends  in  the  same  degree  to  untwist  the  spiral.  During  the  con- 
traction of  the  heart,  therefore,  its  apex  rotates  on  its  own  axis  in 
the  direction  indicated  by  the  arrows  in  Fig.  91,  viz.,  from  left  to 
right  anteriorly,  and  from  right  to  left  posteriorly.  This  produces 
a  twisting  movement  of  the  apex  in  the  above  direction,  which  is 


Fig.  91. 


Converging    Fibres   or 
THE  Apex  of  the  Heart. 


244  THE    CIRCULATION. 

very  perceptible  to  the  eye  at  every  pulsation  of  the  heart,  when 
exposed  in  the  living  animal. 

4.  The  protrusion  of  the  point  of  the  heart  at  the  time  of  con- 
traction, together  with  its  rotation  upon  its  axis  from  left  to  right, 
brings  the  apex  of  the  organ  in  contact  with  the  parietes  of  the 
chest,  and  produces  the  shock  or  impulse  of  the  heart,  which  is 
readily  perceptible  externally,  both  to  the  eye  and  to  the  touch. 
In  the  human  subject,  when  in  an  erect  position,  the  heart  strikes 
the  chest  in  the  fifth  intercostal  space,  midway  between  the  edge  of 
the  sternum  and  a  line  drawn  perpendicularly  downward  from  the 
left  nipple.  In  a  supine  position  of  the  body,  the  heart  falls  away 
from  the  anterior  parietes  of  the  chest  so  much  that  the  impulse  may 
disappear  for  the  time  altogether.  This  alternate  recession  and 
advance  of  the  point  of  the  heart,  in  relaxation  and  contraction, 
is  provided  for  by  the  anatomical  arrangement  of  the  pericardium, 
and  the  existence  of  the  pericardial  fluid.  As  the  heart  plays  back- 
ward and  forward,  the  pericardial  fluid  constantly  follows  its 
movements,  receding  as  the  heart  advances,  and  advancing  as  the 
heart  recedes.  It  fulfils,  in  this  respect,  the  same  purpose  as  the 
synovial  fluid,  and  the  folds  of  adipose  tissue  in  the  cavity  of  the 
large  articulations ;  and  allows  the  cardiac  movements  to  take  place 
to  their  full  extent  without  disturbing  or  injuring  in  any  way  the 
adjacent  organs. 

5.  The  rhythm  of  the  heart's  pulsations  is  peculiar  and  somewhat 
complicated.  Each  pulsation  is  made  up  of  a  double  series  of  con- 
tractions and  relaxations.  The  two  auricles  contract  together,  and 
afterward  the  two  ventricles ;  and  in  each  case  the  contraction  is 
immediately  followed  by  a  relaxation.  The  auricular  contraction 
is  short  and  feeble,  and  occupies  the  first  part  of  the  time  of  a 
pulsation.  The  ventricular  contraction  is  longer  and  more  powerful, 
and  occupies  the  latter  part  of  the  same  period.  Following  the 
ventricular  contraction  there  comes  a  short  interval  of  repose,  after 
which  the  auricular  contraction  again  recurs.  The  auricular  and 
ventricular  contractions,  however,  do  not  alternate  so  distinctly 
with  each  other  (like  the  strokes  of  the  two  pistons  of  a  fire  engine) 
as  we  should  be  led  to  believe  from  the  accounts  which  have  been 
given  by  some  observers.  On  the  contrary,  they  are  connected  and 
continuous.  The  contraction,  which  commences  at  the  auricle,  is 
immediately  propagated  to  the  ventricle,  and  runs  rapidly  from  the 
base  of  the  heart  to  its  apex,  very  much  in  the  manner  of  a  peris- 
taUic  motion,  except  that  it  is  more  sudden  and  vigorous. 


THE    HEAKT.  245 

William  Harvey,  again,  gives  a  better  account  of  this  part  of  the 
heart's  action  than  has  been  published  by  any  subsequent  writer. 
The  following  exceedingly  graphic  and  appropriate  description, 
taken  from  his  book,  shows  that  he  derived  his  knowledge,  not 
from  any  secondary  or  hypothetical  sources,  but  from  direct  and 
careful  study  of  the  phenomena  in  the  living  animal. 

"  First  of  all,"  he  says,'  "  the  auricle  contracts,  and  in  the  course 
of  its  contraction  throws  the  blood  (which  it  contains  in  ample 
quantity  as  the  head  of  the  veins,  the  storehouse  and  cistern  of  the 
blood)  into  the  ventricle,  which  being  filled,  the  heart  raises  itself 
straightway,  makes  all  its  fibres  tense,  contracts  the  ventricles,  and 
performs  a  beat,  by  which  beat  it  immediately  sends  the  blood 
supplied  to  it  by  the  auricle,  into  the  arteries;  the  right  ventricle 
sending  its  charge  into  the  lungs  by  the  vessel  which  is  called  vena 
arteriosa,  but  which,  in  structure  and  function,  and  all  things  else, 
is  an  artery ;  the  left  ventricle  sending  its  charge  into  the  aorta, 
and  through  this  by  the  arteries  to  the  body  at  large. 

"  These  two  motions,  one  of  the  ventricles,  another  of  the  auricles, 
take  place  consecutively,  but  in  such  a  manner  that  there  is  a  kind 
of  harmony  or  rhythm  preserved  between  them,  the  two  concurring 
in  such  wise  that  but  one  motion  is  apparent,  especially  in  the 
warmer  blooded  animals,  in  which  the  movements  in  question  are 
rapid.  Nor  is  this  for  any  other  reason  than  it  is  in  a  piece  of 
machinery,  in  which,  though  one  wheel  gives  motion  to  another, 
yet  all  the  wheels  seem  to  move  simultaneously ;  or  in  that 
mechanical  contrivance  which  is  adapted  to  fire-arms,  where  the 
trigger  being  touched,  down  comes  the  flint,  strikes  against  the 
steel,  elicits  a  spark,  which  falling  among  the  powder,  it  is  ignited, 
upon  which  the  flame  extends,  enters  the  barrel,  causes  the  explo- 
sion, propels  the  ball,  and  the  mark  is  attained ;  all  of  which 
incidents,  by  reason  of  the  celerity  with  which  they  happen,  seem 
to  take  place  in  the  twinkling  of  an  eye." 

The  above  description  indicates  precisely  the  manner  in  which 
the  contraction  of  the  ventricle  follows  successively  and  yet  con- 
tinuously upon  that  of  the  auricle.  The  entire  action  of  the  auricles 
and  ventricles  during  a  pulsation  is  accordingly  as  follows :  The 
contraction  begins,  as  we  have  already  stated,  at  the  auricle. 
Thence  it  runs  immediately  forward  to  the  apex  of  the  heart.  The 
entire  ventricle  contracts  vigorously,  its   walls   harden,  its  apex 

•  Op.  cit.,p.  31. 


246  THE    CIRCULATION. 

protrudes,  strikes  against  the  walls  of  the  chest,  and  twists  from 
left  to  right,  the  auriculo- ventricular  valves  shut  back,  the  first 
sound  is  produced,  and  the  blood  is  driven  into  the  aorta  and 
pulmonary  artery.  These  phenomena  occupy  about  one-half  the 
time  of  an  entire  pulsation.  Then  the  ventricle  is  immediately 
relaxed,  and  a  short  period  of  repose  ensues.  During  this  period 
the  blood  flows  in  a  steady  stream  from  the  large  veins  into  the 
auricle,  and  through  the  auriculo-ventricular  orifice  into  the  ven- 
tricle ;  filling  the  ventricle,  by  a  kind  of  passive  dilatation,  about 
two-thirds  or  three-quarters  full.  Then  the  auricle  contracts  with 
a  quick  sharp  motion,  forces  the  last  drop  of  blood  into  the  ventricle, 
distending  it  to  its  full  capacity,  and  then  the  ventricular  contraction 
follows,  as  above  described,  driving  the  blood  into  the  large  arteries. 
These  movements  of  contraction  and  relaxation  continue  to  alternate 
with  each  other,  and  form,  by  their  recurrence,  the  successive 
cardiac  pulsations. 


THE   ARTERIES   AND   THE   ARTERLAL    CIRCULATION. 

The  arteries  are  a  series  of  branching  tubes  which  commence 
with  the  aorta  and  ramify  throughout  the  body,  distributing  the 
blood  to  all  the  vascular  organs.  They  are  composed  of  three 
coats,  viz :  an  internal  homogeneous  tunic,  continuous  with  the 
endocardium;  a  middle  coat,  composed  of  elastic  and  muscular 
fibres ;  and  an  external  or  "  cellular"  coat,  composed  of  condensed 
layers  of  areolar  tissue.  The  essential  anatomical  difference  be- 
tween tbe  larger  and  the  smaller  arteries  consists  in  the  structure 
of  their  middle  coat.  In  the  smaller  arteries  this  coat  is  composed 
exclusively  of  smooth  muscular  fibres,  arranged  in  a  circular 
manner  around  the  vessel,  like  the  circular  fibres  of  the  muscular 
coat  of  the  intestine.  In  arteries  of  medium  size  the  middle  coat 
contains  both  muscular  and  elastic  fibres;  while  in  those  of  the 
largest  calibre  it  consists  of  elastic  tissue  alone.  The  large  arteries, 
accordingly,  possess  a  remarkable  degree  of  elasticity  and  little  or 
no  contractility  ;  while  the  smaller  are  contractile,  and  but  little  or 
not  at  all  elastic. 

It  is  found,  by  measuring  the  diameters  of  the  successive  arte- 
rial ramifications,  that  the  combined  area  of  all  the  branches  given 
off'  from  a  trunk  is  somewhat  greater  than  that  of  the  original 


THE    ARTERIES    AND    THE    ARTERIAL    CIRCULATION.      247 

vessel;  and  therefore  that  the  combined  area  of  all  the  small 
arteries  must  be  considerably  larger  than  that  of  the  aorta,  from 
which  the  arterial  system  originates.  As  the  blood,  consequently, 
in  its  passage  from  the  heart  outward,  flows  successively  through 
larger  and  larger  spaces,  the  rapidity  of  its  circulation  must  neces- 
sarily be  diminished,  in  the  same  proportion  as  it  recedes  from  the 
heart.  It  is  driven  rapidly  through  the  larger  trunks,  more  slowly 
through  those  of  medium  size,  and  more  slowly  still  as  it  approaches 
the  termination  of  the  arterial  system  and  the  commencement  of 
the  capillaries. 

The  movement  of  the  blood  through  the  arteries  is  primarily  caused 
by  the  contractions  of  the  heart ;  but  is,  at  the  same  time,  regulated 
and  modified  by  the  elasticity  of  the  vessels.  The  mode  in  which 
the  arterial  circulation  takes  place  is  as  follows.  At  the  time  of  the 
heart's  contraction,  the  muscular  walls  of  the  ventricle  act  power- 
fully upon  its  fluid  contents.  The  auriculo- ventricular  valves  at 
the  same  time  shutting  back  and  preventing  the  blood  from  regur- 
gitating into  the  auricle,  it  is  forced  out  through  the  aortic  orifice. 
A  charge  of  blood  is  therefore  driven  into  that  part  of  the  aorta 
nearest  the  heart,  by  which  the  artery  is  distended  in  exact  propor- 
tion to  the  force  of  the  heart's  action  and  the  quantity  of  blood 
which  it  expels.  When  the  ventricle  relaxes,  the  distending  force 
is  removed ;  and  the  elastic  arterial  walls,  reacting  upon  their  con- 
tents, would  force  the  blood  back  again  into  the  heart,  were  it  not 
for  the  semilunar  valves  which  shut  together  and  close  the  aortic 
orifice.  The  column  of  blood  is  accordingly  forced  onward,  into 
the  next  division  of  the  arterial  system,  which  is  distended  in  its 
tufn  and  reacts  again  upon  the  blood,  driving  the  blood  necessarily 
farther  and  farther  from  the  heart,  until  it  arrives  at  the  confines  of 
the  capillary  system.  In  this  manner  a  succession  of  waves  or  im- 
pulses is  propagated  from  the  heart  outward  (Fig.  92),  consisting 
of  the  alternate  distension  and  reaction  of  different  portions  of  the 
artery,  and  which  is  readily  perceptible  whenever  the  vessel  occu- 
pies a  superficial  position.  This  phenomenon  is  known  by  the 
name  of  the  arterial  'pulse. 

When  the  blood  is  thus  driven  by  the  cardiac  pulsations  into  the 
artery,  the  vessel  is  not  only  "distended  laterally,  but  is  elongated 
as  well  as  widened,  and  enlarged  in  every  direction.  Particularly 
when  the  vessel  takes  a  curved  or  serpentine  course,  its  elongation 
and  the  increase  of  its  curvatures  may  be  observed  at  every  pulsa- 


248 


THE    CIECULATIOISr. 


tion.  This  may  be  seen,  for  example,  in  the  temporal  arteries,  or 
even  in  the  radial  arteries,  in  emaciated  persons.  It  is  also  very 
well  seen  in  the  mesenteric  arteries,  when  the  abdomen  is  opened 

Fig.  92. 


Diagram  of  Arterial  Circulation. 


in  the  living  animal.  At  every  contraction  of  the  heart  the  curves 
of  the  artery  on  each  side  become  more  strongly  pronounced.  (Fig. 
93.)  The  vessel  even  rises  up  partially  out  of  its 
bed,  particularly  where  it  runs  over  a  bony  sur- 
face, as  in  the  case  of  the  radial  artery.  In  old 
persons  the  curves  of  the  vessels  become  perma- 
nently enlarged  from  frequent  distension ;  and  all 
the  arteries  tend  to  assume,  with  the  advance  of 
age,  a  more  serpentine  and  even  spiral  course. 

Owing  to  the  alternating  contractions  and  re- 
laxations of  the  heart,  the  blood  passes  through 
the  arteries,  not  in  a  steady  stream,  but,  as  already 
described,  in  a  series  of  welling  impulses;  and 
the  hemorrhage  from  a  wounded  artery  is  readily 
distinguished  from  venous  or  capillary  hemor- 
rhage by  the  fact  that  the  blood  flows  in  suc- 
cessive jets,  as  well  as  more  rapidly  and  abund- 
antly. If  a  puncture  be  made  in  the  walls  of  the 
ventricle,  and  a  slender  canula  introduced,  the  flow  of  the  blood 
through  it  is  seen  to  be  entirely  intermittent.  A  strong  jet  takes 
place  at  each  ventricular  contraction,  and  at  each  relaxation  the 
flow  is  completely  interrupted.  If  the  puncture  be  made,  however, 
in  any  of  the  large  arteries  near  the  heart,  the  flow  of  blood  through 
the  orifice  is  no  longer  intermittent,  but  is  continuous ;  only  it  is 
very  much  stronger  at  the  time  of  ventricular  contraction,  and 
diminishes,  though  it  does  not  entirely  cease,  at  the  time  of  relaxa- 
tion. This  is  on  account  of  the  elasticity  of  the  arterial  coats.  For 
if  the  blood  were  driven  through  a  series  of  perfectly  rigid  and 
unyielding  tubes,  its  flow  would  be  everywhere  intermittent ;  and  it 
would  be  delivered  from  an  orifice  situated  at  any  point,  in  perfectly 


Elungation  and  curva- 
ture of  an  Artert   in 

PULSATION. 


THE    ARTERIES    AND    THE    ARTERIAL    CIRCULATION.      249 

interrupted  jets.  But  the  arteries  are  yielding  and  elastic.  When 
the  contraction  of  the  heart  drives  the  blood  into  the  aorta,  a  part 
of  its  force  is  expended  for  the  time  in  distending  the  walls  of  the 
vessel;  and  this  force  is  returned  to  the  blood,  when  the  heart 
relaxes,  by  the  elastic  reaction  of  the  arterial  coats.  The  interrupted 
or  pulsating  character  of  the  arterial  current,  therefore,  which  is 
strongly  pronounced  in  the  immediate  vicinity  of  the  heart,  becomes 
gradually  lost  and  equalized,  during  its  passage  through  the  vessels, 
until  in  the  smallest  arteries  it  is  nearly  imperceptible. 

The  same  effect  of  an  elastic  medium  in  equalizing  the  force  of 
an  interrupted  current  may  be  shown  by  fitting  to  the  end  of  a 
common  syringe  a  long  glass  or  metallic  tube.  Whatever  be  the 
length  of  the  inelastic  tubing,  the  water  which  is  thrown  into  one 
extremity  of  it  by  the  syringe  will  be  delivered  from  the  other  end 
in  distinct  jets,  corresponding  with  the  strokes  of  the  piston ;  but  if 
the  metallic  tube  be  replaced  by  one  of  India  rubber,  of  sufficient 
length,  the  elasticity  of  this  substance  merges  the  force  of  the  sepa- 
rate impulses  into  each  other,  and  the  water  is  driven  out  from  the 
farther  extremity  in  a  continuous  stream. 

The  elasticity  of  the  arteries,  however,  never  entirely  equalizes 
the  force  of  the  separate  cardiac  pulsations,  since  a  pulsating  cha- 
racter can  be  seen  in  the  flow  of  the  blood  through  even  the  smallest 
arteries,  under  the  microscope;  but  this  pulsating  character  dimin- 
ishes very  considerably  from  the  heart  outward,  and  the  current 
becomes  much  more  continuous  in  the  smaller  vessels  than  in  the 
larger. 

The  primary  cause,  therefore,  of  the  motion  of  the  blood  in  the 
arteries  is  the  contraction  of  the  ventricles,  which,  by  driving  out 
the  blood  in  interrupted  impulses,  distends  at  every  stroke  the 
whole  arterial  system.  But  the  arterial  pulse  is  not  exactly  syn- 
chronous everywhere  with  the  beat  of  the  heart;  since  a  certain 
amount  of  time  is  required  to  propagate  the  blood-wave  from  the 
centre  of  the  circulation  outward.  The  pulse  of  the  radial  artery 
at  the  wrist  is  perceptibly  later  than  that  of  the  heart ;  and  the 
pulse  of  the  posterior  tibial  at  the  ankle,  again,  perceptibly  later 
than  that  at  the  wrist.  The  arterial  circulation,  accordingly,  is  not 
an  entirely  simple  phenomenon ;  but  is  made  up  of  the  combined 
effects  of  two  different  physical  forces.  In  the  first  place,  there  is 
the  elasticity  of  the  entire  arterial  system,  by  which  the  blood  is 
subjected  to  a  constant  and  uniform  pressure,  quite  independent  of 
the  action  of  the  heart.     Secondly,  there  is  the  alternating  contrac- 


250  THE    CIRCULATION". 

tion  and  relaxation  of  the  heart,  by  which  the  blood  is  driven  in 
rapid  and  successive  impulses  from  the  centre  of  the  circulation,  to 
be  thence  distributed  throughout  the  body. 

The  rapidily  with  which  the  blood  circulates  through  the  arterial 
system  is  very  great.  Its  velocity  is  greatest  in  the  immediate 
neighborhood  of  the  heart,  and  diminishes  somewhat  as  the  blood 
recedes  farther  and  farther  from  the  centre  of  the  circulation.  This 
diminution  in  the  rapidity  of  the  arterial  current  is  due  to  the  suc- 
cessive division  of  the  aorta  and  its  primary  branches  into  smaller 
and  smaller  ramifications,  by  which  the  total  calibre  of  the  arterial 
system,  as  we  have  already  mentioned,  is  somewhat  increased.  The 
blood,  therefore,  flowing  through  a  larger  space  as  it  passes  outward, 
necessarily  goes  more  slowly.  At  the  same  time  the  increased 
extent  of  the  arterial  parietes  with  which  the  blood  comes  in  con- 
tact, as  well  as  the  mechanical  obstacle  arising  from  the  division  of 
the  vessels  and  the  separation  of  the  streams,  undoubtedly  contri- 
bute more  or  less  to  retard  the  currents.  The  mechanical  obstacle, 
however,  arising  from  the  friction  of  the  blood  against  the  walls  of 
the  vessels,  which  would  be  very  serious  in  the  case  of  water  or  any 
similar  fluid  flowing  through  glass  or  metallic  tubes,  has  compara- 
tively little  effect  on  the  rapidity  of  the  arterial  circulation.  This 
can  readily  be  seen  by  microscopic  examination  of  any  transparent 
and  vascular  tissue.  The  internal  surface  of  the  arteries  is  so  smooth 
and  yielding,  and  the  consistency  of  the  circulating  fluid  so  accu- 
rately adapted  to  that  of  the  vessels  which  contain  it,  that  the 
retarding  effects  of  friction  are  reduced  to  a  minimum,  and  the 
blood  in  flowing  through  the  vessels  meets  with  the  least  possible 
resistance. 

It  is  owing  to  this  fact  that  the  arterial  circulation,  though  some- 
what slower  toward  the  periphery  than  near  the  heart,  yet  retains 
a  very  remarkable  velocity  throughout ;  and  even  in  arteries  of  the 
minutest  size  it  is  so  rapid  that  the  shape  of  the  blood-globules  can- 
not be  distinguished  in  it  on  microscopic  examination,  but  only  a 
mingled  current  shooting  forward  with  increased  velocity  at  every 
cardiac  pulsation.  Yolkmann,  in  Germany,  has  determined,  by  a 
very  ingenious  contrivance,  the  velocity  of  the  current  of  blood  in 
some  of  the  large  sized  arteries  in  dogs,  horses,  and  calves.  The 
instrument  which  he  employed  (Fig.  94)  consisted  of  a  metallic 
cylinder  (a),  with  a  perforation  running  from  end  to  end,  and  cor- 
responding in  size  with  the  artery  to  be  examined.  The  artery  was 
then  divided  transversely,  and  its  cardiac  extremity  fastened  to  the 


THE    ARTERIES    AND    THE    ARTERIAL    CIRCULATION.      251 

upper  end  (h)  of  the  instrument,  while  its  peripheral  extremity  was 
fastened  in  the  same  manner  to  the  lower  end  (c).  The  blood 
accordingly  still  kept  on  its  usual  course;  only  passing  for  a  short 
distance  through  the  artificial  tube  (a),  between  the  divided  extremi- 


Fig.  94.  Fig-  95. 


VoLKMANN's  APPARATUS  for  measuring  the  rapidity  of  the  arterial  circulation. 


ties  of  the  artery.  The  instrument,  however,  was  provided,  as  shown 
in  the  accompanying  figures,  with  two  transverse  cylindrical  plugs, 
also  perforated  f  and  arranged  in  such  a  manner,  that  when,  at  u 
given  signal,  the  two  plugs  were  suddenly  turned  in  opposite 
directions,  the  stream  of  blood  would  be  turned  out  of  its  course 
(Fig.  95),  and  made  to  traverse  a  long  bent  tube  of  glass  {d,  d,  d), 
before  again  finding  its  way  back  to  the  lower  portion  of  the  artery. 
In  this  way  the  distance  passed  over  by  the  blood  in  a  given  tii:ie 
could  be  readily  measured  upon  a  scale  attached  to  the  side  of  the 
glass  tube.  Volkmann  found,  as  the  average  result  of  his  obser- 
vations, that  the  blood  moves  in  the  carotid  arteries  of  warm-blooded 
quadrupeds  with  a  velocity  of  12  inches  per  second. 


252  THE    CIRCULATION. 


VENOUS  CIRCULATION. 

The  veins,  which  collect  the  blood  from  the  tissues  and  return  it 
to  the  heart,  are  composed,  like  the  arteries,  of  three  coats ;  an 
inner,  middle,  and  exterior.  In  structure,  they  differ  from  the  arte- 
ries in  containing  a  much  smaller  quantity  of  muscular  and  elastic 
fibres,  and  a  larger  proportion  of  simple  condensed  areolar  tissue. 
They  are  consequently  more  flaccid  and  compressible  than  the 
arteries,  and  less  elastic  and  contractile.  They  are  furthermore 
distinguished,  throughout  the  limbs,  neck,  and  external  portions  of 
the  head  and  trunk,  by  being  provided  with  valves,  consisting  of 
fibrous  sheets  arranged  in  the  form  of  festoons,  and  so  placed  in  the 
cavity  of  the  vein  as  to  allow  the  blood  to  pass  readily  from  the 
periphery  toward  the  heart,  but  to  prevent  altogether  its  reflex  in 
an  opposite  direction. 

The  flow  of  blood  through  the  veins  is  less  powerful  and  regular 
than  that  through  the  arteries.  It  depends  on  the  combined  action 
of  three  different  forces. 

1.  The  force  of  aspiration  of  the  thorax. — When  the  chest  expands, 
by  the  lifting  of  the  ribs  and  the  descent  of  the  diaphragm,  it  has 
the  effect  of  drawing  into  the  thoracic  cavity  all  the  fluids  which 
can  gain  access  to  it.  The  expanded  cavity  is  principally  filled 
by  the  air,  which  passes  in  through  the  trachea  and  fills  the 
bronchial  tubes  and  pulmonary  vesicles.  But  the  blood  in  the 
large  veins  is  also  drawn  into  the  chest  at  the  same  time  and  by 
the  same  force.  It  can  readily  be  seen,  when  the  jugular  and  sub- 
clavian veins  are  exposed  in  the  living  animal,  that  these  vessels 
collapse  with  every  inspiration,  and  fill  out  again  at  the  moment  of 
expiration.  During  inspiration,  the  blood  is  drawn  forward  into 
that  part  of  the  vein  which  occupies  the  cavity  of  the  chest ;  and 
during  expiration,  the  flow  being  momentarily  checked  by  the 
compression  of  the  thorax,  the  vein  fills  up  from  behind,  and  again 
becomes  distended.  This  force  does  not  act  efficiently  at  any  great 
distance  from  the  chest,  owing  to  the  flaccidity  of  the  venous  parietes, 
which  collapse  at  a  short  distance  from  the  entrance  to  the  thoracic 
cavity,  as  the  vein  becomes  emptied  by  inspiration.  It  is  active, 
however,  in  the  neighborhood  of  the  chest,  and  the  respiratory 
movements  exert,  therefore,  a  certain  degree  of  influence  on  the 
venous  circulation. 


VENOUS    CIECULATION 


253 


2.  Tlie  contraction  of  the  voluntary  muscles. — The  veins  which 
convey  the  blood  through  the  limbs,  and  the  parietes  of  the  head 
and  trunk,  lie  among  voluntary  muscles,  which  are  more  or  less 
constantly  in  a  state  of  alternate  contraction  and  relaxation.  At 
every  contraction  these  muscles  become  swollen  laterally,  and,  of 
course,  compress  the  veins  which  are  situated  between  them.  The 
blood,  driven  out  from  the  vein  by  this  pressure,  cannot  regurgitate 
toward  the  capillaries,  owing  to  the  valves,  already  described,  which 
shut  back  and  prevent  its  reflux.  It  is  accordingly  forced  onward 
toward  the  heart;  and  when  the  muscle  relaxes  and  the  vein  is 
liberated  from  pressure,  it  again  fills  up  from  behind,  and  the  cir- 
culation goes  on  as  before.  This  force  is  a  very  efficient  one  in 
producing  the  venous  circulation  ;  since  the  voluntary  muscles  are 
more  or  less  active  in  every  position  of  the  body,  and  the  veins 
constantly  liable  to  be  compressed  by  them.  It  is  on  this  account 
that  the  veins,  in  the  external  parts  of  the  body,  communicate  so 
freely  with  each  other  by  transverse  branches ;  in  order  that  the 
current  of  blood,  which  is  momentarily  excluded  from  one  vein  by 
the  pressure  of  the  muscles,  may  readily  find  a  passage  through 
others,  which  communicate  by  cross  branches  with  the  first.  (Figs. 
96  and  97.) 


Fig.  96. 


Fig.  97. 


Vein  with  valves  open. 


Vein  with  valves  closed;  stream  of 
blood  passing  off  by  a  lateral  channel. 


3.  The  force  of  the  capillary  circulation. — This  last  cause  of  the 
motion  of  the  blood  through  the  veins  is  the  most  important  of  all, 
as  it  is  the  only  one  which  is  constantly  and  universally  active.   In 


254  THE    CIRCULATION. 

fish,  for  example,  respiration  is  performed  altogether  by  gills;  and 
in  reptiles  the  air  is  forced  down  into  the  lungs  by  a  kind  of  deglu- 
tition, instead  of  being  drawn  in  by  the  expansion  of  the  chest.  In 
neither  of  these  classes,  therefore,  can  the  movements  of  respiration 
assist  mechanically  in  the  circulation  of  the  blood.  In  the  splanch- 
nic cavities,  again,  of  all  the  vertebrate  animals,  the  veins  coming 
from  the  internal  organs,  as,  for  example,  the  cerebral,  pulmonary, 
portal,  hepatic,  and  renal  veins,  are  unprovided  with  valves ;  and 
the  passage  of  the  blood  through  them  cannot  therefore  be  effected 
by  any  lateral  pressure.  The  circulation,  however,  constantly  going 
on  in  the  capillaries,  everywhere  tends  to  crowd  the  radicles  of  the 
veins  with  blood ;  and  this  vis  a  tergo,  or  pressure  from  behind,  fills 
the  whole  venous  system  by  a  constant  and  steady  accumulation. 
So  long,  therefore,  as  the  veins  are  relieved  of  blood  at  their  cardiac 
extremity  by  the  regular  pulsations  of  the  heart,  there  is  no  back- 
ward pressure  to  oppose  the  impulse  derived  from  the  capillary  cir- 
culation ;  and  the  movement  of  the  blood  through  the  veins  continues 
in  a  steady  and  uniform  course. 

With  regard  to  the  rapidity  of  the  venous  circulation,  no  direct 
results  have  been  obtained  by  experiment.  Owing  to  the  flaccidity 
of  the  venous  parietes,  and  the  readiness  with  which  the  flow  of 
blood  through  them  is  disturbed,  it  is  not  possible  to  determine  this 
point  for  the  veins,  in  the  same  manner  as  it  has  been  determined 
for  the  arteries.  The  only  calculation  which  has  been  made  in  this 
respect  is  based  upon  a  comparison  of  the  total  capacity  of  the 
arterial  and  venous  systems.  As  the  same  blood  which  passes  out- 
ward through  the  arteries,  passes  inward  again  through  the  veins, 
the  rapidity  of  its  flow  in  each  must  be  in  inverse  proportion  to  the 
capacity  of  the  two  sets  of  vessels.  That  is  to  say,  a  quantity  of 
blood  which  would  pass  in  a  given  time,  with  a  velocity  of  x, 
through  an  opening  equal  to  one  square  inch,  would  pass  during 
the  same  time  through  an  opening  equal  to  two  square  inches,  with 
a  velocity  of  J;  and  would  require,  on  the  other  hand,  a  velocity 
of  2  «,  to  pass  in  the  same  time  through  an  opening  equal  to  one- 
half  a  square  inch.  Now  the  capacity  of  the  entire  venous  system, 
when  distended  by  injection,  is  about  twice  as  great  as  that  of  the 
entire  arterial  system.  During  life,  however,  the  venous  system  is 
at  no  time  so  completely  filled  with  blood  as  is  the  case  with  the 
arteries ;  and  making  allowance  for  this  difference,  we  find  that  the 
entire  quantity  of  venous  blood  is  to  the  entire  quantity  of  arte- 


THE    CAPILLARY    CIKCULATION. 


255 


rial  blood  nearly  as  three  to  two.  The  velocity  of  the  venous 
blood,  as  compared  with  the  arterial,  is  therefore  as  two  to  three ; 
or  about  8  inches  per  second.  It  will  be  understood,  however,  that 
this  calculation  is  altogether  approximative,  and  not  exact ;  since 
the  venous  current  varies,  according  to  many  different  circumstances, 
in  different  parts  of  the  body ;  being  slower  near  the  capillaries, 
and  more  rapid  near  the  heart.  It  expresses,  however,  with  sufl&- 
cient  accuracy,  the  relative  velocity  of  the  arterial  and  venous  cur- 
rents, at  corresponding  parts  of  their  course. 


THE  CAPILLARY  CIRCULATION. 


The  capillary  bloodvessels  are  minute  inosculating  tubes,  which 
permeate  the  vascular  organs  in  every  direction,  and  bring  the 
blood  into  intimate  contact  with  the  substance  of  the  tissues.  They 
are  continuous  with  the  terminal  ramifications  of  the  arteries  on 
the  one  hand,  and  with  the  com- 
mencing rootlets  of  the  veins  on  Fig-  98. 
the  other.  They  vary  somewhat 
in  size  in  different  organs,  and  in 
different  species  of  animals ;  their 
average  diameter  in  the  human 
subject  being  a  little  over  3  (jVw  of 
an  inch.  They  are  composed  of 
a  single,  transparent,  homogene- 
ous, somewhat  elastic,  tubular 
membrane,  which  is  provided  at 
various  intervals  with  flattened, 
oval  nuclei.  As  the  smaller  arte- 
ries approach  the  capillaries,  they 
diminish  constantly  in  size  by 
successive  subdivision,  and  lose 
first  their  external  or  fibrous 
tunic.     They  are  then  composed 

only  of  the  internal  or  homogeneous  coat,  and  the  midde  or  muscu- 
lar. (Fig.  98,  a.)  The  middle  coat  then  diminishes  in  thickness, 
until  it  is  reduced  to  a  single  layer  of  circular,  fusiform,  unstriped, 
muscular  fibres,  which  in  their  turn  disappear  altogether  as  the 
artery  merges  at  last  in  the  capillaries ;  leaving  only,  as  we  have 


SiMALL  AuTERT,  wUh  its  muscular  tiiaic 
(a),  breaking  up  into  capillaries.  From  the  2Jia 
■mater. 


256 


THE    CIECULATIOX. 


already  mentioned,  a  simple,  homogeneous,  nucleated,  tubular  mem- 
brane, which  is  continuous  with  the  internal  arterial  tunic. 

The  capillaries  are  further  distinguished  from  both  arteries  and 
veins  by  their  frequent  inosculation.  The  arteries  constantly 
divide  and  subdivide,  as  they  pass  from  within  outward;  while 
the  veins  as  constantly  unite  with  each  other  to  form  larger  and 
less  numerous  branches  and  trunks,  as  they  pass  from  the  circum- 
ference toward  the  centre.  But  the  capillaries  simply  inosculate 
with  each  other  in  every  direction,  in  such  a  manner  as  to  form  an 
interlacing  network  or  plexus,  the  capillary  plexus  (Fig.  99),  which 
is  exceedingly  rich  and  abundant  in  some  organs,  less  so  in  others. 
The  spaces  included  between  the  meshes  of  the  capillary  network 
vary  also,  in  shape  as  well  as  in  size,  in  different  parts  of  the  body. 

In  the  muscular  tissue  they 
'^'  form  long  parallelograms  ;  in 

the  areolar  tissue,  irregular 
shapeless  figures,  correspond- 
ing with  the  direction  of  the 
fibrous  bundles  of  which  the 
tissue  is  composed.  In  the 
mucous  membrane  of  the 
large  intestine,  the  capillaries 
include  hexagonal  or  nearly 
circular  spaces,  inclosing  the 
orifices  of  the  follicles.  In 
the  papillae  of  the  tongue  and 
of  the  skin,  and  in  the  tufts 
of  the  placenta,  they  are 
arranged  in  long  spiral  loops, 
and  in  the  adipose  tissue  in  wide  meshes,  among  which  the  fat 
vesicles  are  entangled. 

The  motion  of  the  hlood  in  the  cajnllaries  may  be  studied  by 
examining  under  the  microscope  any  transparent  tissue,  of  a 
sufficient  degree  of  vascularity.  One  of  the  most  convenient  parts 
for  this  purpose  is  the  web  of  the  frog's  foot.  "When  properly 
prepared  and  kept  moistened  by  the  occasional  addition  of  water 
to  the  integument,  the  circulation  will  go  on  in  its  vessels  for  an 
indefinite  length  of  time.  The  blood  can  be  seen  entering  the 
field  by  the  smaller  arteries,  shooting  along  through  them  with 
great  rapidity  and  in  successive  impulses^  and  flowing  off  again  by 
the  veins  at  a  somewhat  slower  rate.     In  the  capillaries  themselves 


Capillary  Network  from  tveb  of  frog's  foot. 


THE    CAPILLARY    CIRCULATION. 


257 


Capillary  Circulation  in  web  of  frog's  foot. 


the  circulation  is  considerably  less  rapid  than  in  either  the  arteries 
or  the  veins.  It  is  also  perfectly  steady  and  uninterrupted  in  its 
flow.  The  blood  passes  along  in  a  uniform  and  continuous  current, 
without  any  apparent  contraction  or  dilatation  of  the  vessels,  very 
much  as  if  it  were  flowing 

through   glass  tubes.     An-  ^^s-  ^^^• 

other  very  remarkable  pe- 
culiarity of  the  capillary 
circulation  is  that  it  has  no 
definite  direction.  The  nu- 
merous streams  of  which  it 
is  composed  (Fig.  100)  do 
not  tend  to  the  right  or  to 
the  left,  nor  toward  any  one 
particular  point.  On  the 
contrary,  they  pass  above 
and  below  each  other,  at 
right  angles  to  each  other's 
course,  or  even  in  opposite 
directions;  so  that  the  blood, 
while  in  the  capillaries,  merely  circulates  promiscuously  among 
the  tissues,  in  such  a  manner  as  to  come  intimately  in  contact  with 
every  part  of  their  substance. 

The  motion  of  the  white  and  red  globules  in  the  circulating  blood 
is  also  peculiar,  and  shows  very  distinctly  the  difference  in  their 
consistency  and  other  physical  properties.  In  the  larger  vessels 
the  red  globules  are  carried  along  in  a  dense  column,  in  the  central 
part  of  the  stream ;  while  near  the  edges  of  the  vessel  there  is  a 
transparent  space  occupied  only  by  the  clear  plasma  of  the  blood, 
in  which  no  red  globules  are  to  be  seen.  In  the  smaller  vessels, 
the  globules  pass  along  in  a  narrower  column,  two  by  two,  or 
following  each  other  in  single  file.  The  flexibility  and  semi-fluid 
consistency  of  these  globules  are  here  very  apparent,  from  the 
readiness  with  which  they  become  folded  up,  bent  or  twisted  in 
turning  corners,  and  the  ease  with  which  they  glide  through  minute 
branches  of  communication,  smaller  in  diameter  than  themselves. 
The  white  globules,  on  the  other  hand,  flow  more  slowly  and  with 
greater  difficulty  through  the  vessels.  They  drag  along  the  exter- 
nal portions  of  the  current,  and  are  sometimes  momentarily  arrested; 
apparently  adhering  for  a  few  seconds  to  the  internal  surface  of  the 
vessel.  Whenever  the  current  is  obstructed  or  retarded  in  any 
17 


258  THE    CIRCULATION. 

manner,  the  white  globules  accumulate  in  the  affected  portion,  and 
become  more  numerous  there  in  proportion  to  the  red. 

It  is  during  the  capillary  circulation  that  the  blood  serves  for 
the  nutrition  of  the  vascular  organs.  Its  fluid  portions  slowly 
transude  through  the  walls  of  the  vessels,  and  are  absorbed  by  the 
tissues  in  such  proportion  as  is  requisite  for  their  nourishment. 
The  saline  substances  enter  at  once  into  the  composition  of  the 
surrounding  parts,  generally  without  undergoing  any  change.  The 
phosphate  of  lime,  for  example,  is  taken  up  in  large  quantity  by 
the  bones  and  cartilages,  and  in  smaller  quantity  by  the  softer  parts; 
while  the  chlorides  of  sodium  and  potassium,  the  carbonates,  sul- 
phates, &c.,  are  appropriated  in  special  proportions  by  the  different 
tissues,  according  to  the  quantity  necessary  for  their  organization. 
The  albuminous  ingredients  of  the  blood,  on  the  other  hand,  are 
not  only  absorbed  in  a  similar  manner  by  the  animal  tissues,  but  at 
the  same  time  are  transformed  by  catalysis,  and  converted  into  new 
materials,  characteristic  of  tbe  different  tissues.  In  this  way  are 
produced  the  musculine  of  the  muscles,  the  osteine  of  the  bones,  the 
cartilagine  of  the  cartilages,  &c.  &c.  It  is  probable  that  this  trans- 
formation does  not  take  place  in  the  interior  of  the  vessels  them- 
selves ;  but  that  the  organic  ingredients  of  the  blood  are  absorbed 
by  the  tissues,  and  at  the  same  moment  converted  into  new  mate- 
rials, by  contact  with  their  substance.  The  blood  in  this  way  fur- 
nishes, directly  or  indirectly,  all  the  materials  necessary  for  the 
nutrition  of  the  body. 

The  physical  forces  which  produce  the  movement  of  the  blood 
through  the  capillary  vessels  are  different  from  those  which  operate 
in  producing  the  venous  and  arterial  circulations.  The  force  of  the 
heart's  action,  whicb  drives  the  blood  througb  the  arteries,  merely 
secures  a  constant  supply  of  blood  to  the  commencement  of  the 
capillaries,  but  is  not  of  itself  the  cause  of  the  continued  current 
through  the  latter  vessels.  This  is  shown  by  the  fact  that  a  capil- 
lary circulation  exists  in  vegetables,  where  there  is  no  central  con- 
tractile organ,  and  where  the  circulation  of  the  sap  must  necessarily 
depend  on  other  forces.  In  fish,  again,  the  heart  is  separated  from 
the  general  circulation  by  the  capillary  system  of  the  gills,  which 
intervenes  between  them,  and  by  which  the  impulsive  force  of  the 
cardiac  contractions  must  be,  to  say  the  least,  very  much  diminished. 
In  the  quadrupeds,  also,  and  in  the  human  subject,  the  bepatic 
capillary  circulation  goes  on  with  the  same  regularity  as  elsewhere, 
notwithstanding  that  it  is  supplied  by  the  portal  vein  with  blood 


THE    CAPILLARY    CIRCULATION.  259 

which  has  already  passed  through  the  capillaries  of  the  digestive 
apparatus  before  reaching  those  of  the  liver.  Furthermore,  it  is  evi- 
dent, from  the  commonest  observation,  that  the  capillary  circulation, 
in  various  parts  of  the  body,  is  liable  to  be  increased  or  diminished 
in  activity  from  causes  of  a  purely  local  character,  and  entirely  inde- 
pendent of  the  action  of  the  heart.  The  countenance  may  become 
flushed  or  pale,  and  temporary  congestions  may  take  place  in  any 
of  the  internal  organs,  as,  for  example,  in  the  stomach  and  intestine 
during  the  digestive  process  ;  so  that  a  much  larger  quantity  of 
blood  may  circulate  through  them  in  a  given  time,  though  the 
force  of  the  heart's  action  remains  constant. 

The  study  of  the  microscopic  appearances  of  inflammation  in 
transparent  tissues,  so  well  observed  by  Lebert^  and  others,  leads  to 
a  similar  result.  At  the  time  when  the  inflammatory  process  begins 
to  be  established,  the  circulation  is  seen  to  be  retarded.  The  blood 
moves  more  slowly  through  the  capillaries,  and  its  current  becomes 
more  and  more  sluggish  as  the  morbid  action  proceeds.  The  blood- 
globules  become  impacted  in  the  vessels,  and  finally,  at  those  points 
where  the  inflammation  is  most  active,  the  circulation  stops  alto- 
gether, and  a  local  stasis  of  the  blood  is  produced.  This,  however, 
is  not  owing  to  any  simple  mechanical  obstacle  to  its  passage,  since 
the  vessels,  during  the  entire  period  of  the  inflammatory  congestion, 
are  actually  dilated  by  the  blood  which  accumulates  in  them ;  nor, 
on  the  other  hand,  is  it  owing  to  a  diminution  in  the  force  of  the 
heart's  action,  since  the  cardiac  pulsations  are  still  as  powerful  as 
ever,  and  in  the  healthy  tissues,  in  the  immediate  neighborhood  of 
the  inflamed  parts,  the  circulation  may  be  seen  going  on  at  the 
same  time  in  its  ordinary  manner. 

All  these  facts  show  beyond  a  doubt  that  the  force  which  regu- 
lates and  controls  the  capillary  circulation  is  a  local  one,  and  resident 
evidently  in  the  capillaries  and  tissues  of  the  part  itself.  This  force 
not  only  carries  the  blood  through  the  capillaries,  but  delivers  it 
also  into  the  veins ;  and  by  supplying  the  requisite  vis  a  iergo^  con- 
stitutes, as  we  have  already  mentioned,  one  of  the  most  eflBeient 
causes  of  the  venous  circulation.  It  is  not  only  independent  to  a 
certain  extent,  during  life,  of  the  heart's  action,  but  will  even  con- 
tinue for  a  time  after  the  heart  has  stopped;  so  that  at  the  moment 
of  death,  when  the  cardiac  pulsations  cease,  the  capillaries  empty 
themselves  of  blood,  which  accumulates  in  the  large  trunks  and 

'  Pliysiologie  Pathol ogique,  Paris,  1845,  voL  i.  p.  2. 


260  THE    CIRCULATION. 

branches  of  the  veins.  Precisely  what  is  the  nature  of  this  force, 
thus  active  in  producing  the  capillary  circulation,  it  is  not  easy  to 
determine.  In  all  probability  it  results,  in  great  measure,  from  the 
actions  of  endosmosis  and  exosmosis,  which  are  constantly  going  on 
between  the  blood  contained  in  the  capillaries,  and  the  tissues  situated 
outside  of  them  ;  and  which,  varying  in  intensity  in  different  organs, 
and  even  in  the  same  organ  at  different  times,  produce  those  local 
variations  in  the  activity  of  the  capillary  circulation  which  con- 
stantly present  themselves  to  the  observation  of  the  physiologist. 

The  rapidity  of  the  circulation  in  the  capillary  vessels  is  much 
less  than  in  the  arteries  or  the  veins.  It  may  be  measured,  with 
a  tolerable  approach  to  accuracy,  during  the  microscopic  examina- 
tion of  transparent  and  vascular  tissues,  as,  for  example,  the  web  of 
the  frog's  foot,  or  the  mesentery  of  the  rat.  The  results  obtained 
in  this  way  by  different  observers  (Valentine,  Weber,  Volkmann, 
&c.)  show  that  the  rate  of  movement  of  the  blood  through  the 
capillaries  is  rather  less  than  one-thirtieth  of  an  inch  per  second ; 
or  not  quite  two  inches  per  minute.  Since  the  rapidity  of  the 
current,  as  we  have  mentioned  above,  must  be  in  inverse  ratio  to 
the  entire  calibre  of  the  vessels  through  which  it  moves,  it  follows 
that  the  united  calibre  of  all  the  capillaries  of  the  body  must  be 
from  350  to  400  times  greater  than  that  of  the  arteries.  It  must 
not  be  supposed  from  this,  however,  that  the  whole  quantity  of  blood 
contained  in  the  capillaries  at  any  one  time  is  so  much  greater  than 
that  in  the  arteries ;  since,  although  the  united  calibre  of  the  capil- 
laries is  very  large,  their  length  is  very  small.  The  effect  of  the 
anatomical  structure  of  the  capillary  system  is,  therefore,  merely  to 
disseminate  a  comparatively  small  quantity  of  blood  over  a  very 
large  space,  so  that  the  chemico-physiological  reactions,  necessary 
to  nutrition,  may  take  place  with  promptitude  and  energy.  For 
the  same  reason,  although  the  rate  of  movement  of  the  blood  in 
these  vessels  is  very  slow,  yet  as  the  distance  to  be  passed  over 
between  the  arteries  and  veins  is  very  small,  the  blood  really  re- 
quires but  a  short  time  to  traverse  the  capillary  system,  and  to 
commence  its  returning  passage  by  the  veins. 


GENERAL  CONSIDERATIONS. 

The  rapidity  with  which  the  blood  passes  through  the  entire  round 
of  the  circulation  is  a  point  of  great  interest,  and  one  which  has 


KAPIDITY    OF    THE    CIRCULATION.  261 

received  a  considerable  share  of  attention.  The  results  of  such 
experiments,  as  have  been  tried,  show  that  this  rapidity  is  much 
greater  than  would  have  been  anticipated.  Hering,  Poisseuille,  and 
Matteucci,*  have  all  experimented  on  this  subject  in  the  following 
manner.  A  solution  of  ferrocyanide  of  potassium  was  injected 
into  the  right  jugular  vein  of  a  horse,  at  the  same  time  that  a  liga- 
ture was  placed  upon  the  corresponding  vein  on  the  left  side,  and 
an  opening  made  in  it  above  the  ligature.  The  blood  flowing  from 
the  left  jugular  vein  was  then  received  in  separate  vessels,  which 
were  changed  every  five  seconds,  and  the  contents  afterward  exa- 
mined. It  was  thus  found  that  the  blood  drawn  from  the  first  to 
the  twentieth  second  contained  no  traces  of  the  ferrocyanide ;  but 
that  which  escaped  from  the  vein  at  the  end  of  from  twenty  to 
twenty-five  seconds,  showed  unmistakable  evidence  of  the  presence 
of  the  foreign  salt.  The  ferrocyanide  of  potassium  must  therefore, 
during  this  time,  have  passed  from  the  point  of  injection  to  the 
right  side  of  the  heart,  thence  to  the  lungs  and  through  the  pulmo- 
nary circulation,  returned  to  the  heart,  passed  out  again  through 
the  arteries  to  the  capillary  system  of  the  head  and  neck,  and 
thence  have  commenced  its  returning  passage  to  the  right  side  of 
the  heart,  through  the  jugular  vein. 

If  this  experiment  were  altogether  decisive,  it  would  demonstrate 
that  the  blood  performs  the  entire  round  of  the  circulation  in  from 
20  to  25  seconds.  But  it  is  not  so  conclusive  in  this  respect  as  might 
at  first  be  supposed.  In  reality,  it  only  shows  that  the  solution  of  the 
ferrocyanide  passes  round  to  the  opposite  vein  during  this  period,  but 
it  does  not  necessarily  follow  that  the  entire  blood  moves  with  the 
same  rapidity ;  since  the  injected  saline  solution  may  diffuse  itself 
through  the  blood,  so  as  to  travel  faster  than  the  blood  itself.  Sub- 
sequent experiments  of  Poisseuille  showed,  in  fact,  that  other  sub- 
stances injected  at  the  same  time  may  either  accelerate  or  retard  the 
movement  of  the  ferrocyanide.  If  a  little  nitrate  of  potass,  for 
example,  were  injected  together  with  the  ferrocyanide,  the  latter 
salt  appeared  in  the  blood  flowing  from  the  opposite  jugular  at  the 
end  of  twenty  seconds.  A  solution  of  acetate  of  ammonia,  again, 
shortened  the  period  to  eighteen  seconds.  On  the  other  hand,  a 
little  alcohol,  injected  at  the  same  time,  retarded  its  motion  to  such 
a  degree,  that  the  ferrocyanide  could  not  be  detected  till  the  end  of 

'  Physical  Phenomena  of  Living  Beings,  Pereira's  translation,  Philada.  ed  ,  1848, 
p.  317. 


262  THE    CIECULATION. 

forty  to  forty-five  seconds.  These  facts  show  conclusively  that  the 
time  required  for  a  solution  of  ferrocyanide  of  potassium  to  appear 
in  the  opposite  jugular  vein  does  not  depend  altogether  on  the  rate 
of  movement  of  the  blood  itself,  but  is  influenced  very  considerably 
by  the  chemical  constitution  and  physical  properties  of  the  injected 
fluid,  and  its  physical  relations  to  the  blood  and  to  the  walls  of  the 
bloodvessels.  Furthermore,  we  have  already  seen  that  the  different 
ingredients  of  the  blood  do  not  all  circulate  with  the  same  rapidity. 
In  a  microscopic  examination,  for  example,  it  is  evident  that  the 
white  globules  of  the  blood  move  much  more  slowly  than  the  red; 
and  it  is  very  possible  that  the  red  globules  themselves  pass  less 
rapidly  from  one  point  to  another  than  those  portions  of  the  blood 
which  are  entirely  fluid. 

The  truth  is,  however,  that  we  cannot  fix  upon  any  uniform  rate 
which  shall  express  exactly  the  time  required  by  the  entire  blood 
to  pass  the  round  of  the  whole  vascular  system,  and  return  to  a 
given  point.  The  circulation  of  the  blood,  far  from  being  a  simple 
phenomenon,  like  a  current  of  water  through  a  circular  tube,  is, 
on  the  contrary,  extremely  complicated  in  all  its  anatomical  and 
physiological  conditions;  and  it  differs  in  rapidity,  as  well  as  in  its 
physical  and  chemical  phenomena,  in  different  parts  of  the  circu- 
latory apparatus.  We  have  already  seen  how  much  the  form  of 
the  capillary  plexus  varies  in  different  organs.  In  some  the  vascu- 
lar network  is  close,  in  others  comparatively  open.  In  some  its 
meshes  are  circular  in  shape,  in  others  polygonal,  in  others  rectan- 
gular. In  some  the  vessels  are  arranged  in  twisted  loops,  in  others 
they  communicate  by  irregular  but  abundant  inosculations.  The 
mere  distance  at  which  an  organ  is  situated  from  the  heart  must 
modify  to  some  extent  the  time  required  for  its  blood  to  return 
again  to  the  centre  of  the  circulation.  The  blood  which  passes 
through  the  coronary  arteries,  for  example,  and  the  capillaries  of 
the  heart  itself,  must  be  returned  to  the  right  auricle  in  a  compara- 
tively short  time  ;  while  that  which  is  carried  by  the  carotids  into 
the  capillary  system  of  the  head  and  neck,  to  return  by  the  jugulars, 
will  require  a  longer  interval.  That,  again,  which  descends  by  the 
abdominal  aorta  and  its  divisions,  to  the  lower  extremities,  and 
which,  after  circulating  through  the  tissues  of  the  leg  and  foot, 
mounts  upward  through  the  whole  course  of  the  saphena,  femoral, 
iliac  and  abdominal  veins,  must  be  still,  longer  on  its  way  ;  while 
that  which  circulates  through  the  abdominal  digestive  organs  and 
is  then  collected  by  the  portal  system,  to  be  again  dispersed  through 


LOCAL    VARIATIONS.  263 

the  glandular  tissue  of  the  liver,  requires  undoubtedly  a  longer 
period  still  to  perform  its  double  capillary  circulation.  The  blood, 
therefore,  arrives  at  the  right  side  of  the  heart,  from  different  parts 
of  the  body,  at  successive  intervals;  and  may  pass  several  times 
through  one  organ  while  performing  a  single  circulation  through 
another. 

Furthermore,  the  chemical  phenomena  taking  place  in  the  blood 
and  the  tissues  vary  to  a  similar  extent  in  different  organs.  The 
actions  of  transformation  and  decomposition,  of  nutrition  and  secre- 
tion, of  endosmosis  and  exosmosis,  which  go  on  simultaneously 
throughout  the  body,  are  yet  extremely  varied  in  their  character, 
and  produced  a  similar  variation  in  the  phenomena  of  the  circula- 
tion. In  one  organ  the  blood  loses  more  fluid  than  it  absorbs ;  in 
another  it  absorbs  more  than  it  loses.  The  venous  blood,  conse- 
quently, has  a  different  composition  as  it  returns  from  different 
organs.  In  the  brain  and  spinal  cord  it  gives  up  those  ingredients 
necessary  for  the  nutrition  of  the  nervous  matter,  and  absorbs  cho- 
lesterine  and  other  materials  resulting  from  its  waste;  in  the  muscles 
it  loses  those  substances  necessary  for  the  supply  of  the  muscular 
tissue,  and  in  the  bones  those  which  are  requisite  for  the  osseous 
system.  In  the  parotid  gland  it  yields  the  ingredients  of  the  saliva; 
in  the  kidneys,  those  of  the  urine.  In  the  intestine  it  absorbs  in 
large  quantity  the  nutritious  elements  of  the  digested  food ;  and  in 
the  liver,  gives  up  substances  destined  finally  to  produce  the  bile, 
at  the  same  time  that  it  absorbs  sugar,  which  has  been  produced 
in  the  hepatic  tissue.  In  the  lungs,  again,  it  is  the  elimination  of 
carbonic  acid  and  the  absorption  of  oxygen  that  constitute  its  prin- 
cipal changes.  It  has  been  already  remarked  that  the  temperature 
of  the  blood  varies  in  different  veins,  according  to  the  peculiar 
chemical  and  nutritive  changes  going  on  in  the  organs  from  which 
they  originate.  Its  color,  even,  which  is  also  dependent  on  the 
chemical  and  nutritive  actions  taking  place  in  the  capillaries,  varies 
in  a  similar  manner.  In  the  lungs,  it  changes  from  blue  to  red ; 
in  the  capillaries  of  the  general  system,  from  red  to  blue.  But  its 
tinge  also  varies  very  considerably  in  different  parts  of  the  general 
circulation.  The  blood  of  the  hepatic  veins  is  darker  than  that  of 
the  femoral  or  brachial  vein.  In  the  renal  veins  it  is  very  much 
brighter  than  in  the  vena  cava;  and  when  the  circulation  through 
the  kidneys  is  free,  the  blood  returning  from  them  is  nearly  as  red 
as  arterial  blood. 

We  must  regard  the  circulation  of  the  blood,  therefore,  not  as  a 


264 


THE    CIRCULATION. 


simple  process,  but  as  made  up  of  many  different  circulations,  going 
on  simultaneously  in  different  organs.     It  has  been  customary  to 

illustrate  it,  in  diagram,  by  a  double 
circle,  or  figure  of  8,  of  which  the 
upper  arc  is  used  to  represent  the 
pulmonary,  the  lower  the  general  cir- 
culation. This,  however,  gives  but  a 
very  imperfect  idea  of  the  entire  cir- 
culation, as  it  really  takes  place.  It 
would  be  much  more  accurately  re- 
presented by  such  a  diagram  as  that 
given  in  Fig.  101,  in  which  its  varia- 
tions in  different  parts  of  the  body  are 
indicated  in  such  a  manner  as  to  show, 
in  some  degree,  the  complicated  cha- 
racter of  its  phenomena.  The  circula- 
tion is  modified  in  these  different  parts, 
not  only  in  its  mechanism,  but  also  in 
its  rapidity  and  quantity,  and  in  the 
nutritive  functions  performed  by  the 
blood.  In  one  part,  it  stimulates  the 
nervous  centres  and  the  organs  of 
special  sense;  in  others  it  supplies  the 
fluid  secretions,  or  the  ingredients  of 
the  solid  tissues.  One  portion,  in 
passing  through  the  digestive  appara- 
tus, absorbs  the  materials  requisite 
for  the  nourishment  of  the  body ;  an- 
other, in  circulating  through  the  lungs, 
exhales  the  carbonic  acid  which  it  has 
accumulated  elsewhere,  and  absorbs 
the  oxygen  which  is  afterward  trans- 
ported to  distant  tissues  by  the  current 
of  arterial  blood.  The  phenomena  of 
the  circulation  are  even  liable,  as  we 
have  already  seen,  to  periodical  va- 
riations in  the  same  organ;  increas- 
ing or  diminishing  in  intensity  with 
the  condition  of  rest  or  activity  of 
the  whole  body,  or  of  the  particular 
organ  which  is  the  subject  of  observation. 


Diagram  of  the  Circulation. — 1. 
Heart.  2.  Lungs.  3.  Head  and  upper 
extremities.  4.  Spleen.  5.  Intestine.  6. 
Kidney.    7.  Lower  extremities.  8   Liver. 


SECRETION.  265 


CHAPTER   XV. 

SECRETION. 

We  have  already  seen,  in  the  last  chapter,  how  the  elements  of 
the  blood  are  absorbed  by  the  tissues  during  the  capillary  circula- 
tion, and  assimilated  by  them  or  converted  into  their  own  substance. 
In  this  process,  the  inorganic  or  saline  matters  are  mostly  taken  up 
unchanged,  and  are  merely  appropriated  by  the  surrounding  parts  in 
particular  quantities ;  while  the  organic  substances  are  transformed 
into  new  compounds,  characteristic  of  the  dififerent  tissues  by  which 
they  are  assimilated.  In  this  way  the  various  tissues  of  the  body, 
though  they  have  a  diiferent  chemical  composition  from  the  blood, 
are  nevertheless  supplied  by  it  with  appropriate  ingredients,  and 
their  nutrition  constantly  maintained. 

Beside  this  process,  which  is  known  by  the  name  of  "  assimila- 
tion," there  is  another  somewhat  similar  to  it,  which  takes  place  in 
the  different  glandular  organs,  known  as  the  process  of  secretion.  It 
is  the  object  of  this  function  to  supply  certain  fluids,  differing  in 
chemical  constitution  from  the  blood,  which  are  required  to  assist 
in  various  physical  and  chemical  actions  going  on  in  the  body. 
These  secreted  fluids,  or  "secretions,"  as  they  are  called,  vary  in 
consistency,  density,  color,  quantity,  and  reaction.  Some  of  them 
are  thin  and  watery,  like  the  tears  and  the  perspiration ;  others  are 
viscid  and  glutinous,  like  mucus  and  the  pancreatic  fluid.  They 
are  alkaline  like  the  saliva,  acid  like  the  gastric  juice,  or  neutral 
like  the  bile.  Each  secretion  contains  water  and  the  inorganic  salts 
of  the  blood,  in  varying  proportions;  and  is  furthermore  distin- 
guished by  the  presence  of  some  peculiar  animal  substance  which 
does  not  exist  in  the  blood,  but  which  is  produced  by  the  secreting 
action  of  the  glandular  organ.  As  the  blood  circulates  through  the 
capillaries  of  the  gland,  its  watery  and  saline  constituents  transude 
in  certain  quantities,  and  are  discharged  into  the  excretory  duct. 
At  the  same  time,  the  glandular  cells,  which  have  themselves  been 
nourished  by  the  blood,  produce  a  new  substance  by  the  catalytic 


266  SECRETION. 

transformation  of  their  organic  constituents;  and  this  new  substance 
is  discharged  also  into  the  excretory  duct  and  mingled  with  the 
other  ingredients  of  the  secreted  fluid.  A  true  secretion,  therefore, 
is  produced  only  in  its  own  particular  gland,  and  cannot  be  formed 
elsewhere,  since  the  glandular  cells  of  that  organ  are  the  only 
ones  capable  of  producing  its  most  characteristic  ingredient.  Thus 
pepsine  is  formed  only  in  the  tubules  of  the  gastric  mucous  mem- 
brane, pancreatine  only  in  the  pancreas,  tauro-cholate  of  soda  only 
in  the  liver. 

One  secreting  gland,  consequently,  can  never  perform  vicariously 
the  office  of  another.  Those  instances  which  have  been  from  time 
to  time  reported  of  such  an  unnatural  action  are  not,  properly 
speaking,  instances  of  "vicarious  secretion;"  but  only  cases  in 
which  certain  substances,  already  existing  in  the  blood,  have  made 
their  appearance  in  secretions  to  which  they  do  not  naturally  belong. 
Thus  cholesterine,  which  is  produced  in  the  brain  and  is  taken  up 
from  it  by  the  blood,  usually  passes  out  with  the  bile ;  but  it  may 
also  appear  in  the  fluid  of  hydrocele,  or  in  inflammatory  exuda- 
tions. The  sugar,  again,  which  is  produced  in  the  liver  and  taken 
up  by  the  blood,  when  it  accumulates  in  large  quantity  in  the  cir- 
culating fluid,  may  pass  out  with  the  urine.  The  coloring  matter 
of  the  bile,  in  cases  of  biliary  obstruction,  may  be  reabsorbed,  and 
so  make  its  appearance  in  the  serous  fluids,  or  even  in  the  perspira- 
tion. In  these  instances,  however,  the  unnatural  ingredient  is  not 
actually  produced  by  the  kidneys,  or  the  perspiratory  glands,  but 
is  merely  supplied  to  them,  already  formed,  by  the  blood.  Cases 
of  *'  vicarious  menstruation"  are  simply  capillary  hemorrhages 
which  take  place  from  various  mucous  membranes,  owing  to  the 
general  disturbance  of  the  circulation  in  amenorrhcea.  A  true 
secretion,  however,  is  always  confined  to  the  gland  in  which  it 
naturally  originates. 

The  force  by  which  the  different  secreted  fluids  are.  prepared  in 
the  glandular  organs,  and  discharged  into  their  ducts,  is  a  peculiar 
one,  and  resident  only  in  the  glands  themselves.  It  is  not  simply 
a  process  of  filtration,  in  which  the  ingredients  of  the  secretion 
exude  from  the  bloodvessels  by  exosmosis  under  the  influence  of 
pressure ;  since  the  most  characteristic  of  these  ingredients,  as  we 
have  already  mentioned,  do  not  pre-exist  in  the  blood,  but  are 
formed  in  the  substance  of  the  gland  itself.  Substances,  even, 
which  already  exist  in  the  blood  in  a  soluble  form,  may  not  have 
the  power  of  passing  out  through  the  glandular  tissue.    Bernard 


SECRETION.  267 

has  found'  that  ferrocjanide  of  potassium,  when  injected  into  the 
jugular  vein,  though  it  appears  with  great  facility  in  the  urine, 
does  not  pass  out  with  the  saliva;  and  even  that  a  solution  of 
the  same  salt,  injected  into  the  duct  of  the  parotid  gland,  is  ab- 
sorbed, taken  up  by  the  blood,  and  discharged  with  the  urine ;  but 
does  not  appear  in  the  saliva,  even  of  the  gland  into  which  it  has 
been  injected.  The  force  with  which  the  secreted  fluids  accumulate 
in  the  salivary  ducts  has  also  been  shown  by  Ludwig's  experi- 
ments'* to  be  sometimes  greater  than  the  pressure  in  the  bloodves- 
sels. This  author  found,  by  applying  mercurial  gauges  at  the  same 
time  to  the  duct  of  Steno  and  to  the  artery  of  the  parotid  gland,  that 
the  pressure  in  the  duct  from  the  secreted  saliva  was  considerably 
greater  than  that  in  the  artery  from  the  circulating  blood ;  so  that 
the  passage  of  the  secreted  fluids  had  really  taken  place  in  a  direc- 
tion contrary  to  that  which  would  have  been  caused  by  the  simple 
influence  of  pressure. 

The  process  of  secretion,  therefore,  is  one  which  depends  upon 
the  peculiar  anatomical  and  chemical  constitution  of  the  glandular 
tissue  and  its  secreting  cells.  These  cells  have  the  property  of 
absorbing  and  transmitting  from  the  blood  certain  inorganic  and 
saline  substances,  and  of  producing,  by  chemical  metamorphosis, 
certain  peculiar  animal  matters  from  their  own  tissue.  These  sub- 
stances are  then  mingled  together,  dissolved  in  the  watery  fluids 
of  the  secretion,  arud  discharged  simultaneously  by  the  excretory 
duct. 

All  the  secreting  organs  vary  in  activity  at  different  periods. 
Sometimes  they  are  nearly  at  rest ;  while  at  certain  periods  they 
become  excited,  under  the  influence  of  an  occasional  or  periodical 
stimulus,  and  then  pour  out  their  secretion  with  great  rapidity  and  in 
large  quantity.  The  perspiration,  for  example,  is  usually  so  slowly 
secreted  that  it  evaporates  as  rapidly  as  it  is  poured  out,  and  the 
surface  of  the, skin  remains  dry;  but  under  the  influence  of  unusual 
bodily  exercise  or  mental  excitement  it  is  secreted  much  faster 
than  it  can  evaporate,  and  the  whole  integument  becomes  covered 
with  moisture.  The  gastric  juice,  again,  in  the  intervals  of  digestion 
is  either  not  secreted  at  all,  or  is  produced  in  a  nearly  inappreciable 
quantity ;  but  on  the  introduction  of  food  into  the  stomach,  it  is 
immediately  poured  out  in  such  abundance,  that  between  two  and 
three  ounces  may  be  collected  in  a  quarter  of  an  hour. 

'  Lecjons  de  Physiologie  ExiJerimentale.     Paris,  1856,  tome  ii.  p.  96,  et  seq. 
2  Ibid  ,  p.  106. 


268  SECRETION. 

« 

The  principal  secretions  met  with  in  the  animal  body  are  as 
follows : — 

1.  Mucus.  6.  Saliva. 

2.  Sebaceous  matter.  7.  Gastric  juice. 

3.  Perspiration.  8.  Pancreatic  juice. 

4.  The  tears.  9.  Intestinal  juice. 

5.  The  milk.  10.  Bile. 

The  last  five  of  these  fluids  have  already  been  described  in  the 
preceding  chapters.  We  shall  therefore  only  require  to  examine 
at  present  the  five  following,  viz.,  mucus,  sebaceous  matter,  per- 
spiration, the  tears,  and  the  milk,  together  with  some  peculiarities 
in  the  secretion  of  the  bile. 

1.  Mucus. — Nearly  all  the  mucous  membranes  are  provided  with 
follicles  or  glandulas,  in  which  the  mucus  is  prepared.  These  folli- 
cles are  most  abundant  in  the  lining  membrane  of  the  mouth,  nares, 
pharynx,  oesophagus,  trachea  and  bronchi,  vagina,  and  male  urethra. 
They  are  generally  of  a  compound  form,  consisting  of  a  number  of 
secreting  sacs  or  cavities,  terminating  at  one  end  in  a  blind  ex- 
tremity, and  opening  by  the  other  into  a  common  diict  by  which 
the  secreted  fluid  is  discharged.  Each  ultimate  secreting  sac  or 
follicle  is  lined  with  glandular  epithelium  (Fig.  102),  and  surround- 
ed on  its  external  surface  by  a  network  of  capillary  bloodvessels. 
These  vessels,  penetrating  deeply  into  the 
interstices  between  the  follicles,  bring  the 
blood  nearly  into  contact  with  the  epithelial 
cells  lining  its  cavity.  It  is  these  cells 
which  prepare  the  secretion,  and  discharge 
it  afterward  into  the  commencement  of  the 
„         excretory  duct. 

Follicles      of     a     Com-  J 

POUND  Mucous  Glandule.        The   mucus,  produccd    in    the   manner 

From  the  human  subject.     (After  .,  -i  .,       ■,     .  ,  ,,  n     •  ^ 

K;3iiiker.)_a.  Membrane  of  the .  ^bovc  dcscribcd,  IS  a  clcar,  colorlcss  fluid, 
follicle,  h,  c.  Epithelium  of  the  which  is  pourcd  out  in  larger  or  smaller 
quantity  on  the  surface  of  the  mucous 
membranes.  It  is  distinguished  from  other  secretions  by  its  vis- 
cidity, which  is  its  most  marked  physical  property,  and  which 
depends  on  the  presence  of  a  peculiar  animal  matter,  known  under 
the  name  of  mucosine.  When  unmixed  with  other  animal  fluids, 
this  viscidity  is  so  great  that  the  mucus  has  nearly  a  semi-solid  or 
gelatinous  consistency.  Thus,  the  mucus  of  the  mouth,  when  ob- 
tained unmixed  with  the  secretions  of  the  salivary  glands,  is  so 


SEBACEOUS    MATTER.  269 

tougli  and  adhesive  that  the  vessel  containing  it  may  be  turned 
upside  down  without  its  running  out.  The  mucus  of  the  cervix 
uteri  has  a  similar  firm  consistency,  so  as  to'  block  up  the  cavity 
of  this  part  of  the  organ  with  a  semi-solid  gelatinous  mass.  Mucus 
is  at  the  same  time  exceedingly  smooth  and  slippery  to  the  touch, 
so  that  it  lubricates  readily  the  surfaces  upon  which  it  is  exuded, 
and  facilitates  the  passage  of  foreign  substances,  while  it  defends 
the  mucous  membrane  itself  from  injury. 

The  composition  of  mucus,  according  to  the  analyses  of  Nasse,^ 
is  as  follows : — 

Composition  of  Pulmonary  Mucus. 

Water 955.52 

Animal  matter  ..........  33.57 

Fat 2.89 

Chloride  of  sodium    .........  5.83 

Phosphates  of  soda  and  potass           ......  1.05 

Sulphates        "                 " 0.65 

Carbonates      "                 " 0.49 

1000.00 

The  animal  matter  of  mucus  is  insoluble  in  water ;  and  conse- 
quently mucus,  when  dropped  into  water,  does  not  mix  with  it,  but 
is  merely  broken  up  by  agitation  into  gelatinous  threads  and  flakes, 
which  subside  after  a  time  to  the  bottom.  It  is  miscible,  however, 
to  some  extent,  with  other  animal  fluids,  and  may  be  incorporated 
with  them,  so  as  to  become  thinner  and  more  dilute.  It  readily 
takes  on  putrefactive  changes,  and  communicates  them  to  other 
organic  substances  with  which  it  may  be  in  contact. 

The  varieties  of  mucus  found  in  different  parts  of  the  body  are 
probably  not  identical,  but  differ  a  little  in  the  character  of  their 
principal  organic  ingredient,  as  well  as  in  the  proportions  of  their 
saline  constituents.  The  function  of  mucus  is  for  the  most  part  a 
physical  one,  viz.,  to  lubricate  the  mucous  surfaces,  to  defend  them 
from  injury,  and  to  facilitate  the  passage  of  foreign  substances 
through  their  cavities. 

2.  Sebaceous  Matter, — The  sebaceous  matter  is  distinguished 
by  containing  a  very  large  proportion  of  fatty  or  oily  ingredients. 
There  are  three  varieties  of  this  secretion  met  with  in  the  body, 
viz.,  one  produced  by  the  sebaceous  glands  of  the  skin,  another 
by  the  ceruminous  glands  of  the  external  auditory  meatus,  and 
a  third  by  the  Meibomian  glands  of  the  eyelid.     The  sebaceous 

'  Simon's  Chemistry  of  Man,  Philada.,  1846,  p.  352. 


270  SECRETION. 

glands  of  the  skin  are  found  most  abundantly  in  those  parts  which 
are  thickly  covered  with  hairs,  as  well  as  on  the  face,  the  labia 
minora  of  the  female  generative  organs,  the  glans  penis,  and  the 
prepuce.  They  consist  sometimes  of  a  simple  follicle,  or  flask- 
shaped  cavity,  opening  by  a  single  orifice ;  but  more  frequently  of 
a  number  of  such  follicles  grouped  round  a  common  excretory  duct. 
The  duct  nearly  always  opens  just  at  the  root  of  one  of  the  hairs, 

which  is  smeared  more  or  less  abundantly 
Fig-  103.  with  its  secretion.  Each  follicle,  as  in  the 

case  of  the  mucous  glandules,  is  lined 
with  epithelium,  and  its  cavity  is  filled 

yi^^  .i'"'^^*f^^^B      ^^^'^  ^^  secreted  sebaceous  matter. 
"?^'^'»"^V-  .^^H  In  the  Meibomian  glands  of  the  eye- 

pf   '-'>-  '^^*"'^^B     lid  (Fig.  103),  the  follicles  are  ranged 
''..      ,-     :' "  ^^H     along  the   sides  of  an  excretory   duet, 
y,  ,. '-'"i    '  .  ^^^H     situated  just  beneath  the  conjunctiva,  on 
|'£?  ;'    .1  '^'^'''^^B     th®  posterior  surface  of  the  tarsus,  and 
>'    "^    '"^   "*    i^^l     opening  upon  its  free  edge,  a  little  be- 
l^iiRJI^ffli^^H     ^i^d  *^®  roots   of  the  eyelashes.     The 
ceruminous  glands  of  the  external  audi- 
tory meatus,  again,  have  .the  form  of  long 
tubes,  which  terminate,  at  the  lower  part 

Meibomian      Glands,      after         o     ^        •  t     •  i 

Liidovic.  01  the  integument  Iming  the  meatus,  in 

a  globular  coil,  or  convolution,  covered 
externally  by  a  network  of  capillary  bloodvessels. 

The  sebaceous  matter  of  the  skin  has  the  following  composition, 
according  to  Esenbeck.' 

Composition  of  Sebaceous  Mattek. 

Animal  substances           .......  358 

Fatty  matters          ........  868 

Phosphate  of  lime  ........  200 

Carbonate  of  lime  ........  21 

Carbonate  of  magnesia  .......  16 

Chloride  of  sodium  ^ 

I                                           .           ■                 37 
Acetate  of  soda,  &c.  j       •         •         •         •  •         •       

1000 

Owing  to  the  large  proportion  of  stearine  in  the  fatty  ingredients 
of  the  sebaceous  matters,  they  have  a  considerable  degree  of  con- 
sistency. Their  office  is  to  lubricate  the  integument  and  the  hairs, 
to  keep  them  soft  and  pliable,  and  to  prevent  their  drying  up  by 


'  Simon's  Chemistry  of  Man,  p.  379. 


PEESPIRATION. 


271 


too  rapid  evaporation.  Wlien  the  sebaceous  glands  of  the  scalp 
are  inactive  or  atrophied,  the  hairs  become  dry  and  brittle,  are 
easily  split  or  broken  off,  and  finally  cease  growing  altogether. 
The  ceruminous  matter  of  the  ear  is  intended  without  doubt  partly 
to  obstruct  the  cavity  of  the  meatus,  and  by  its  glutinous  consist- 
ency and  strong  odor  to  prevent  small  insects  from  accidentally 
introducing  themselves  into  the  meatus.  The  secretion  of  the 
Meibomian  glands,  by  being  smeared  on  the  edges  of  the  eyelids, 
prevents  the  tears  from  running  over  upon  the  cheeks,  and  confines 
them  within  the  cavity  of  the  lachrymal  canals. 


Fiff.  104. 


3.  Perspiration. — The  perspiratory  glands  of  the  skin  are 
scattered  everywhere  throughout  the  integument,  being  most 
abundant  on  the  anterior  portions  of  the  body.  They  consist  each 
of  a  slender  tube,  about  -^l^  of  an  inch  in  diameter,  lined  with 
glandular  epithelium,  which  penetrates  nearly  through  the  entire 
thickness  of  the  skin,  and  terminates  below  in  a  globular  coil,  very 
similar  in  appearance  to  that  of 
the  ceruminous  glands  of  the  ear. 
(Fig.  104.)  A  network  of  capil- 
lary vessels  envelops  the  tubular 
coil  and  supplies  the  gland  with 
the  materials  necessary  to  its  se- 
cretion. 

These  glands  are  very  abundant 
in  some  parts.  On  the  posterior 
portion  of  the  trunk,  the  cheeks, 
and  the  skin  of  the  thigh  and  leg 
there  are,  according  to  Krause,* 
about  500  to  the  square  inch  ;  on 
the  anterior  part  of  the  trunk,  the 
forehead,  the  neck,  the  forearm, 
and  the  back  of  the  hand  and  foot 
1000  to  the  square  inch ;  and  on  the 
sole  of  the  foot  and  the  palm  of  the  hand  about  2700  in  the  same 
space.  According  to  the  same  observer,  the  whole  number  of  per- 
spiratory glands  is  not  less  than  2,300,000,  and  the  length  of  each 
tubular  coil,  when  unravelled,  about  y'g  of  an  inch.  The  entire 
length  of  the  glandular  tubing  must  therefore  be  not  less  than 
153,000  inches,  or  about  two  miles  and  a  half. 


A  Perspiratory  Gland,  -with  its  ves- 
sels;  magnified  35  times.  (After  Todd  and  Bow- 
man.)— a.  Glandular  coil.  6.  Plexus  of  vessels, 
c.   Excretory  duct. 


Kcilliker,  Handbucli  der  Gewebelelire,  Leipzig,  1852,  p.  147. 


272  SECEETioisr. 

It  is  easy  to  understand,  therefore,  that  a  very  large  quantity  of 
fluid  may  be  supplied  from  so  extensive  a  glandular  apparatus.  It 
results  from  the  researches  of  Lavoisier  and  Seguin^  that  the  ave- 
rage quantity  of  fluid  lost  by  cutaneous  perspiration  during  24 
hours  is  18,770  grains,  or  nearly  two  pounds  avoirdupois.  A  still 
larger  quantity  than  this  may  be  discharged  during  a  shorter  time, 
when  the  external  temperature  is  high  and  the  circulation  active. 
Dr.  Southwood  Smith^  found  that  the  laborers  employed  in  gas 
works  lost  sometimes  as  much  as  3  J  pounds'  weight,  by  both  cata- 
neous  and  pulmonary  exhalation,  in  less  than  an  hour.  In  these 
cases,  as  Seguin  has  shown,  the  amount  of  cutaneous  transpiration 
is  about  twice  as  great  as  that  which  takes  place  through  the  lungs. 

The  perspiration  is  a  colorless  watery  fluid,  generally  with  a 
distinctly  acid  reaction,  and  >  having  a  peculiar  odor,  which  varies 
somewhat  according  to  the  part  of  the  body  from  which  the  speci- 
men is  obtained.  Its  chemical  constitution,  according  to  Anselmino.^ 
is  as  follows : — 

C'JIPOSITION  OF  THE  PeKSPIBATION. 

Water 995.00 

Animal  matters,  with  lime  ........  .10 

Sulphates,  and  substances  soluble  in  water         ....  1.05 

Chlorides  of  sodium  and  potassium,  and  spirit-extract         .         .  2.40 

Acetic  acid,  acetates,  lactates,  and  alcohol-extract       .         .         .  1.45 


1000.00 


The  office  of  the  cutaneous  perspiration  is  principally  to  regulate 
the  temperature  of  the  body.  We  have  already  seen,  in  a  preced- 
ing chapter,  that  the  living  body  will  maintain  the  temperature  of 
100°  F.,  though  subjected  to  a  much  lower  temperature  by  the 
surrounding  atmosphere,  in  consequence  of  the  continued  genera- 
tion of  heat  which  takes  place  in  its  interior ;  and  that  if,  by  long 
continued  or  severe  exposure,  the  blood  become  cooled  down  much 
below  its  natural  standard,  death  inevitably  results.  But  the  body 
has  also  the  power  of  resisting  an  unnaturally  high  temperature, 
as  well  as  an  unnaturally  low  one.  If  exposed  to  the  influence  of 
an  atmosphere  warmer  than  100°  F.,  the  body  does  not  become 
heated  up  to  the  temperature  of  the  air,  but  remains  at  its  natural 
standard.  This  is  provided  for  by  the  action  of  the  cutaneous 
glands,  which  are  excited  to  unusual  activity,  and  pour  out  a  large 
quantity  of  watery  fluid  upon  the  skin.     This  fluid  immediately 

'  Robin  and  Verdeil.     Op.  cit.,  vol.  ii.  p.  145. 
^  Philosophy  of  Health,  London,  1838,  chap.  xiii. 
^  Simon.     Op.  cit.,  p.  374. 


THE    TEARS.  273 

evaporates,  and  in  assuming  the  gaseous  form  causes  so  much  heat 
to  become  latent  that  the  cutaneous  surfaces  are  cooled  down  to 
their  natural  temperature. 

.  So  long  as  the  air  is  dry,  so  that  evaporation  from  the  surface 
can  go  on  rapidly,  a  very  elevated  temperature  can  be  borne  with 
impunity.  The  workmen  of  the  sculptor  Chantrey  were  in  the 
habit,  according  to  Dr.  Carpenter,  of  entering  a  furnace  in  which 
the  air  was  heated  up  to  350°;  and  other  instances  have  been  known 
in  which  a  temperature  of  400°  to  600°  has  been  borne  for  a  time 
without  much  inconvenience.  But  if  the  air  be  saturated  with 
moisture,  and  evaporation  from  the  skin  in  this  way  retarded,  the 
body  soon  becomes  unnaturally  warm ;  and  if  the  exposure  be  long 
continued,  death  is  the  result.  It  is  easily  seen  that  horses,  when 
fast  driven,  suffer  much  more  from  a  warm  and  moist  atmosphere 
than  from  a  warm  and  dry  one.  The  experiments  of  Magendie  and 
others  have  shown'  that  quadrupeds  confined  in  a  dry  atmosphere 
suffer  at  first  but  little  inQonvenience,  even  when  the  temperature 
is  much  above  that  of  their  own  bodies ;  but  as  soon  as  the  atmo- 
sphere is  loaded  with  moisture,  or  the  supply  of  perspiration  is  ex- 
hausted, the  blood  becomes  heated,  and  the  animal  dies.  Death 
follows  in  these  cases  as  soon  as  the  blood  has  become  heated  up  to 
8°  or  9°  F.,  above  its  natural  standard.  The  temperature  of  110°, 
therefore,  which  is  the  natural  temperature  of  birds,  is  fatal  to  quad- 
rupeds ;  and  we  have  found  that  frogs,  whose  natural  temperature 
is  50°  or  60°,  die  very  soon  if  they  are  kept  in  water  at  100°  F. 

The  amount  of  perspiration  is  liable  to  variation,  as  we  have 
already  intimated,  from  the  variations  in  temperature  of  the  sur- 
rounding atmosphere.  It  is  excited  also  by  unusual  muscular 
exertion,  and  increased  or  diminished  by  various  nervous  condi- 
tions, such  as  anxiety,  irritation,  lassitude,  or  excitement. 

4.  The  Tears. — The  tears  are  produced  by  lobulated  glands 
situated  at  the  upper  and  outer  part  of  the  orbit  of  the  eye,  and 
opening,  by  from  six  to  twelve  ducts,  upon  the  surface  of  the  con- 
junctiva, in  the  fold  between  the  eyeball  and  the  outer  portion  of 
the  upper  lid.  The  secretion  is  extremely  watery  in  its  composition, 
and  contains  only  about  one  part  per  thousand  of  solid  matters, 
consisting  mostly  of  chloride  of  sodium  and  animal  extractive 
matter.     The  office  of  the  lachrymal  secretion  is  simply  to  keep  the 

'  Bernard,  Lectures  on  the  Blood.     Atlee's  translation,  p.  25. 

lb 


274 


SECRETION. 


surfaces  of  the  cornea  and  conjunctiva  moist  and  polished,  and  to 
preserve  in  this  way  the  transparency  of  the  parts.  The  tears, 
which  are  constantly  secreted,  are  spread  out  uniformly  over  the 
anterior  part  of  the  eyeball  by  the  movement  of  the  lids  in  wink- 
ing, and  are  gradually  conducted  to  the  inner  angle  of  the  eye. 
Here  they  are  taken  up  by  the  puncta  lachrymalia,  pass  through 
the  lachrymal  canals,  and  are  finally  discharged  into  the  nasal  pas- 
sages beneath  the  inferior  turbinated  bones.  A  constant  supply  of 
fresh  fluid  is  thus  kept  passing  over  the  transparent  parts  of  the 
eyeball,  and  the  bad  results  avoided  Avhich  would  follow  from  its 
accumulation  and  putrefactive  alteration. 

5.  The  Milk. — The  mammary  glands  are  conglomerate  glands, 
resembling  closely  in  their  structure  the  pancreas,  the  salivary,  and 
the  lachrymal  glands.  They  consist  of  numerous  secreting  sacs  or 
follicles,  grouped  together  in  lobules,  each  lobule  being  supplied 
with  a  common  excretory  duct,  which  joins  those  coming  from 

adjacent  parts  of  the  gland. 
(Fig.  105.)  In  this  way,  by 
their  successive  union,  they 
form  larger  branches  and 
trunks,  until  they  are  reduced 
in  numbers  to  some  15  or  20 
cylindrical  ducts,  the  lactife- 
rous ducts,  which  open  finally 
by  as  many  minute  orifices 
upon  the  extremity  of  the 
nipple. 

The  secretion  of  the  milk 
becomes  fairly  established  at 
the  end  of  ^two  or  three  days 
after  delivery,  though  the 
breasts  often  contain  a  milky 
fluid  during  the  latter  part  of  pregnancy.  At  first,  the  fluid  dis- 
charged from  the  nipple  is  a  yellowish  turbid  mixture,  which  is 
called  the  colostrum.  It  has  the  appearance  of  being  thinner  than 
the  milk,  but  chemical  examinations  have  shown'  that  it  really  con- 
tains a  larger  amount  of  solid  ingredients  than  the  perfect  secre- 
tion. When  examined  under  the  microscope  it  is  seen  to  contain, 
beside  the  milk-globules  proper,  a  large  amount  of  irregularly  glo- 


Gi.ANDULAR  Structure  of  Mamma. 


'  Lehmann,  op.  cit.,  vol.  ii.  p.  63. 


THE    MILK. 


275 


bular  or  oval  bodies,  from  y^^-go  to  ^^^  of  an  inch  in  diameter, 
which  are  termed  the  *'  colostrum  corpuscles."  (B'ig.  106.)  These 
bodies  are  more  yellow  and 
opaque  than  the  true  milk- 
globules,  as  well  as  being  very 
much  larger.  They  have  a 
well  defined  outline,  and  con- 
sist apparently  of  a  group  of 
minute  oily  granules  or  glo- 
bules, imbedded  in  a  mass 
of  organic  substance.  The 
milk-globules  at  this  time 
are  less  abundant  than  after- 
ward, and  of  larger  size, 
measuring  mostly  from  ^^'^^ 

to   Ys'oo   o^  ^^  ^^^^  ^^  ^'^' 
meter. 

At  the  end  of  a  day  or 
two  from  its  first  appearance 

the  colostrum  ceases  to  be  discharged,  and  is  replaced  by  the  true 
milky  secretion. 

The  milk,  as  it  is  discharged  from  the  nipple,  is  a  white,  opaque 
fluid,  with  a  slightly  alkaline  reaction,  and  a  specific  gravity  of 
about  1030.  Its  proximate  chemical  constitution,  according  to 
Pereira  and  Lehmann,  is  as  follows : — 

Composition  of  Cow's  Milk. 

.         .         .       9,1^.2 

44.8 

31.3 

47.7 

1 

Chlorides  of  sodium  and  potassium     ..... 

Phosphates  of  soda  and  potass    ......  i 

Pliosphate  of  lime 

"        "      magnesia 
"         "      iron 
Alkaline  carbonates     . 


Colostrum   Corpuscles,  with  milk-globules  ; 
from  a  woman,  one  day  after  delivery. 


Water 
Casein 
Butter 
Sugar 
Soda 


6.0 


1000.0 


Human  milk  is  distinguished  from  the  above  by  containing  less 
casein,  and  a  larger  proportion  of  oily  and  saccharine  ingredients. 
The  entire  amount  of  solid  ingredients  is  also  somewhat  less  than 
in  cow's  milk. 


276 


SECRETION. 


The  casein  is  one  of  the  most  important  ingredients  of  the  milk. 
It  is  an  extremely  nutritious,  organic  substance,  which  is  held  in  a 
fluid  form  by  union  with  the  water  of  the  secretion.  Casein  is  not 
coagulable  by  heat,  and,  consequently,  milk  may  be  boiled  without 
changing  its  consistency  to  any  considerable  extent.  It  becomes 
a  little  thinner  and  more  fluid  during  ebullition,  owing  to  the  melt- 
ing of  its  oleaginous  ingredients ;  and  a  thin,  membranous  film 
forms  upon  its  surface,  consisting  probably  of  a  very  little  albumen 
which  the  milk  contains,  mingled  with  the  casein.  The  addition  of 
any  of  the  acids,  however,  mineral,  animal,  or  vegetable,  at  once 
coagulates  the  casein,  and  the  milk  becomes  curdled.  Milk  is 
coagulated,  furthermore,  by  the  gastric  juice  in  the  natural  process 
of  digestion,  immediately  after  being  taken  into  the  stomach ;  and 
if  vomiting  occur  soon  after  a  meal  containing  milk,  it  is  thrown 
off  in  the  form  of  semi-solid,  curd-like  flakes. 

The  mucous  membrane  of  the  calves'  stomach,  or  rennet,  also 
has  the  power  of  coagulating  casein ;  and  when  milk  has  been 
curdled  in  this  way,  and  its  watery,  saccharine,  and  inorganic  in- 
gredients separated  by  mechanical  pressure,  it  is  converted  into 
cheese.  The  peculiar  flavor  of  the  different  varieties  of  cheese 
depends  on  the  quantity  and  quality  of  the  oleaginous  ingredients 
which  have  been  entangled  with  the  coagulated  casein,  and  on  the 

alterations  which  these  sub- 
Fig.  107.  stances  have  undergone  by 
the    lapse  of  time   and  ex- 
posure to  the  atmosphere. 

The  sugar  and  saline  sub- 
stances of  the  milk  are  in 
solution,  together  with  the 
casein  and  water,  forming  a 
clear,  colorless,  homogene- 
ous, serous  fluid.  The  but- 
ter, or  oleaginous  ingredient, 
however,  is  suspended  in 
this  serous  fluid  in  the  form 
of  minute  granules  and 
globules,  the  true  "milk 
globules."  (Fig.  107.)  These 
globules  are  nearly  fluid  at 
th3  temperature  of  the  body,  and  have  a  perfectly  circular  out- 
line.    In  the  perfect  milk,  they  are  very  much  more  abundant  and 


?o°o  o°o?  O.oo, 
o 


o°» 


@:J&ro^L 


a   o 

o°o 


^ol^.'o 


"  Oo 

'O  O  ^   O   O"^ 
oooo  O  O  o^  o'oo  °oO 

bPoOO     ZoOo    - 

-    o 


Milk-Globules;  from   same  woman  as   above, 
four  days  after  delivery.     Secretion  fully  established. 


THE    MILK.  277 

smaller  in  size  than  in  the  colostrum;  as  the  largest  of  them  are 

not  over  v^^V^  of  an  inch  in  diameter,  and  the   greater  number 

about  YxrrriyTT  of  an  inch. 

The  following  is  the  composition  of  the  butter  of  cow's  milk, 

according  to  Eobin  and  Verdeil: — 

Margarine   .         .         .         .         .         .         .         .         .         .68 

Oleine 30 

Butyrine      ..........       2 

100 

It  is  the  last  of  these  ingredients,  the  butyrine,  which  gives  the 
peculiar  flavor  to  the  butter  of  milk. 

The  niilk-globules  have  sometimes  been  described  as  if  each  one 
were  separately  covered  with  a  thin  layer  of  coagulated  casein  or 
albumen.  No  such  investing  membrane,  however,  is  to  be  seen. 
The  milk-globules  are  simply  small  masses  of  semi-fluid  fat,  sus- 
pended by  admixture  in  the  watery  and  serous  portions  of  the 
secretion,  so  as  to  make  an  opaque,  whitish  emulsion.  They  do 
not  fuse  together  when  they  come  in  contact  under  the  microscope, 
simply  because  they  are  not  quite  fluid,  but  contain  a  large  pro- 
portion of  margarine,  which  is  solid  at  ordinary  temperatures  of 
the  body,  and  is  only  retained  in  a  partially  fluid  form  by  the 
oleine  with  which  it  is  associated.  The  globules  may  be  made  to 
fuse  with  each  other,  however,  by  simply  heating  the  milk  and 
subjecting  it  to  gentle  pressure  between  two  slips  of  glass. 

"When  fresh  milk  is  allowed  to  remain  at  rest  for  twelve  to  twenty- 
four  hours,  a  large  portion  of  its  fatty  matters  rise  to  the  surface, 
and  form  there  a  dense  and  rich  looking  yellowish-white  layer,  the 
cream,  which  may  be  removed,  leaving  the  remainder  still  opaline, 
but  less  opaque  than  before.  At  the  end  of  thirty-six  to  forty-eight 
hours,  if  the  weather  be  warm,  the  casein  begins  to  take  on  a 
putrefactive  change.  In  this  condition  it  exerts  a  catalytic  action 
upon  the  other  ingredients  of  the  milk,  and  particularly  upon  the 
sugar.  A  pure  watery  solution  of  milk-sugar  {C^^S.^/)^)  may  be 
kept  for  an  indefinite  length  of  time,  at  ordinary  temperatures, 
without  undergoing  any  change.  But  if  kept  in  contact  with  the 
partially  altered  casein,  it  suffers  a  catalytic  transformation,  and  is 
converted  into  lactic  acid  (CgHgOg).  This  unites  with  the  free  soda, 
and  decomposes  the  alkaline  carbonates,  forming  lactates  of  soda 
and  potass.  After  the  neutralization  of  these  substances  has  been 
accomplished,  the  milk  loses  its  alkaline  reaction  and  begins  to  turn 
sour.     The  free  lactic  acid  then  coagulates  the  casein,  and  the  milk 


278  SECRETION. 

is  curdled.  The  altered  organic  matter  also  acts  upon  the  oleagi- 
nous ingredients,  which  are  partly  decomposed;  and  the  milk 
begins  to  give  off  a  rancid  odor,  owing  to  the  development  of 
various  volatile  fatty  acids,  among  which  are  butyric  acid,  and  the 
like.  These  changes  are  very  much  hastened  by  a  moderately 
elevated  temperature,  and  also  by  a  highly  electric  state  of  the 
atmosphere. 

The  production  of  the  milk,  like  that  of  other  secretions,  is  liable 
to  be  much  influenced  by  nervous  impressions.  It  may  be  increased 
or  diminished  in  quantity,  or  vitiated  in  quality  by  sudden  emo- 
tions ;  and  it  is  even  said  to  have  been  sometimes  so  much  altered 
in  this  way  as  to  produce  indigestion,  diarrhoea,  and  convulsions  in 
the  infant. 

Simon  found'  that  the  constitution  of  the  milk  varies  from  day  to 
day,  owing  to  temporary  causes ;  and  that  it  undergoes  also  more 
permanent  modifications,  corresponding  with  the  age  of  the  infant. 
He  analyzed  the  milk  of  a  nursing  woman  during  a  period  of  nearly 
six  months,  commencing  with  the  second  day  after  delivery,  and 
repeating  his  examinations  at  intervals  of  eight  or  ten  days.  It 
appears,  from  these  observations,  that  the  casein  is  at  first  in  small 
quantity ;  but  that  it  increases  during  the  first  two  months,  and 
then  attains  a  nearly  uniform  standard.  The  saline  matters  also 
increase  in  a  nearly  similar  manner.  The  sugar,  on  the  contrary, 
diminishes  during  the  same  period ;  so  that  it  is  less  abundant  in 
the  third,  fourth,  fifth  and  sixth  months,  than  it  is  in  the  first  and 
second.  These  changes  are  undoubtedly  connected  with  the  in- 
creasing development  of  the  infant,  which  requires  a  corresponding 
alteration  in  the  character  of  the  food  supplied  to  it.  Finally,  the 
quantity  of  butter  in  the  milk  varies  so  much  from  day  to  day, 
owing  to  incidental  causes,  that  it  cannot  be  said  to  follow  any 
regular  course  of  increase  or  diminution. 

6.  Secretion  of  the  Bile. — The  anatomical  peculiarities  in  the 
structure  of  the  liver  are  such  as  to  distinguish  it  in  a  marked 
degree  from  the  other  glandular  organs.  Its  first  peculiarity  is 
that  it  is  furnished  principally  with  venous  blood.  For,  although 
it  receives  its  blood  from  the  hepatic  artery  as  well  as  from  the 
portal  vein,  the  quantity  of  arterial  blood  with  which  it  is  supplied 
is  extremely  small  in  comparison  with  that  which  it  receives  from 

'  Op.  cit.,  p.  337. 


SECRETION    OF    THE    BILE. 


279 


the  portal  system.  The  blood  which  has  circulated  through  the 
capillaries  of  the  stomach,  spleen,  pancreas,  and  intestine  is  collected 
by  the  roots  of  the  corresponding  veins,  and  is  discharged  into  the 
great  portal  vein,  which  enters  the  liver  at  the  great  transverse 
fissure  of  the  organ.  Immediately  upon  its  entrance,  the  portal 
vein  divides  into  two  branches,  right  and  left,  which  supply  the 
corresponding  portions  of  the  liver ;  and  these  branches  success- 
ively subdivide  into  smaller  twigs  and  ramifications,  until  they  are 
reduced  to  the  size,  according  to  Kolliker,  of  ysVo  of  ^^  i^ch  in 
diameter.  These  veins,  with  their  terminal  branches,  are  now 
arranged  in  such  a  manner  as  to  include  between  them  pentagonal 
or  hexagonal  spaces,  or  portions  of  the  hepatic  substance  g'g  to  Jg 
of  an  inch  in  diameter  in  the  human  subject,  which  can  readily  be 
distinguished  by  the  naked  eye,  both  on  the  exterior  of  the  organ 
and  by  the  inspection  of  cut  surfaces.  The  portions  of  hepatic 
substance  included  in  this  way  between  the  terminal  branches  of 
the  portal  vein  (Fig.  108)  are 

termed    the    "  acini"    or   the  Fig-  108. 

"lobules"  of  the  liver;  and 
the  terminal  venous  branches, 
occupying  the  spaces  between 
the  adjacent  lobules,  are  the 
"  interlobular"  veins.  In  the 
spaces  between  the  lobules 
we  also  find  the  minute 
branches  of  the  hepatic  ar- 
tery, and  ,the  commencing 
rootlets  of  the  hepatic^ducts. 
As  the  portal  vein,  the  he- 
patic artery,  and  the  hepatic 
duct  enter  the  liver  at  the 

n  -I  Ramification  of    Portal  Ye  IN    in    Livkk. — a. 

transverse     riSSUre,    they    are       Twig  of  poital  vein.   &,  6.  interlobular  veins,  c.  Acini. 

closely  invested  by  a  fibrous 

sheath,  Glisson's  capsule,  which  accompanies  them  in  their  divisions 
and  ramifications.  In  some  of  the  lower  animals,  as  in  the  pig, 
this  sheath  extends  even  to  the  interlobular  spaces,  inclosing  each 
lobule  in  a  -thin  fibrous  investment,  by  which  it  is  distinctly 
separated  from  the  neighboring  parts.  In  the  human  subject,  how- 
ever, Glisson's  capsule  becomes  gradually  thinner  as  it  penetrates 
the  liver,  and  disappears  altogether  before  reaching  the  interlobular 
spaces;  so  that  here  the  lobules  are  nearly  in  contact  with  each 


280  SECEETION. 

other  by  their  adjacent  surfaces,  being  separated  only  by  the  inter- 
lobular veins  and  the  minute  branches  «['  the  hepatic  artery  and 
duct  previously  mentioned. 

From  the  sides  of  the  interlobular  veins,  and  also  from  their 
terminal  extremities,  there  are  given  oft'  capillary  vessels,  which 
penetrate  the  substance  of  each  lobule  and  converge  from  its  cir- 
cumference toward  its  centre,  inosculating  at  the  same  time  freely 
with  each  other,  so  as  to  form  a  minute  vascular  plexus,  the  "  lobu- 
lar" capillary  plexus.  (Fig.  109.)     At  the  centre  of  each  lobule,  the 

Fig.  109. 


Lobule  of  Liver,  showing  distribution  of  bloodvessels;  magnified  22  diameters — a,  a.  In- 
terlobular veins.  6.  Intralobular  vein,  c,  c,  c.  Lobular  capillary  plexus,  d,  d.  Twigs  of  inter- 
lobular vein  passing  to  adjacent  lobules. 

converging  capillaries  unite  into  a  small  vein  (b),  the  "  intralobu- 
lar" vein,  which  is  one  of  the  commencing  rootlets  of  the  hepatic 
vein.  These  rootlets,  uniting  successivelj''  with  each  other,  so  as 
to  form  larger  and  larger  branches,  finally  leave  the  liver  at  its 
posterior  edge,  to  empty  into  the  ascending  vena  cava. 

Beside  the  capillary  bloodvessels  of  the  lobular  plexus,  each 
acinus  is  made  up  of  an  abundance  of  minute  cellular  bodies,  about 
T2V0  of  an  inch  in  diameter,  the  "hepatic  cells."  (Fig.  110.)  These 
cells  have  an  irregularly  pentagonal  figure,  and  a  soft  consistency. 
They  are  composed  of  a  homogeneous  organic  substance,  in  the 
midst  of  which  are  imbedded  a  large  number  of  minute  granules, 
and  generally  several  well  defined  oil-globules.  There  is  also  a 
round  or  oval  nucleus,  with  a  nucleolus,  imbedded  in  the  substance 


SECRETION    OF    THE    BILE. 


281 


of  the  cell,  sometimes  more  or  less  obscured  bj  the  granules  and 
oil  drops  with  which  it  is  surrounded. 

The  exact  mode  in  which  these  cells  are  connected  with  the 
hepatic  duct  was  for  a  long  time  the  most  obscure  point  in  the 
minute  anatomy  of  the  liver. 

It  has  now  been  ascertained,  Fig.  110. 

however,  by  the  researches  of 
Dr.  Leidy,  of  Philadelphia,' 
and  Dr.  Beale,  of  London,^ 
that  they  are  really  contained 
in  the  interior  of  secreting 
tubules,  which  pass  off  from 
the  smaller  hepatic  ducts,  and 
penetrate  everywhere  the 
substance  of  the  lobules. 
The  cells  fill  nearly  or  com- 
pletely the  whole  cavity  of 
the  tubules,  and  the  tubules 
themselves  lie  in  close  proxi- 
mity with  each  other,  so  as 
to  leave  no  space  between  them  except  that  which  is  occupied  by 
the  capillary  bloodvessels  of  the  lobular  plexus. 

These  cells  are  the  active  agents  in  accomplishing  the  function  of 
the  liver.  It  is  by  their  influence  that  the  blood  which  is  brought 
in  contact  with  them  suffers  certain  changes  which  give  rise  to  the 
secreted  products  of  the  organ.  The  ingredients  of  the  bile  first 
make  their  appearance  in  the  substance  of  the  cells.  They  are 
then  transuded  from  one  to  the  other,  until  they  are  at  last  dis- 
charged into  the  small  biliary  ducts  seated  in  the  interlobular 
spaces.  Each  lobule  of  the  liver  must  accordingly  be  regarded  as 
a  mass  of  secreting  tubules,  lined  with  glandular  cells,  and  invested 
with  a  close  network  of  capillary  bloodvessels.  It  follows,  there- 
fore, from  the  abundant  inosculation  of  the  lobular  capillaries,  and 
the  manner  in  which  they  are  entangled  with  the  hepatic  tissue, 
that  the  blood,  in  passing  through  the  circulation  of  the  liver, 
comes  into  the  most  intimate  relation  with  the  glandular  cells  of 
the  organ,  and  gives  up  to  them  the  nutritious  materials  which  are 
afterward  converted  into  the  iuOTedients  of  the  bile. 


Hepatic   Cells.     From  the  human  subject. 


American  Journal  Med.  Sci.,  January,  1848. 

On  Some  Points  in  the  Minute  Anatomy  of  tlie  Liver. 


London, 1856. 


282  EXCKETION 


CHAPTER   XVI. 

EXCRETION. 

"We  have  now  come  to  the  last  division  of  the  great  nutritive 
function,  viz.,  the  process  of  excretion.  In  order  to  understand  fairly 
the  nature  of  this  process  we  must  remember  that  all  the  component 
parts  of  a  living  organism  are  necessarily  in  a  state  of  constant 
change.  It  is  one  of  the  essential  conditions  of  their  existence  and 
activity  that  they  should  go  through  with  this  incessant  transforma- 
tion and  renovation  of  their  component  substances.  Every  living 
animal  and  vegetable,  therefore,  constantly  absorbs  certain  materials 
from  the  exterior,  which  are  modified  and  assimilated  by  the  pro- 
cess of  nutrition,  and  converted  into  the  natural  ingredients  of  the 
organized  tissues.  But  at  the  same  time  with  this  incessant  growth 
and  supply,  there  goes  on  in  the  same  tissues  an  equally  incessant 
process  of  waste  and  decomposition.  For  though  the  elements  of 
the  food  are  absorbed  by  the  tissues,  and  converted  into  musculine, 
osteine,  haematine  and  the  Hire,  they  do  not  remain  permanently  in 
this  condition,  but  almost  immediately  begin  to  pass  over,  by  a  con- 
tinuance of  the  alterative  process,  into  new  forms  and  combinations, 
which  are  destined  to  be  expelled  from  the  body,  as  others  continue 
to  be  absorbed.  Thus  Spallanzani  and  Edwards  found  that  every 
organized  tissue  not  only  absorbs  oxygen  from  the  atmosphere 
and  fixes  it  in  its  own  substance;  but  at  the  same  time  exhales 
carbonic  acid,  which  has  been  produced  by  internal  metamorphosis. 
This  process,  by  which  the  ingredients  of  the  organic  tissues,  al- 
ready formed,  are  decomposed  and  converted  into  new  substances, 
is  called  the  process  of  Destructive  Assimilation. 

Accordingly  we  find  that  certain  substances  are  constantly  mak- 
ing their  appearance  in  the  tissues  and  fluids  of  the  body,  which 
did  not  exist  there  originally,  and  which  have  not  been  introduced 
with  the  food,  but  which  have  been  produced  by  the  process  of  in- 
ternal metamorphosis.  These  substances  represent  the  waste,  or 
physiological  detritus  of  the  animal  organism.    They  are  the  forms 


EXCRETION,  283 

under  wbich  those  materials  present  themselves,  which  have  once 
formed  a  part  of  the  living  tissues,  but  which  have  become  altered 
by  the  incessant  changes  characteristic  of  organized  bodies,  and 
which  are  consequently  no  longer  capable  of  exhibiting  vital  pro- 
perties, or  of  performing  the  vital  functions.  They  are,  therefore, 
destined  to  be  removed  and  discharged  from  the  animal  frame,  and 
are  known  accordingly  by  the  name  oi  Excrementitious  Substances. 

These  excrementitious  substances  have  peculiar  characters  by 
which  they  may  be  distinguished  from  the  other  ingredients  of  the 
living  body;  and  they  might,  therefore,  be  made  to  constitute  a 
fourth  class  of  proximate  principles,  in  addition  to  the  three  which 
we  have  enumerated  in  the  preceding  chapters.  They  are  all  sub- 
stances of  definite  chemical  composition,  and  all  susceptible  of 
crystallization.  Some  of  the  most  important  of  them  contain  nitro- 
gen, while  a  few  are  non-nitrogenous  in  their  composition.  They 
originate  in  the  interior  of  living  bodies,  and  are  not  found  else- 
where, except  occasionally  as  the  result  of  decomposition.  They 
are  nearly  all  soluble  in  water,  and  are  soluble  without  exception  in 
the  animal  fluids.  They  are  formed  in  the  substance  of  the  tissues, 
from  which  they  are  absorbed  by  the  blood,  to  be  afterward  conveyed 
by  the  circulating  fluid  to  certain  excretory  organs,  particularly  the 
kidneys,  from  which  they  are  finally  discharged  and  expelled  from 
the  body.  This  entire  process,  made  np  of  the  production  of  the 
excrementitious  substances,  their  absorption  by  the  blood,  and  their 
final  elimination,  is  known  as  the  process  of  excretion. 

The  importance  of  this  process  to  the  maintenance  of  life  is  readily 
shown  by  the  injurious  effects  which  follow  upon  its  disturbance. 
If  the  discharge  of  the  excrementitious  substances  be  in  any  way 
impeded  or  suspended,  these  substances  accumulate,  either  in  the 
blood  or  in  the  tissues  or  in  both.  In  consequence  of  this  retention 
and  accumulation,  they  become  poisonous,  and  rapidly  produce  a 
derangement  of  the  vital  functions.  Their  influence  is  principally 
exerted  upon  the  nervous  system,  through  which  they  produce 
most  frequently  irritability,  disturbance  of  the  special  senses,  deli- 
rium, insensibility,  coma,  and  finally  death.  The  readiness  with 
which  these  effects  are  produced  depends  on  the  character  of  the 
excrementitious  substance,  and  the  rapidity  with  whicli  it  is  pro- 
duced in  the  body.  Thus,  if  the  elimination  of  carbonic  acid  be 
stopped,  by  overloading  the  atmosphere  with  an  abundance  of  the 
same  gas,  death  takes  place  at  the  end  of  a  few  minutes ;  but  if  the 
elimination  of  urea  by  the  kidneys  be  checked,  it  requires  three  or 


284 


EXCRETION. 


four  days  to  produce  a  fatal  result.  A  fatal  result,  however,  is  cer- 
tain to  follow,  at  the  end  of  a  longer  or  shorter  time,  if  any  one  of 
these  substances  be  compelled  to  remain  in  the  body,  and  accumu- 
late in  the  animal  tissues  and  fluids. 

The  principal  excrementitious  substances  known  to  exist  in  the 
human  body  are  as  follows ; 


1.  Carbonic  acid 

2.  Cholesterine 

3.  Urea  . 

4.  Creatine 

5.  Creatinine  . 

6.  Urate  of  soda 

7.  Urate  of  potass 

8.  Urate  of  ammon 


CO, 

C2  H2,0 

C^H.N^O^ 

C.HgNaO, 

CgH.NjO.^ 

NaO.C.HN^Oj+HO 

KO.CjHN.O^ 

NH,0,2C5HN202-fHO 


Of  these  substances  the  first  two  have  already  been  studied  at 
sufficient  length  in  the  preceding  chapters.  We  will  merely  repeat 
here  that  carbonic  acid  is  produced  in  large  quantity  in  nearly  all 
the  tissues  of  the  body,  from  which  it  is  absorbed  by  the  blood, 
conveyed  to  the  lungs,  and  there  exhaled  at  the  sarrie  time  that 
oxygen  is  absorbed.  Cholesterine  is  a  non-saponifiable  fatty  sub- 
stance, originating  in  the  brain  and  spinal  cord,  in  the  tissue  of 
which  organs  it  exists  in  the  proportion  of  58  parts  per  thousand. 
It  is  thence  taken  up  by  the  blood,  conveyed  to  the  liver  and  dis- 
charged with  the  bile.  Cholesterine  is  extremely  insoluble  in 
water,  but  is  held  in  solution  in  the  blood  and  the  bile,  by  some  of 
the  other  ingredients  present  in  these  animal  fluids. 

The  remaining  excrementitious  substances  ma}^  be  examined 
together,  with  the  more  propriety,  since  they  are  all  ingredients  of 
a  single  excretory  fluid,  viz.,  the  urine. 


UREA. 


This  is  a  neutral,  crystallizable,  nitrogenous  substance,  very 
readily  soluble  in  water,  and  easily  decomposed  by  various  external 
influences.  It  occurs  in  the  urine  in  the  proportion  of  30  parts 
per  thousand;  and  in  the  blood  in  much  smaller  quantity.  The 
blood,  however,  is  the  source  from  which  this  substance  is  sup- 
plied to  the  urine ;  and  it  exists,  accordingly,  in  but  small  quantity 
in  the  circulating  fluid,  for  the  reason  that  it  is  constantly  drained 
off  by  the  kidneys.  But  if  the  kidneys  be  extirpated,  or  the  renal 
arteries  tied,  or  the  excretion  of  urine  suspended  by  inflammation 


UEEA. 


285 


or  otherwise,  the  urea  then  accumulates  in  the  blood,  and  presents 
itself  there  in  considerable  quantity.     It  has  been  found  in  the 
blood,    under    these    circum- 
stances, in  the    proportion  of  Fig-  m. 
1.4   per   thousand.'     It  is  not 
yet  known  from  what  source 
the  urea  is  originally  derived  ; 
whether  it  be  produced  in  the 
blood   itself,  or  whether  it  be 
formed  in   some  of   the  solid 
tissues,  and  thence  taken  up  by 
the  blood.    It  has  not  yet  been 
found,  however,  in  any  of  the 
solid  tissues,  in  a  state  of  health. 

Urea  is  obtained  most  readily 
from  the  urine.  For  this  pur- 
pose the  fresh  urine  is  evapo- 
rated, in  the  water  bath  until  it 

has  a  syrupy  consistency.  It  is  then  mixed  with  an  equal  volume  of 
nitric  acid,  which  forms  nitrate  of  urea.  This  salt,  being  less  soluble 
than  pure  urea,  rapidly  crystallizes,  after  which  it  is  separated  by 
filtration  from  the  other  ingredients.  It  is  then  dissolved  in  water 
and  decomposed  by  carbonate  of  lead,  forming  nitrate  of  lead  which 
remains  in  solution,  and  carbonic  acid  which  escapes.  The  solution 
is  then  evaporated,  the  urea  dissolved  out  by  alcohol,  and  finally 
crystallized  in  a  pure  state. 

Urea  has  no  tendency  to  spontaneous  decomposition,  and  may 
be  kept,  when  perfectly  pure,  in  a  dry  state  or  dissolved  in  water, 
for  an  indefinite  length  of  time.  If  the  watery  solution  be  boiled, 
however,  the  urea  is  converted,  during  the  process  of  ebullition, 
into  carbonate  of  ammonia.  One  equivalent  of  urea  unites  with 
two  equivalents  of  water,  and  becomes  transformed  into  two  equiva- 
lents of  carbonate  of  ammonia,  as  follows : — 


Urea,  prepared  from  urine,  and  crystallized  by 
slow  evaporation.     (After  Lehmann.) 


C,H^N202=Urea. 
H,    0,=Water. 


NH3,C02=Carbonate  of  ammonia. 

2 


Various  impurities,  also,  by  acting  as  catalytic  bodies,  will  in- 
duce the  same  change,  if  water  be  present.  Animal  substances  in 
a  state  of  commencing  decomposition  are  particularly  liable  to  act 


Robin  and  Verdeil,  vol.  ii.  p.  502. 


286  EXCRETION. 

in  this  way.  In  order  that  the  conversion  of  the  urea  be  thus 
produced,  it  is  necessary  that  the  temperature  of  the  mixture  be 
not  far  from  70°  to  100°  F. 

The  quantity  of  urea  produced  and  discharged  daily  by  a  healthy 
adult  is,  according  to  the  experiments  of  Lehmann,  about  500 
grains.  It  varies  to  some  extent,  like  all  the  other  secreted  and 
excreted  products,  with  the  size  and  development  of  the  body. 
Lehmann,  in  experiments  on  his  own  person,  found  the  average 
daily  quantity  to  be  487  grains.  Dr.  William  A.  Hammond,'  of 
the  U.  S.  Array,  who  is  a  very  large  man,  by  similar  experiments 
found  it  to  be  670  grains.  Dr.  John  C.  Draper'^  found  it  408 
grains.  No  urea  is  to  be  detected  in  the  urine  of  very  young 
children  ;^  but  it  soon  makes  its  appearance,  and  afterward  increases 
in  quantity  with  the  development  of  body. 

The  daily  quantity  of  urea  varies  also  with  the  degree  of  mental 
and  bodily  activity.  Lehmann  and  Hammond  both  found  it  very 
sensibly  increased  by  muscular  exertion  and  diminished  by  repose. 
It  has  been  thought,  from  these  facts,  that  this  substance  must  be 
directly  produced  from  disintegration  of  the  muscular  tissue.  This, 
however,  is  by  no  means  certain ;  since  in  a  state  of  general  bodily 
activity  it  is  not  only  the  urea,  but  the  excretions  generally,  carbonic 
acid,  perspiration,  &c.,  which  are  increased  in  quantity  simultane- 
ously with  each  other.  Hammond  has  also  shown  that  continued 
mental  application  will  raise  the  quantity  of  urea  above  its  normal 
standard,  though  the  muscular  system  remain  comparatively  in- 
active. 

The  quantity  of  urea  varies  also  with  the  nature  of  the  food. 
Lehmann,  by  experiments  on  his  own  person,  found  that  the  quan- 
tity was  larger  while  living  exclusively  on  animal  food  than  with 
a  mixed,  or  vegetable  diet ;  and  that  its  quantity  was  smallest  when 
confined  to  a  diet  of  purely  non-nitrogenous  substances,  as  starch, 
sugar,  and  oil.  The  following  table*  gives  the  result  of  these  ex- 
periments. 

Kind  of  Food.  Daily  Quantity  of  Urea. 

Animal 798  grains. 

Mixed 487       " 

Vegetable 337       " 

Non-nitrogenous         ......         231       " 

'  American  Journal  Med.  Sci.,  Jan.,  1855,  and  April,  1856. 

^  New  York  Journal  of  Medicine,  March,  1856. 

^  Robin  and  Veideil,  vol.  ii.  p.  500. 

''  Lehmann,  op.  cit.,  vol.  ii.  p.  163. 


CREATINE, 


287 


Finally,  it  has  been  shown  by  Dr.  John  C.  Draper'  that  there  is 
also  a  diurnal  variation  in  the  normal  quantity  of  urea.  A  smaller 
quantity  is  produced  during  the  night  than  during  the  day ;  and 
this  difference  exists  even  in  patients  who  are  confined  to  the  bed 
during  the  whole  twenty-four  hours,  as  in  the  case  of  a  man  under 
treatment  for  fracture  of  the  leg.  This  is  probably  owing  to  the 
greater  activity,  during  the  waking  hours,  of  both  the  mental  and 
digestive  functions.  More  urea  is  produced  in  the  latter  half  than 
in  the  earlier  half  of  the  day;  and  the  greatest  quantity  is  dis- 
charged during  the  four  hours  from  6|  to  lOJ  P.  M. 

Urea  exists  in  the  urine  of  the  carnivorous  and  many  of  the 
herbivorous  quadrupeds ;  but  there  is  little  or  none  to  be  found  in 
that  of  birds  and  reptiles. 


CREATINE. 

This  is  a  neutral  crystallizable  substance,  found  in  the  muscles, 
the  blood,  and  the  urine.  It  is  soluble  in  water,  very  slightly  solu- 
ble in  alcohol,  and  not  at  all 

so  in  ether.     By  boiling  with  ^'S*  ^^?: 

an  alkali,  it  is  either  converted 
into  carbonic  acid  and  ammonia, 
or  is  decomposed  with  the  pro- 
duction of  urea  and  an  artificial 
nitrogenous  crystallizable  sub- 
stance, termed  sarcosine.  By 
being  heated  with  strong  acids, 
it  loses  two  equivalents  of  water, 
and  is  converted  into  the  sub- 
stance next  to  be  described,  viz., 
creatinine. 

Creatine  exists  in  the  urine, 
in  the  human  subject,  in  the 
proportion  of  about  1.25  parts, 

and  in  the  muscles  in  the  proportion  of  0.67  parts  per  thousand. 
Its  quantity  in  the  blood  has  not  been  determined.  In  the  muscu- 
lar tissue  it  is  simply  in  solution  in  the  interstitial  fluid  of  the  parts, 
so  that  it  may  be  extracted  by  simply  cutting  the  muscle  into 


Creatine,  crystallized  from  hot  water.   (After 
Lehmauu  ) 


'  Loc.  cit. 


288 


EXCRETION. 


small  pieces,  treating  it  with  distilled  water,  and  subjecting  it  to 
pressure.  Creatine  evidently  originates  in  the  muscular  tissue,  is 
absorbed  thence  bj  the  blood,  and  is  finally  discharged  with  the 


urine. 


CREATININE. 

This  is  also  a  crystallizable  substance.  It  differs  in  composition 
from  creatine  by  containing  two  equivalents  less  of  the  elements 
of  water.  It  is  more  soluble  in  water  and  in  spirit  than  creatine, 
and  dissolves  slightly  also  in  ether.  It  has  a  distinctly  alkaline 
reaction.  It  occurs,  like  crea- 
tine, in  the  muscles,  the  blood,  §' 
and  the  urine ;  and  is  undoubt- 
edly first  produced  in  the 
muscular  tissue,  to  be  dis- 
charged finally  by  the  kidneys. 
It  is  very  possible  that  it  ori- 
ginates, not  directly  from  the 
muscles,  but  indirectly,  by  trans- 
formation of  a  part  of  the  crea- 
tine; since  it  may  be  artificially 
produced,  as  we  have  already 
mentioned,  by  transformation 
of  the  latter  substance  under 
the  influence  of  strong  acids, 
and  since,  furthermore,  while 
creatine  is  more  abundant  in  the  muscles  than  creatinine,  in  the 
urine,  on  the  contrary,  there  is  a  larger  quantity  of  creatinine  than 
of  creatine.  Both  these  substances  have  been  found  in  the  muscles 
and  in  the  urine  of  the  lower  animals. 


C  RE  AT  IX  IN  E,    crystallized    from    hot   water. 
(Afier  Lehmann.) 


URATE  OF  SODA. 


As  its  name  implies,  this  substance  is  a  neutral  salt,  formed  by 
the  union  of  soda,  as  a  base,  with  a  nitrogenous  animal  acid,  viz., 
uric  acid  {G^^Jd^^O).  Uric  acid  is  sometimes  spoken  of  as  though 
it  were  itself  a  proximate  principle,  and  a  constituent  of  the  urine; 
but  it  cannot  properly  be  regarded  as  such,  since  it  never  occurs  in 


URATES    OF    POTASS    AND    AMMONIA. 


289 


a  free  state,  in  a  natural  condition  of  the  fluids.     When  present,  it 
has  always  been  produced  by  decomposition  of  the  urate  of  soda. 

Urate  of  soda  is  readily  soluble  in  hot  water,  from  which  a  large 
portion  again  deposits  on  cooling.     It  is  slightly  soluble  in  alcohol, 
and   insoluble  in    ether.     It 
crystallizes  in  small  globular  '^" 

masses,  with  projecting,  curv- 
ed, conical,  wart-like  excres- 
cences. (Fig.  114.)  It  dis- 
solves readily  in  the  alkalies; 
and  by  most  acid  solutions  it 
is  decomposed,  with  the  pro- 
duction of  free  nric  acid. 

Urate  of  soda  exists  in  the 
urine  and  in  the  blood.  It  is 
either  produced  originally  in 
the  blood,  or  is  formed  in 
some  of  the  solid  tissues,  and 
absorbed  from  them  by  the 
circulating  fluid.  It  is  con- 
stantly eliminated  by  the  kidneys,  in  company  with  the  other  ingre- 
dients of  the  urine.  The  average  daily  quantity  of  urate  of  soda 
discharged  by  the  healthy  human  subject  is,  according  to  Lehmann, 
about  25  grains.  This  substance  exists  in  the  urine  of  the  carnivo- 
rous and  omnivorous  animals,  but  not  in  that  of  the  herbivora. 
In  the  latter,  it  is  replaced  by  another  substance,  differing  some- 
what from  it  in  composition  and  properties,  viz.,  hippurate  of  soda. 
The  urine  of  herbivora,  however,  while  still  very  young,  and  living 
upon  the  milk  of  the,  mother,  has  been  found  to  contain  urates. 
But  when  the  young  animal  is  weaned,  and  becomes  herbivorous, 
the  urate  of  soda  disappears,  and  is  replaced  by  the  hippurate. 


TJeate   of   Soda:   from  a  urinary  deposit. 


URATES  OF  POTASS  AND  AMMONIA. 


The  urates  of  potass  and  ammonia  resemble  the  preceding  salt 
very  closely  in  their  physiological  relations.  They  are  formed  in 
very  much  smaller  quantity  than  the  urate  of  soda,  and  appear  like 
it  as  ingredients  of  the  urine. 

The  substances  above  enumerated  resemble  each  other  closely  in 
19 


290  EXCRETION. 

their  most  striking  and  important  characters.  They  all  contain 
nitrogen,  are  all  crystallizable,  and  all  readily  soluble  in  water. 
They  all  originate  in  the  interior  of  the  body  by  the  decomposition 
or  catalytic  transformation  of  its  organic  ingredients,  and  are  all 
conveyed  by  the  blood  to  the  kidneys,  to  be  finally  expelled  with 
the  urine.  These  are  the  substances  which  represent,  to  a  great 
extent,  the  final  transformation  of  the  organic  or  albuminoid  in- 
gredients of  the  tissues.  It  has  already  been  mentioned,  in  a  pre- 
vious chapter,  that  these  organic  or  albuminoid  substances  are  not 
discharged  from  the  body,  under  their  own  form,  in  quantity  at  all 
proportionate  to  the  abundance  with  which  they  are  introduced. 
By  far  the  greater  part  of  the  mass  of  the  frame  is  made  up  of 
organic  substances:  albumen,  musculine,  osteine,  &c.  Similar 
materials  are  taken  daily  in  large  quantity  with  the  food,  in  order 
to  supply  the  nutrition  and  waste  of  those  already  composing  the 
tissues;  and  yet  only  a  very  insignificant  quantity  of  similar 
material  is  expelled  with  the  excretions.  A  minute  proportion  of 
volatile  animal  matter  is  exhaled  with  the  breath,  and  a  minute 
proportion  also  with  the  perspiration.  A  very  small  quantity  is 
discharged  under  the  form  of  mucus  and  coloring  matter,  with  the 
urine  and  feces ;  but  all  these  taken  together  are  entirely  insuffi- 
cient to  account  for  the  constant  and  rapid  disappearance  of  organic 
matters  in  the  interior  of  the  body.  These  matters,  in  fact,  before 
being  discharged,  are  converted  by  catalysis  and  decomposition  into 
new  substances.  Carbonic  acid,  under  which  form  3500  grains  of 
carbon  are  daily  expelled  from  the  body,  is  one  of  these  substances  ; 
the  others  are  urea,  creatine,  creatinine,  and  the  urates. 

We  see,  then,  in  what  way  the  organic  matters,  in  ceasing  to 
form  a  part  of  the  living  body,  lose  their  characteristic  properties, 
and  are  converted  into  crystallizable  substances,  of  definite  chemical 
composition.  It  is  a  kind  of  retrograde  metamorphosis,  by  which 
they  return  more  or  less  to  the  condition  of  ordinary  inorganic 
materials.  These  excrementitious  matters  are  themselves  decom- 
posed, after  being  expelled  from  the  body,  under  the  influence  of 
the  atmospheric  air  and  moisture ;  so  that  the  decomposition  and 
destruction  of  the  organic  substances  is  at  last  complete. 

It  will  be  seen,  consequently,  that  the  urine  has  a  character 
altogether  peculiar,  and  one  which  distinguishes  it  completely 
from  every  other  animal  fluid.  All  the  others  are  either  nutritive 
fluids,  like  the  blood  and  milk,  or  are  destined,  like  the  secretions 


GENERAL    CHARACTERS    OF    THE    URINE.  291 

generally,  to  take  some  direct  and  essential  part  in  the  vital  opera- 
tions. Many  of  them,  like  the  gastric  and  pancreatic  juices,  are 
reabsorbed  after  they  have  done  their  work,  and  again  enter  the 
current  of  the  circulation.  But  the  urine  is  merely  a  solution  of 
excrementitious  substances.  Its  materials  exist  beforehand  in  the 
circulation,  and  are  simply  drained  away  by  the  kidneys  from 
the  blood.  There  is  a  wide  difference,  accordingly,  between  the 
action  of  the  kidneys  and  that  of  the  true  glandular  organs,  in 
which  certain  new  and  peculiar  substances  are  produced  by  the 
action  of  the  glandular  tissue.  The  kidneys,  on  the  contrary,  do 
not  secrete  anything,  properly  speaking,  and  are  not,  therefore, 
glands.  In  their  mode  of  action,  so  far  as  regards  the  excretory 
function,  they  have  more  resemblance  to  the  lungs  than  to  any 
other  of  the  internal  organs.  But  this  resemblance  is  not  complete ; 
since  the  lungs  perform  a  double  function,  absorbing  oxygen  at  the 
same  time  that  they  exhale  carbonic  acid.  The  kidneys  alone  are 
purely  excretory  in  their  office.  The  urine  is  not  intended  to 
fulfil  any  function,  mechanical,  chemical,  or  otherwise ;  but  is  des- 
tined only  to  be  eliminated  and  expelled.  Since  it  possesses  so 
peculiar  and  important  a  character,  it  will  require  to  be  carefully 
studied  in  detail. 

The  urine  is  a  clear,  watery,  amber-colored  fluid,  with  a  distinct 
acid  reaction.  It  has,  while  still  warm,  a  peculiar  odor,  which  dis- 
appears more  or  less  completely  on  cooling,  and  returns  when  the 
urine  is  gently  heated.  The  ordinary  quantity  of  urine  discharged 
daily  by  a  healthy  adult  is  about  ^xxxv,  and  its  mean  specific 
gravity,  1024.  Both  its  total  quantity,  however,  and  its  mean 
specific  gravity  are  liable  to  vary  somewhat  from  day  to  day,  owing 
to  the  different  proportion  of  water  and  solid  ingredients  entering 
into  its  constitution.  Ordinarily  the  water  of  the  urine  is  more 
than  sufficient  to  hold  all  its  solid  matters  in  solution ;  and  its  pro- 
portion may  therefore  be  diminished  by  accidental  causes  without 
the  urine  becoming  turbid  by  the  formation  of  a  deposit.  Under 
such  circumstances,  it  merely  becomes  deeper  in  color,  and  of  a 
higher  specific  gravity.  Thus,  if  a  smaller  quantity  of  water  than 
usual  be  taken  into  the  system  with  the  drink,  or  if  the  fluid  ex- 
halations from  the  lungs  and  skin,  or  the  intestinal  discharges,  be 
increased,  a  smaller  quantity  of  water  will  necessarily  pass  off  by 
the  kidneys;  and  the  urine  will  be  diminished  in  quantity,  while  its 
specific  gravity  is  increased.     We  have  observed  the  urine  to  be 


292  EXCEETION. 

reduced  in  this  way  to  eighteen  or  twenty  ounces  per  day,  its  specific 
gravity  rising  at  the  same  time  to  1030.  On  the  other  hand,  if  the 
fluid  ingesta  be  unusually  abundant,  or  if  the  perspiration  be  dimi- 
nished, the  surplus  quantity  of  water  will  pass  oif  by  the  kidneys;  so 
that  the  amount  of  urine  in  twenty-four  hours  may  be  increased  to 
forty-five  or  forty-six  ounces,  and  its  specific  gravity  reduced  at 
the  same  time  to  1020  or  even  1017.  Under  these  conditions  the 
total  amount  of  solid  matter  discharged  daily  remains  about  the 
same.  The  changes  above  mentioned  depend  simply  upon  the 
fluctuating  quantity  of  water,  which  may  pass  off  by  the  kidneys 
in  larger  or  smaller  quantity,  according  to  accidental  circumstances. 
In  these  purely  normal  or  physiological  variations,  therefore,  the 
entire  quantity  of  the  urine  and  its  mean  specific  gravity  vary 
always  in  an  inverse  direction  with  each  other ;  the  former  increas- 
ing while  the  latter  diminishes,  and  vice  versa.  If,  however,  it 
should  be  found  that  both  the  quantity  and  specific  gravity  of  the 
urine  were  increased  or  diminished  at  the  same  time,  or  if  either 
one  were  increased  or  diminished  while  the  other  remained  station- 
ary, such  an  alteration  would  show  an  actual  change  in  the  total 
amount  of  solid  ingredients,  and  would  indicate  an  unnatural  and 
pathological  condition.  This  actually  takes  place  in  many  forms 
of  disease. 

The  amount  of  variation  in  the  quantity  of  water,  even,  may  be 
so  great  as  to  constitute  by  itself  a  pathological  condition.  Thus, 
in  hysterical  attacks  there  is  sometimes  a  very  abundant  flow  of 
limpid,  nearly  colorless  urine,  with  a  specific  gravity  not  over  1005 
or  1006.  On  the  other  hand,  in  the  onset  of  febrile  attacks,  the 
quantity  of  water  is  often  so  much  diminished  that  it  is  no  longer 
sufficient  to  retain  in  solution  all  the  solid  ingredients  of  the  urine, 
and  the  urate  of  soda  is  thrown  down,  after  cooling,  as  a  fine  red 
or  yellowish  sediment.  So  long,  however,  as  the  variation  is  con- 
fined within  strictly  physiological  limits,  all  the  solid  ingredients 
are  held  in  solution,  and  the  urine  remains  clear. 

There  is  also,  in  a  state  of  health,  a  diurnal  variation  of  the  urine, 
both  in  regard  to  its  specific  gravity  and  its  degree  of  acidity. 
The  urine  is  generally  discharged  from  the  bladder  five  or  six 
times  during  the  twenty-four  hours,  and  at  each  of  these  periods 
shows  more  or  less  variation  in  its  physical  characters.  We  have 
found  that  the  urine  which  collects  in  the  bladder  during  the  night, 
and  is  discharged  the  first  thing  in  the  morning,  is  usually  dense, 


DIURNAL    YARIATI0X3    OF    THE    URINE.  293 

highly  colored,  of  a  strongly  acid  reaction,  and  a  high  specific 
gravity.  That  passed  during  the  forenoon  is  pale,  and  of  a  low 
specific  gravit}'',  sometimes  not  more  than  1018  or  even  1015.  It 
is  at  the  same  time  neutral  or  slightly  alkaline  in  reaction.  Toward 
the  middle  of  the  day,  its  density  and  depth  of  color  increase,  and 
its  acidity  returns.  All  these  properties  become  more  strongl}- 
marked  during  the  afternoon  and  evening,  and  toward  night  the 
urine  is  again  deeply  colored  and  strongly  acid,  and  has  a  specific 
gravity  of  1028  or  1030. 

The  following  instances  will  serve  to  show  the  general  characters 
of  this  variation  : — 

Observation  First.     March  20 fh. 
Urine  of  1st  discharge,  acid,         sp.  gr.  1025. 
"     2d  "  alkaline,       "      1015. 

•'      3d  "  neutral,         "      1018. 

"      4th        "  acid,  "      1018. 

"      5th        "  acid,  "      1027. 

Observation  Second.     March  21st. 
Urine  of  1st  discharge,  acid,        sp.  gr.  1029. 
"      2d  "  neutral,       "       1022. 

"      3d  "  neutral,       "       1025. 

"      4th         "  acid,  "       1027. 

«      5th         "  acid,  "       1030. 

These  variations  do  not  always  follow  the  perfectly  regular 
course  manifested  in  the  above  instances,  since  they  are  somewhat 
liable,  as  we  have  already  mentioned,  to  temporary  modification 
from  accidental  causes  during  the  day  ;  but  their  general  tendency 
nearly  always  corresponds  with  that  given  above. 

It  is  evident,  therefore,  that  whenever  we  wish  to  test  the  specific 
gravity  and  acidity  of  the  urine  in  cases  of  disease,  it  will  not  be 
sufficient  to  examine  any  single  specimen  taken  at  random ;  but  all 
the  different  portions  discharged  during  the  day  should  be  collected 
and  examined  together.  Otherwise,  we  should  incur  the  risk  of 
regarding  as  a  permanently  morbid  symptom  what  might  be 
nothing  more  than  a  purely  accidental  and  temporary  variation. 

The  chemical  constitution  of  the  urine  as  it  is  discharged  from  the 
bladder,  according  to  the  analyses  of  Berzelius,  Lehmann,  Becquerel, 
and  others,  is  as  follows : — 


294  EXCKETION. 

Composition  of  the  Urine. 

Water 938.00 

Urea 30.00 

Creatine     ...........  1.25 

Creatinine  ..........  1.50 

Urate  of  soda  -^ 

"      potass        I 1.80 

"      ammonia  J 
Coloring  matter  and  •>  o^ 

Mucus  J 

Biphosphate  of  soda        -\ 
Phosphate  of  soda  j 

"  potass         I- 12.45 

"  magnesia   I 

"  lime  J 

Chlorides  of  sodium  and  potassium 7.80 

Sulphates  of  soda  and  potass     .......  6.90 

1000.00 

We  need  not  repeat  that  the  proportionate  quantity  of  these 
different  ingredients,  as  given  above,  is  not  absolute,  but  only 
approximative ;  and  that  they  vary,  from  time  to  time,  within  cer- 
tain physiological  limits,  like  the  ingredients  of  all  other  animal 
fluids. 

The  urea,  creatine,  creatinine,  and  urates  have  all  been  suffi- 
ciently described  above.  The  mucus  and  coloring  matter,  unlike 
the  other  ingredients  of  the  urine,  belong  to  the  class  of  organic 
substances  proper.  They  are  both  present,  as  may  be  seen  by  the 
analysis  quoted  above,  in  very  small  quantity.  The  coloring 
matter,  or  urosacine,  is  in  solution  in  a  natural  condition  of  the 
urine,  but  is  apt  to  be  entangled  by  any  accidental  deposits  which 
may  be  thrown  down,  and  more  particularly  by  those  consisting  of 
the  urates.  These  deposits,  from  being  often  strongly  colored  red 
or  pink  by  the  urosacine  thus  thrown  down  with  them,  are  known 
under  the  name  of  "  brick-dust"  sediments. 

The  mvcus  of  the  urine  comes  from  the  lining  membrane  of  the 
urinary  bladder.  When  first  discharged  it  is  not  visible,  owing  to 
its  being  uniformly  disseminated  through  the  urine  by  mechanical 
agitation ;  but  if  the  fluid  be  allowed  to  remain  at  rest  for  some 
hours  in  a  cylindrical  glass  vessel,  the  mucus  collects  at  the  bottom, 
and  may  then  be  seen  as  a  light  cottony  cloud,  interspersed  often 
with  minute  semi-opaque  points.  It  plays,  as  we  shall  hereafter 
see  a  very  important  part  in  the  subsequent  fermentation  and 
decomposition  of  the  urine. 


EEACTIONS    OF    THE    URINE.  295 

Biphosphate  of  soda  exists  in  the  urine  by  direct  solution,  since  it  is 
readily  soluble  in  water.  It  is  this  salt  which  gives  to  the  urine  its 
acid  reaction,  as  there  is  no  free  acid  present  in  the  recent  condition. 
It  is  probably  derived  from  the  neutral  phosphate  of  soda  in  the 
blood,  which  is  decomposed  by  the  uric  acid  at  the  time  of  its  for- 
mation ;  producing,  on  the  one  hand,  a  urate  of  soda,  and  converting 
a  part  of  the  neutral  phosphate  of  soda  into  the  acid  biphosphate. 

The  phosphates  of  lime  and  magnesia,  or  the  "  earthy  phosphates," 
as  they  are  called,  exist  in  the  urine  by  indirect  solution.  Though 
insoluble,  or  very  nearly  so,  in  pure  water,  they  are  held  in  solu- 
tion in  the  urine  by  the  acid  phosphate  of  soda,  above  described. 
They  are  derived  from  the  blood,  in  which  they  exist  in  considera- 
ble quantity.  When  the  urine  is  alkaline,  these  phosphates  are 
deposited  as  a  light  colored  precipitate,  and  thus  communicate  a 
turbid  appearance  to  the  fluid.  When  the  urine  is  neutral,  they 
may  still  be  held  in  solution,  to  some  extent,  by  the  chloride  of 
sodium,  which  has  the  property  of  dissolving  a  small  quantity  of 
phosphate  of  lime. 

The  remaining  ingredients,  phosphates  of  soda  and  potass,  sul- 
phates and  chlorides,  are  all  derived  from  the  blood,  and  are  held 
directly  in  solution  by  the  water  of  the  urine. 

The  urine,  constituted  by  the  above  ingredients,  forms,  as  we 
have  already  described,  a  clear  amber  colored  fluid,  with  a  reaction 
for  the  most  part  distinctly  acid,  sometimes  neutral,  and  occasion- 
ally slightly  alkaline.  In  its  healthy  condition  it  is  affected  by 
chemical  and  physical  reagents  in  the  following  manner. 

Boiling  the  urine  does  not  produce  any  visible  change,  provided 
its  reaction  be  acid.  If  it  be  neutral  or  alkaline,  and  if,  at  the  same 
time,  it  contain  a  larger  quantity  than  usual  of  the  earthy  phos- 
phates, it  will  become  turbid  on  boiling ;  since  these  salts  are  less 
soluble  at  a  high  than  at  a  low  temperature. 

The  addition  of  nitric,  or  other  mineral  acid,  produces  at  first  only 
a  slight  darkening  of  the  color,  owing  to  the  action  of  the  acid  upon 
the  organic  coloring  matter  of  the  urine.  If  the  mixture,  however, 
be  allowed  to  stand  for  some  time,  the  urates  of  soda,  potass,  &c., 
will  be  decomposed,  and  pure  uric  acid,  which  is  very  insoluble, 
will  be  deposited  in  a  crystalline  form  upon  the  sides  and  bottom 
of  the  glass  vessel.  The  crystals  of  uric  acid  have  most  frequently 
the  form  of  transparent  rhomboidal  plates,  or  oval  laminae  with 
pointed  extremities.  They  are  usually  tinged  of  a  yellowish  hue 
by  the  coloring  matter  of  the  urine  which  is  entangled  with  them 


296 


EXCEETION. 


Uric   Acid;  deposited  from  urine. 


at  the  time  of   their  deposit.     They  are  frequently  arranged  in 
radiated  clusters,  or  small  spheroidal  masses,  so  as  to  present  the 

appearance  of  minute  calcu- 
Fig-  115-  lous  concretions.  (Fig.  115.) 

The  crystals  vary  very  much 
in  size  and  regularity,  ac- 
cording to  the  time  occupied 
in  their  formation. 

If  a  free  alkali,  such  as 
potass  or  soda,  be  added  to 
the  urine,  so  as  to  neutralize 
its  acid  reaction,  it  becomes 
immediately  turbid  from  a 
deposit  of  the  earthy  phos- 
phates, which  are  insoluble 
in  alkaline  fluids. 

The  addition  of  nitrate  of 
baryta,  chloride  of  barium, 
or  subacetate  of  lead  to  healthy  urine,  produces  a  dense  precipi- 
tate, owing  to  the  presence  of  the  alkaline  sulphates. 

Nitrate  of  silver  produces  a  precipitate  with  the  chlorides  of 
sodium  and  potassium. 

Subacetate  of  lead  and  nitrate  of  silver  precipitate  also  the  or- 
ganic substances,  mucus  and  coloring  matter,  present  in  the  urine. 
All  the  above  reactions,  it  will  be  seen,  are  owing  to  the  presence 
of  the  natural  ingredients  of  the  urine,  and  do  not,  therefore,  indi- 
cate any  abnormal  condition  of  the  excretion. 

Besides  the  properties  mentioned  above,  the  urine  has  several 
others  which  are  of  some  importance,  and  which  have  not  been 
usually  noticed  in  previous  descriptions.  It  contains,  among  other 
ingredients,  certain  organic  substances  which  have  the  power  of  in- 
terfering with  the  mutual  reaction  of  starch  and  iodine,  and  even  of 
decomposing  the  iodide  of  starch,  after  it  has  once  been  formed. 
This  peculiar  action  of  the  urine  was  first  noticed  and  described 
by  us  in  1856.^  If  5j  of  iodine  water  be  mixed  with  a  solution 
of  starch,  it  strikes  an  opaque  blue  color ;  but  if  5j  of  fresh  urine 
be  afterward  added  to  the  mixture,  the  color  is  entirely  destroyed 
at  the  end  of  four  or  five  seconds.  If  fresh  urine  again  be  mixed 
with  four  or  five  times  its  volume  of  iodine  water,  and  starch  be 


'  American  Journal  Med.  Sci.,  April,  1856. 


ACCIDENTAL    INGEEDIENTS    OF    THE    UKINE.  297 

subsequently  added,  no  union  takes  place  between  the  starch  and 
iodine,  and  no  blue  color  is  produced.  In  these  instances,  the  iodine 
unites  with  the  animal  matters  of  the  urine  in  preference  to  com- 
bining with  the  starch,  and  is  consequently  prevented  from  striking 
its  ordinary  blue  color  with  the  latter.  This  interference  occurs 
whether  the  urine  be  acid  or  alkaline  in  reaction.  In  all  cases  in 
which  iodine  exists  in  the  urine,  as  for  example  where  it  has  been 
administered  as  a  medicine,  it  is  under  the  form  of  an  organic  com- 
bination ;  and  in  order  to  detect  its  presence  by  means  of  starch,  a 
few  drops  of  nitric  acid  must  be  added  at  the  same  time,  so  as  to 
destroy  the  organic  matters,  after  which  the  blue  color  immediately 
appears,  if  iodine  be  present.  This  reaction  with  starch  and  iodine 
belongs  also,  to  some  extent,  to  most  of  the  other  animal  fluids,  as 
the  saliva,  gastric  and  pancreatic  juices,  serum  of  the  blood,  &c. ; 
but  it  is  most  strongly  marked  in  the  urine. 

Another  remarkable  property  of  the  urine,  also  dependent  on  its 
organic  ingredients,  is  that  of  interfering  with  Trommer's  test  for 
grape  sugar.  If  clarified  honey  be  mixed  with  fresh  urine,  and  sul- 
phate of  copper  with  an  excess  of  potass  be  afterward  added,  the 
mixture  takes  a  dingy,  grayish-blue  color.  On  boiling,  the  color 
turns  yellowisb  or  yellowish-brown,  but  the  suboxide  of  copper  is 
not  deposited.  In  order  to  remove  the  organic  matter  and  detect 
the  sugar,  the  urine  must  be  first  treated  with  an  excess  of  animal 
charcoal  and  filtered.  By  this  means  the  organic  substances  are 
retained  upon  the  filter,  while  the  sugar  passes  through  in  solution, 
and  may  then  be  detected  as  usual  by  Trommer's  test. 

Accidental  Ingeedients  of  the  Ueine. — Since  the  urine,  in 
its  natural  state,  consists  of  materials  which  are  already  prepared  in 
the  blood,  and  which  merely  pass  out  through  the  kidneys  by  a 
kind  of  filtration,  it  is  not  surprising  that  most  medicinal  and 
poisonous  substances,  introduced  into  the  circulation,  should  be 
expelled  from  the  body  by  the  same  channel.  Those  substances 
which  tend  to  unite  strongly  with  the  animal  matters,  and  to  form 
with  them  insoluble  compounds,  such  as  the  preparations  of  iron, 
lead,  silver,  arsenic,  mercury,  &c.,  are  least  liable  to  appear  in  the 
urine.  They  may  occasionally  be  detected  in  this  fluid  when  they 
have  been  given  in  large  doses,  but  when  administered  in  moderate 
quantity  are  not  usually  to  be  found  there.  Most  other  substances, 
however,  accidentally  present  in  the  circulation,  pass  off  readily  by 


298  EXCRETION. 

the  kidneys,  either  in  their  original  form,  or  after  undergoing  cer- 
tain chemical  modifications. 

The  salts  of  the  organic  acids,  such  as  lactates^  acetates,  malates, 
&G.,  of  soda  and  potass,  when  introduced  into  the  circulation,  are 
replaced  by  the  carbonates  of  the  same  bases,  and  appear  under 
that  form  in  the  urine.  The  urine  accordingly  becomes  alkaline 
from  the  presence  of  the  carbonates,  whenever  the  above  salts  have 
been  taken  in  large  quantity,  or  after  the  ingestion  of  fruits  and 
vegetables  which  contain  them.  We  have  already  spoken  (Chap.  II.) 
of  the  experiments  of  Lehmann,  in  which  he  found  the  urine  exhi- 
biting an  alkaline  reaction,  a  very  few  minutes  after  the  adminis- 
tration of  lactates  and  acetates.  In  one  instance,  by  experimenting 
upon  a  person  with  congenital  extroversion  of  the  bladder,  in  whom 
the  orifices  of  the  ureters  were  exposed,^  he  found  that  the  urine 
became  alkaline  in  the  course  of  seven  minutes  after  the  ingestion 
of  half  an  ounce  of  acetate  of  potass. 

The  2^ure  alkalies  and  their  carbonates,  according  to  the  same  ob- 
server, produce  a  similar  effect.  Bicarbonate  of  potass,  for  example, 
administered  in  doses  of  two  or  three  drachms,  causes  the  urine 
to  become  neutral  in  from  thirty  to  forty-five  minutes,  and  alkaline 
in  the  course  of  an  hour.  It  is  in  this  way  that  certain  "anti-cal- 
culous"  or  "  anti-lithic"  nostrums  operate,  when  given  with  a  view 
of  dissolving  concretions  in  the  bladder.  These  remedies,  which 
are  usually  strongly  alkaline,  pass  into  the  urine,  and  by  giving  it 
an  alkaline  reaction,  produce  a  precipitation  of  the  earthy  phos- 
phates. Such  a  precipitate,  however,  so  far  from  indicating  the 
successful  disintegration  and  discharge  of  the  calculus,  can  only 
tend  to  increase  its  size  by  additional  deposits. 

Ferrocyanide  of  potassium,  when  introduced  into  the  circulation, 
appears  readily  in  the  urine.  Bernard^  observed  that  a  solution  of 
this  salt,  after  being  injected  into  the  duct  of  the  submaxillary 
gland,  could  be  detected  in  the  urine  at  the  end  of  twenty  minutes. 

Iodine^  in  all  its  combinations,  passes  out  by  the  same  channel. 
We  have  found  that  after  the  administration  of  half  a  drachm  of 
the  syrup  of  iodide  of  iron,  iodine  appears  in  the  urine  at  the  end 
of  thirty  minutes,  and  continues  to  be  present  for  nearly  twenty- 
four  hours.  In  the  case  of  two  patients  who  had  been  taking  iodide 
of  potassium  freel}--,  one  of  them  for  two  months,  the  other  for  six 

'  Physiological  Chemistry,  vol.  ii.  p.  133. 

2  Leqons  de  Physiologie  Experimentale,  1855,  vol.  ii.  p.  111. 


ACCIDENTAL    INGREDIENTS    OF    THE    URINE.  299 

weeks,  the  urine  still  contained  iodine  at  the  end  of  three  days 
after  the  suspension  of  the  medicine.  In  three  days  and  a  half, 
however,  it  was  no  longer  to  be  detected.  Iodine  appears  also,  after 
being  introduced  into  the  circulation,  both  in  the  saliva  and  the 
perspiration. 

Quinine^  when  taken  as  a  remedy,  has  also  been  detected  in  the 
urine.  Ether  passes  out  of  the  circulation  in  the  same  way.  We 
have  observed  the  odor  of  this  substance  very  perceptible  in  the 
urine,  after  it  had  been  inhaled  for  the  purpose  of  producing  anees- 
thesia.  The  bile-pigment  passes  into  the  urine  in  great  abundance 
in  some  cases  of  jaundice,  so  that  the  urine  may  have  a  deep  yellow 
or  yellowish  brown  tinge,  and  may  even  stain  linen  clothes,  with 
which  it  comes  in  contact,  of  a  similar  color.  The  saline  biliary 
substances,  viz.,  glyko-cholate  and  tauro-cholate  of  soda,  have  occa- 
sionally, according  to  Lehmann,  been  also  found  in  the  urine.  In 
these  instances  the  biliary  matters  are  reabsorbed  from  the  hepatic 
ducts,  and  afterward  conveyed  by  the  blood  to  the  kidneys. 

Sugar. — When  sugar  exists  in  unnatural  quantity  in  the  blood,  it 
passes  out  with  the  urine.  We  have  repeatedly  found  that  if  sugar 
be  artificially  introduced  into  the  circulation  in  rabbits,  or  injected 
into  the  subcutaneous  areolar  tissue  so  as  to  be  absorbed  by  the 
blood,  it  is  soon  discharged  by  the  kidneys.  It  has  been  shown  by 
Bernard*  that  the  rapidity  with  which  this  substance  appears  in  the 
urine  under  these  circumstances  varies  with  the  quantity  injected 
and  the  kind  of  sugar  used  for  the  experiment.  If  a  solution  of  15 
grains  of  glucose  be  injected  into  the  areolar  tissue  of  a  rabbit 
weighing  a  little  over  two  pounds,  it  is  entirely  destroyed  in  the  cir- 
culation, and  does  not  pass  out  with  the  urine.  A  dose  of  23  grains, 
however,  injected  in  the  same  way,  appears  in  the  urine  at  the  end 
of  two  hours,  30  grains  in  an  hour  and  a  half,  38  grains  in  an  hour, 
and  188  grains  in  fifteen  minutes.  Again,  the  kind  of  sugar  used 
causes  a  difference  in  this  respect.  For  while  15  grains  of  glucose 
may  be  injected  without  passing  out  by  the  kidneys,  7J  grains  of 
cane  sugar,  introduced  in  the  same  way,  fail  to  be  completely  de- 
stroyed in  the  circulation,  and  may  be  detected  in  the  urine.  In 
certain  forms  of  disease  (diabetes),  where  sugar  accumulates  in 
the  blood,  it  is  eliminated  by  the  same  channel ;  and  a  saccharine 
condition  of  the  urine,  accompanied  by  an  increase  in  its  quantity 

'  Legons  de  Phys.  Exp.,  1855,  vol.  i.  p.  214  et  seq. 


300  EXCEETION. 

and  specific  gravity,  constitutes  the  most  cbaracteristic  feature  of 
the  disease. 

Finally,  albumen  sometimes  shows  itself  in  the  urine  in  conse- 
quence of  various  morbid  conditions.  Most  acute  inflammations 
of  the  internal  organs,  as  pneumonia,  pleurisy,  &c.,  are  liable  to  be 
accompanied,  at  their  outset,  by  a  congestion  of  the  kidneys,  which 
produces  a  temporary  exudation  of  the  albuminous  elements  of  the 
blood.  Albumen  has  been  found  in  the  urine,  according  to  Simon, 
Becquerel,  and  others,  in  pericarditis,  pneumonia,  pleurisy,  bron- 
chitis, hepatitis,  inflammation  of  the  brain,  peritonitis,  metritis,  &c. 
"We  have  observed  it,  as  a  temporary  condition,  in  pneumonia  and 
after  amputation  of  the  thigh.  Albuminous  urine  also  occurs  fre- 
quently in  pregnant  women,  and  in  those  affected  with  abdominal 
tumors,  where  the  pressure  upon  the  renal  veins  is  sufficient  to 
produce  passive  congestion  of  the  kidneys.  When  the  renal  con- 
gestion is  spontaneous  in  its  origin,  and  goes  on  to  produce  actual 
degeneration  of  the  tissue  of  the  kidneys,  as  in  Bright's  disease, 
the  same  symptom  occurs,  and  remains  as  a  permanent  condition. 
In  all  such  instances,  however,  as  the  above,  where  foreign  ingre- 
dients  exist  in  the  urine,  these  substances  do  not  originate  in  the 
kidneys  themselves,  but  are  derived  from  the  blood,  in  the  same 
manner  as  the  natural  ingredients  of  the  excretion. 

Changes  in  the  Urine  during  Decomposition, — When  the 
urine  is  allowed  to  remain  exposed,  after  its  discharge,  at  ordinary 
temperatures,  it  becomes  decomposed,  after  a  time,  like  any  other 
animal  fluid ;  and  this  decomposition  is  characterized  by  certain 
changes  which  take  place  in  a  regular  order  of  succession,  as  fol- 
lows:— 

After  a  few  hours  of  repose,  the  mucus  of  the  urine,  as  we  have 
mentioned  above,  collects  near  the  bottom  of  the  vessel  as  a  light, 
nearly  transparent,  cloudy  layer.  This  mucus,  being  an  organic  sub- 
stance, is  liable  to  putrefaction ;  and  if  the  temperature  to  which  it  is 
exposed  be  between  60°  and  100°  F.,  it  soon  becomes  altered  and 
communicates  these  alterations,  more  or  less  rapidly,  to  the  superna- 
tant fluid.  The  first  of  these  changes  is  called  the  acid  fermentation 
of  the  urine.  It  consists  in  the  production  of  a  free  acid,  usually 
lactic  acid,  from  some  of  the  undetermined  animal  matters  con- 
tained in  the  excretion.  This  fermentation  takes  place  very  early ; 
within  the  first  twelve,  twenty-four,  or  forty-eight  hours,  according 
to  the  elevation  of  the  surrounding  temperature.     Perfectly  fresh 


ACID    FERMENTATION    OF    THE    URINE.  301 

urine,  as  we  have  already  stated,  contains  no  free  acid,  its  acid 
reaction  to  test  paper  being  dependent  entirely  on  the  presence  of 
biphosphate  of  soda.  Lactic  acid  nevertheless  has  been  so  fre- 
quently found  in  nearly  fresh  urine  as  to  lead  some  eminent 
chemists  (Berzelius,  Lehmann)  to  regard  it  as  a  natural  constituent 
of  the  excretion.  It  has  been  subsequently  found,  however,  that 
urine,  though  entirely  free  from  lactic  when  first  passed,  may  fre- 
quently present  traces  of  this  substance  after  some  hours'  exposure 
to  the  air.  The  lactic  acid  is  undoubtedly  formed,  in  these  cases, 
by  the  decomposition  of  some  animal  substance  contained  in  the 
urine.  Its  production  in  this  way,  though  not  constant,  seems  to 
be  sufficiently  frequent  to  be  regarded  as  a  normal  process. 

In  consequence  of  the  presence  of  this  acid,  the  urates  are  par- 
tially decomposed ;  and  a  crystalline  deposit  of  free  uric  acid  slowly 
takes  place,  in  the  same  manner  as  if  a  little  nitric  or  muriatic  acid 
had  been  artificially  mixed  with  the  urine.  It  is  for  this  reason 
that  urine  which  is  abundant  in  the  urates  frequently  shows  a  de- 
posit of  crystallized  uric  acid  some  hours  after  it  has  been  passed, 
though  it  may  have  been  perfectly  free  from  deposit  at  the  time 
of  its  emission. 

During  the  period  of  the  "acid  fermentation,"  there  is  reason  to 
believe  that  oxalic  acid  is  also  sometimes  produced  in  a  similar 
manner  with  the  lactic.  It  is  very  certain  that  the  deposit  of  oxa- 
late of  lime,  far  from  being  a  dangerous  or  even  morbid  symptom, 
as  it  was  at  one  time  regarded,  is  frequently  present  in  perfectly 
normal  urine  after  a  day  or  two  of  exposure  to  the  atmosphere. 
We  have  often  observed  it,  under  these  circumstances,  when  no 
morbid  symptom  could  be  detected  in  connection  with  either  the 
kidneys  or  any  other  bodily  organ.  Now,  whenever  oxalic  acid 
is  formed  in  the  urine,  it  must  necessarily  be  deposited  under 
the  form  of  oxalate  of  lime ;  since  this  salt  is  entirely  insoluble 
both  in  water  and  in  the  urine,  even  when  heated  to  the  boiling 
point.  It  is  difficult  to  understand,  therefore,  when  oxalate  of 
lime  is^ found  as  a  deposit  in  the  urine,  how  it  can  previously  have 
been  held  in  solution.  Its  oxalic  acid  is  in  all  probability  gradually 
formed,  as  we  have  said,  in  the  urine  itself;  uniting,  as  fast  as  it  is 
produced,  with  the  lime  previously  in  solution,  and  thus  appearing 
as  a  crystalline  deposit  of  oxalate  of  lime.  It  is  much  more  probable 
that  this  is  the  true  explanation,  since,  in  the  cases  to  which  we 
allude,  the  crystals  of  oxalate  of  lime  grow,  as  it  were,  in  the  cloud 
of  mucus  which  collects  at  the  bottom  of  the  vessel,  while  the 


302 


EXCRETION. 


Oxalate  op  Lime;  deposited  from  healthy  urine, 
during  the  acid  fevmentatiou. 


supernatant  fluid  remains  clear.     These  crystals  are  of  minute  size, 

transparent,    and    colorless, 
^'S-  ^^^-  and  have  tlie  form  of  regular 

octohedra,  or  double  quad- 
rangular   pyramids,   united 
base  to  base.  (Fig.  116.)  They 
make  their  appearance  usu- 
ally about   the   commence- 
ment of  the  second  day,  the 
urine  at  the  same  time  con- 
tinuing clear  and  retaining 
its  acid  reaction.   This  depo- 
sit is  of  frequent  occurrence 
when  no  substance  contain- 
ing oxalic  acid  or  oxalates 
has  been  taken  with  the  food. 
At  the  end  of  some  days 
the  changes  above  described 
come  to  an  end,  and  are  succeeded  by  a  different  process  known  as 
the  alkaline  fermentation.     This  consists  essentially  in  the  decompo- 
sition or  metamorphosis  of  the  urea  into  carbonate  of  ammonia. 
As  the  alteration  of  the  mucus  advances,  it  loses  the  power  of  pro- 
ducing lactic  and  oxalic  acids,  and  becomes  a  ferment  capable  of 
acting  by  catalysis  upon  the  urea,  and  of  exciting  its  decomposition 
as  above.     We  have  already  mentioned  that  urea  may  be  converted 
into  carbonate  of  ammonia  by  prolonged  boiling  or  by  contact 
with  decomposing  animal  substances.     In  this  conversion,  the  urea 
unites  with  the  elements  of  two  equivalents  of  water ;  and  conse- 
quently it  is  not  susceptible  of  the  transformation  when  in  a  dry 
state,  but  only  when  in  solution  or  supplied  with  a  sufficient  quan- 
tity of  moisture.     The  presence  of  mucus,  in  a  state  of  incipient 
decomposition,  is  also  necessary,  to  act  the  part  of  a  catalytic  body. 
Consequently  if  the  urine  when  first  discharged  be  passed  through 
a  succession  of  close  filters,  so  as  to  separate  and  retain  its  mucus,  it 
may  be  afterward  kept,  for  an  almost  indefinite  time,  without  altera- 
tion.    But  under  ordinary  circumstances,  the  mucus,  as  soon  as  its 
putrefaction  has  commenced,  excites  the  decomposition  of  the  urea, 
and  carbonate  of  ammonia  begins  to  be  developed. 

The  first  portions  of  the  ammoniacal  salt  thus  produced  begin  to 
neutralize  the  biphosphate  of  soda,  so  that  the  acid  reaction  of  the 
urine  diminishes  in  intensity.     This   reaction  gradually  becomes 


ALKALINE    FERMENTATION    OF    THE    URINE.  303 

weaker  and  weaker,  as  the  fermentation  proceeds,  until  it  at  last 
disappears  altogether,  and  the  urine  becomes  neutral.  The  produc- 
tion of  carbonate  of  ammonia  still  continuing,  the  reaction  of  the 
fluid  then  becomes  alkaline,  and  its  alkalescence  grows  more  strongly 
pronounced  with  the  constant  accumulation  of  the  ammoniacal  salt. 

The  rapidity  with  which  this  alteration  proceeds  depends  on  the 
character  of  the  urine,  the  quantity  and  quality  of  the  mucus  which 
it  contains,  and  the  elevation  of  the  surrounding  temperature.  The 
urine  passed  early  in  the  forenoon,  which  is  often  neutral  at  the 
time  of  its  discharge,  will  of  course  become  alkaline  more  readily 
than  that  which  has  at  first  a  strongly  acid  reaction.  In  the  summer, 
urine  will  become  alkaline,  if  freely  exposed,  on  the  third,  fourth, 
or  fifth  day ;  while  in  the  winter,  a  specimen  kept  in  a  cool  place 
may  still  be  neutral  at  the  end  of  fifteen  days.  In  cases  of  paralysis 
of  the  bladder,  on  the  other  hand,  accompanied  with  cystitis,  where 
the  mucus  is  increased  in  quantity  and  altered  in  quality,  and  the 
urine  retained  in  the  bladder  for  ten  or  twelve  hours  at  the  tem- 
perature of  the  body,  the  change  may  go  on  much  more  rapidly,  so 
that  the  urine  may  be  distinctly  alkaline  and  ammoniacal  at  the 
time  of  its  discharge.  In  these  cases,  however,  it  is  really  acid 
when  first  secreted  by  the  kidneys,  and  becomes  alkaline  while 
retained  in  the  interior  of  the  bladder. 

The  first  effect  of  the  alkaline  condition  of  the  urine,  thus  pro- 
duced, is  the  precipitation  of  the  earthy  phosphates.  These  salts, 
being  insoluble  in  neutral  and  alkaline  fluids,  begin  to  precipitate  as 
soon  as  the  natural  acid  reaction  of  the  urine  has  fairly  disappeared, 
and  thus  produce  in  the  fluid  a  whitish  turbidity.  This  precipitate 
slowly  settles  upon  the  sides  and  bottom  of  the  vessel,  or  is  partly 
entangled  with  certain  animal  matters  which  rise  to  the  surface  and 
form  a  thin,  opaline  scum  upon  the  urine.  There  are  no  crystals 
to  be  seen  at  this  time,  but  the  deposit  is  entirely  amorphous  and 
granular  in  character. 

The  next  change  consists  in  the  production  of  two  new  double 
salts  by  the  action  of  carbonate  of  ammonia  on  the  phosphates  of 
soda  and  magnesia.  One  of  these  is  the  "  triple  phosphate,"  phos- 
phate of  magnesia  and  ammonia  (2MgO,NHp,P05-f  2H0).  The 
other  is  the  phosphate  of  soda  and  ammonia  (NaO,NIip,IIO,POj-f 
8H0).  The  phosphate  of  magnesia  and  ammonia  is  formed  from 
the  phosphate  of  magnesia  in  the  urine  (SMgOjPO^+THO)  by  the 
replacement  of  one  equivalent  of  magnesia  by  one  of  ammonia. 
The  crystals  of  this  salt  are  very  elegant  and  characteristic.     They 


304 


EXCRETION. 


Fig.  117. 


Phosphate  of  Magnesia  and  Ammonia; 
deposited  from  healthy  urine,  during  alkaline  fermen- 
tation. 


show  themselves  throughout  all  parts  of  the  mixture ;  growing  gra- 
dually in  the  mucus  at  the  bottom,  adhering  to  the  sides  of  the 

glass,  and  scattered  abund- 
antly over  the  film  which  col- 
lects, as  we  have  mentioned, 
upon  the  surface.  By  their 
refractive  power,  they  give 
to  this  film  a  peculiar  glisten- 
ing or  iridescent  appearance, 
which  is  nearly  always  visi- 
ble at  the  end  of  six  or  seven 
days.  The  crystals  are  per- 
fectly colorless  and  transpa- 
rent, and  have  the  form  of 
triangular  prisms,  generally 
with  bevelled  extremities. 
(Fig.  117.)  Frequentlj'-,  also, 
their  edges  and  angles  are 
replaced  by  secondary  facets. 
They  are  insoluble  in  alkalies,  but  are  easily  dissolved  by  acids, 
even  in  a  very  dilute  form.  At  first  they  are  of  minute  size,  but 
gradually  increase,  so  that  after  seven  or  eight  days  they  may 
become  visible  to  the  naked  eye. 

The  phosphate  of  soda  and  ammonia  is  formed,  in  a  similar  man- 
ner to  the  above,  by  the  union  of  ammonia  with  the  phosphate  of 
soda  previously  existing  in  the  urine.  Its  crystals  resemble  very 
much  those  just  described,  except  that  their  prisms  are  of  a  quad- 
rangular form,  or  some  figure  derived  from  it.  They  are  inter- 
mingled with  the  preceding  in  the  putrefying  urine,  and  are  affected 
in  the  same  way  by  chemical  reagents. 

As  the  putrefaction  of  the  urine  continues,  the  carbonate  of  am- 
monia which  is  produced,  after  saturating  all  the  other  ingredients 
with  which  it  is  capable  of  entering  into  combination,  begins  to 
be  given  off  in  a  free  form.  The  urine  then  acquires  a  strong 
ammoniacal  odor;  and  a  piece  of  moistened  test  paper,  held  a  little 
above  its  surface,  will  have  its  color  immediately  turned  by  the 
alkaline  gas  escaping  from  the  fluid.  This  is  the  source  of  the 
ammoniacal  vapor  which  is  so  freely  given  off  from  stables  and  from 
dung  heaps,  or  wherever  urine  is  allowed  to  remain  and  decompose. 
This  process  continues  until  all  the  urea  has  been  destroyed,  and 
until  the  products  of  its  decomposition  have  either  united  with 
other  substances,  or  have  finally  escaped  in  a  gaseous  form. 


SECTION  11. 
NERVOUS    SYSTEM. 


CHAPTER   I. 

GENERAL   STRUCTURE    AND   FUNCTIONS   OF   THE 
NERVOUS   SYSTEM 

Iisr  entering  upon  the  study  of  the  nervous  system,  we  commence, 
the  examination  of  an  entirely  different  order  of  phenomena  from 
those  which  have  thus  far  engaged  our  attention.  Hitherto  we 
have  studied  the  physical  and  chemical  actions  taking  place  in  the 
body  and  constituting  together  the  process  of  nutrition.  We  have 
seen  how  the  lungs  absorb  and  exhale  different  gases;  how  the 
stomach  dissolves  the  food  introduced  into  it,  and  how  the  tissues 
produce  and  destroy  different  substances  by  virtue  of  the  varied 
transformations  which  take  place  in  their  interior.  In  all  these 
instances,  we  have  found  each  organ  and  each  tissue  possessing 
certain  properties  and  performing  certain  functions,  of  a  physical 
or  chemical  nature,  which  belong  exclusively  to  it,  and  are  charac- 
teristic of  its  action. 

The  functions  of  the  nervous  system,  however,  are  neither  phy- 
sical nor  chemical  in  their  nature.  They  do  not  correspond,  in 
their  mode  of  operation,  with  any  known  phenomena  belonging  to 
these  two  orders.  The  nervous  system,  on  the  contrary,  acts  only 
upon  other  organs,  in  some  unexplained  manner,  so  as  to  excite  or 
modify  the  functions  peculiar  to  them.  It  is  not  therefore  an  appa- 
ratus which  acts  for  itself,  but  is  intended  entirely  for  the  purpose 
of  influencing,  in  an  indirect  manner,  the  action  of  other  organs. 
Its  object  is  to  connect  and  associate  the  functions  of  different  parts 
of  the  body,  and  to  cause  them  to  act  in  harmony  with  each  other. 
20 


306  GENERAL    STRUCTURE    AND    FUNCTIONS 

This  object  may  be  more  fully  exemplified  as  follows: — 
Each  organ  and  tissue  in  the  body  has  certain  properties  peculiar 
to  it,  which  may  be  called  into  activity  by  the  operation  of  a  stimu- 
lus or  exciting  cause.  This  capacity,  which  all  the  organs  possess, 
of  reacting  under  the  influence  of  a  stimulus,  is  called  their  excita- 
bility, or  irntability.  "We  have  often  had  occasion  to  notice  this  pro- 
perty of  irritability,  in  experiments  related  in  the  foregoing  pages. 
We  have  seen,  for  example,  that  if  the  heart  of  a  frog,  after  being 
removed  from  the  body,  be  touched  with  the  point  of  a  needle,  it 
immediately  contracts,  and  repeats  the  movement  of  an  ordinary 
pulsation.  If  the  leg  of  a  frog  be  separated  from  the  thigh,  its 
integument  removed,  and  the  poles  of  a  galvanic  battery  brought 
in  contact  with  the  exposed  surface  of  the  muscles,  a  violent  con- 
traction takes  place  every  time  the  electric  circuit  is  completed. 
In  this  instance,  the  stimulus  to  the  muscles  is  supplied  by  the 
electric  discharge,  as,  in  the  case  of  the  heart  above  mentioned,  it  is 
supplied  by  the  contact  of  the  steel  needle ;  and  in  both,  a  muscu- 
lar contraction  is  the  immediate  consequence.  If  we  introduce  a 
metallic  catheter  into  the  empty  stomach  of  a  dog  through  a  gastric 
fistula,  and  gently  irritate  with  it  the  mucous  membrane,  a  secretion 
of  gastric  juice  at  once  begins  to  take  place ;  and  if  food  be  intro- 
duced the  fluid  is  poured  out  in  still  greater  abundance.  We  know 
also  that  if  the  integument  be  exposed  to  contact  with  a  heated 
body,  or  to  friction  with  an  irritating  liquid,  an  excitement  of  the 
circulation  is  at  once  produced,  which  again  passes  away  after  the 
removal  of  the  irritating  cause. 

In  all  these  instances  we  find  that  the  organ  which  is  called  into 
activity  is  excited  by  the  direct  application  of  some  stimulus  to  its 
own  tissues.  But  this  is  not  usually  the  manner  in  which  the  dif- 
ferent functions  are  excited  during  life.  The  stimulus  which  calls 
into  action  the  organs  of  the  living  body  is  usually  not  direct,  but 
indirect  in  its  operation.  Generally  speaking,  the  organs  which  are 
situated  in  distant  parts  are  connected  with  each  other  by  such  a 
sympathy,  that  the  activity  of  one  is  influenced  by  the  condition  of 
the  others.  The  muscles,  for  example,  are  almost  never  called  into 
action  by  an  external  stimulus  operating  directly  upon  their  own 
fibres,  but  by  one  which  is  applied  to  some  other  organ,  either  adja- 
cent or  remote.  Thus  the  peristaltic  action  of  the  muscular  coat  of 
the  intestine  commences  when  the  food  is  brought  in  contact  with 
its  mucous  membrane.  The  lachrymal  gland  is  excited  to  an  in- 
creased activity  by  anything  which  causes  irritation  of  the  conjunc- 


OF    THE    NERVOUS    SYSTEM.  307 

tiva.  In  all  such  instances,  the  physiological  connection  between 
two  different  organs  is  established  through  the  medium  of  the 
nervous  system. 

The  function  of  the  nervous  system  may  therefore  be  defined,  in 
the  simplest  terms,  as  follows :  It  is  intended  to  associate  the  different 
parts  of  the  body  in  such  a  manner^  that  an  action  may  be  excited  in  one 
organ  by  means  of  a  stimulus  applied  to  another. 

The  instances  of  this  mode  of  action  are  exceedingly  numerous. 
Thus,  the  light  which  falls  upon  the  retina  produces  a  contraction 
of  the  pupil.  The  presence  of  food  in  the  stomach  causes  the  gall- 
bladder to  discharge  its  contents  into  the  duodenum.  The  expul- 
sive efforts  of  coughing  are  excited  by  a  foreign  body  entangled  in 
the  glottis. 

It  is  easy  to  understand  the  great  importance  of  this  function, 
particularly  in  the  higher  animals  and  in  man,  whose  organization 
is  an  exceedingly  complicated  one.  For  the  different  organs  of  the 
body,  in  order  to  preserve  the  integrity  of  the  whole  frame,  must 
not  only  act  and  perform  their  functions,  but  they  must  act  in  har- 
mony with  each  other,  and  at  the  right  time,  and  in  the  right  direc- 
tion. The  functions  of  circulation,  of  respiration,  and  of  digestion, 
are  so  mutually  dependent,  that  if  their  actions  do  not  take  place 
harmoniously,  and  in  proper  order,  a  serious  disturbance  must 
inevitably  follow.  When  the  muscular  system  is  excited  by  unu- 
sual exertion,  the  circulation  is  also  quickened.  The  blood  arrives 
more  rapidly  at  the  heart,  and  is  sent  in  greater  quantity  to  the 
lungs.  If  the  movements  of  respiration  were  not  accelerated,  at 
the  same  time,  through  the  connections  of  the  nervous  system,  there 
would  immediately  follow  deficiency  of  aeration,  pulmonary  conges- 
tion, and  accumulation  of  blood  on  the  right  side  of  the  heart.  If 
the  iris  were  not  stimulated  to  contract  by  the  influence  of  the  light 
falling  on  the  retina,  the  delicate  expansion  of  the  optic  nerve 
would  be  dazzled  by  any  unusual  brilliancy,  and  vision  would  be 
obscured  or  confused.  In  all  the  higher  animals,  therefore,  where 
the  different  functions  of  the  body  are  performed  by  distinct  organs, 
situated  in  different  parts  of  the  frame,  it  is  necessary  that  their 
action  should  be  thus  regulated  and  harmonized  by  the  operation 
of  the  nervous  system. 

The  manner  in  which  this  is  accomplished  is  as  follows: — 
The  nervous  system,  however  simple  or  however  complicated  it 
may  be,  consists  always  of  two  different  kinds  of  tissue,  which  are 


308  GENERAL    STRUCTURE    AND    FUNCTIONS 

distinguished  from  each  other  by  their  color,  their  structure,  and 
their  mode  of  action.  One  of  these  is  known  as  the  white  substance, 
or  i\iQ  fibrous  tissue.  It  constitutes  the  whole  of  the  substance  of  the 
nervous  trunks  and  branches,  and  is  found  in  large  quantity  on  the 
exterior  ot  the  spinal  cord,  and  in  the  central  parts  of  the  brain 
and  cerebellum.  In  the  latter  situations,  it  is  of  a  soft  consistency, 
like  curdled  cream,  and  of  a  uniform,  opaque  white  color.  In 
the  trunks  and  branches  of  the  nerves  it  has  the  same  opaque 
white  color,  but  is  at  the  same  time  of  a  firmer  consistency,  owing 
to  its  being  mingled  with  condensed  areolar  tissue.  Examined  by 
the  microscope,  the  white  substance  is  seen  to  be  composed  every- 
where of  minute  fibres  or  filaments,  the  "ultimate  nervous  fila- 
ments," running  in  a  direction  very  nearly  parallel  with  each  other. 
These  filaments  are  cylindrical  in  shape,  and  vary  considerably  in 
size.  Those  which  are  met  with  in  the  spinal  cord  and  the  brain 
are  the  smallest,  and  have  an  average  diameter  of  yo^oo  of  an 
inch.  In  the  trunks  and  branches  of  the  nerves  they  average  ^^^-^ 
of  an  inch. 

The  structure  of  the  ultimate  nervous  filament  is  as  follows: 
The  exterior  of  each  filament  consists  of  a  colorless,  transparent 
tubular  membrane,  which  is  seen  with  some  difficulty  in  the  natural 
condition  of  the  fibre,  owing  to  the  extreme  delicacy  of  its  texture, 
and  to  its  cavity  being  completely  filled  with  a  substance  yerj 
similar  to  it  in  refractive  power.  In  the  interior  of  this  tubular 
membrane  there  is  contained  a  thick,  softish,  semi-fluid  nervous 
matter,  which  is  white  and  glistening  by  reflected  light,  and  is 
called  the  "white  substance  of  Schwann."  Finally,  running  longi- 
tudinally through  the  central  part  of  each  filament,  is  a  narrow 
ribbon-shaped  cord,  of  rather  firm  consistency,  and  of  a  semi- 
transparent  grayish  color.  This  central  portion  is  called  the  "axis 
cylinder,"  or  the  "  flattened  band."  It  is  enveloped  everywhere  by 
the  semi-fluid  white  substance,  and  the  whole  invested  by  the  ex- 
ternal tubular  membrane. 

When  nervous  matter  is  prepared  for  the  microscope  and  exa- 
mined by  transmitted  light,  two  remarkable  appearances  are 
observed  in  its  filaments,  produced  by  the  contact  of  foreign  sub- 
stances. In  the  first  place  the  unequal  pressure,  to  which  the  fila- 
ments are  accidentally  subjected  in  the  process  of  dissection  and 
preparation,  produces  an  irregularly  bulging  or  varicose  appearance 
in  them  at  various  points,  owing  to  the  readiness  with  which  the 


OF    THE    NERVOUS    SYSTEM. 


309 


Nervous  Filaments  from  white  substance  of 
brain. — a,  a,  a.  Soft  substance  of  the  filaments  pressed 
out,  and  floating  in  irregularly  rounded  drops. 


semi-fluid  white  substance  in  their  interior  is  displaced  in  different 
directions.  (Fig.  118.)  Sometimes  spots  may  be  seen  here  and 
there,  where  the  nervous 
matter  has  been  entirely 
pressed  apart  in  the  centre 
of  a  filament,  so  that  there 
appears  to  be  an  entire  break 
in  its  continuity,  while  the 
investing  membrane  may  be 
still  seen,  passing  across  from 
one  portion  to  the  other. 
When  a  nervous  filament  is 
torn  across  under  the  micro- 
scope and  subjected  to  pres 
sure,  a  certain  quantity  of  the 
semi-fluid  white  substance  is 
pressed  out  from  its  torn 
extremity,  and  may  be  en- 
tirely separated  from  it,  so 
as  to  present  itself  under  the 

form  of  irregularly  rounded  drops  of  various  sizes  (a,  a,  a),  scat- 
tered over  the  field  of  the  microscope.  The  varicose  appearance 
above  alluded  to  is  more  frequently  seen  in  the  smaller  nervous 
filaments  from  the  brain  and  spinal  cord,  owing  to  their  soft  con- 
sistency and  the  readiness  with  which  they  yield  to  pressure. 

The  second  effect  produced  by  the  artificial  preparation  of  the 
nervous  matter  is  a  partial  coagulation  of  the  white  substance  of 
Schv/ann.  In  its  natural  condition  this  substance  has  the  same 
consistency  throughout,  and  appears  perfectly  transparent  and 
homogeneous  by  transmitted  light.  As  soon,  however,  as  the  nerv- 
ous filament  is  removed  from  its  natural  situation,  and  brought  in 
contact  with  air,  water,  or  other  unnatural  fluids,  the  soft  substance 
immediately  under  the  investing  membrane  begins  to  coagulate. 
It  increases  in  consistency,  and  at  the  same  time  becomes  more 
highly  refractive ;  so  that  it  presents  on  each  side,  immediately 
underneath  the  investing  membrane,  a  thin  layer  of  a  peculiar 
glistening  aspect.  (Fig.  119.)  At  first,  this  change  takes  place 
only  in  the  outer  portions  of  the  white  substance  of  Schwann. 
The  coagulating  process,  however,  subsequently  goes  on,  and 
gradually  advances   from  the   edges  of  the   filament  toward  its 


310 


GENERAL    STRUCTURE    AND    FUNCTIONS 


centre,  until  its  entire  thickness  after  a  time  presents  the  same  ap- 
pearance.    The  effect  of  the  same  process  can  also  be  seen  in  those 

portions  of  the  white  sub- 
stance which  have  been 
pressed  out  from  the  interior 
of  the  filaments,  and  which 
float  about  in  the  form  of 
drops.  (Fig.  118,  a.)  These 
drops  are  always  covered 
with  a  layer  of  coagulated 
material  which  is  thicker 
and  more  opaque  in  propor- 
tion to  the  length  of  time 
which  has  elapsed  since  the 
commencement  of  the  alter- 
ation. 

The  nervous  filaments 
have  essentially  the  same 
structure  in  the  brain  and 
spinal  cord  as  in  the  nervous 
trunks  and  branches;  only 
they  are  of  much  smaller 
size  in  the  former  than  in  the 
latter  situation.  In  the  nervous  trunks  and  branches,  however, 
outside  the  cranial  and  spinal  cavities,  there  exists,  superadded  to 
the  nervous  filaments  and  interwoven  with  them,  a  large  amount  of 
ordinary  areolar  or  fibrous  tissue,  which  protects  them  from  injury, 
and  gives  to  this  portion  of  the  nervous  system  a  peculiar  density 
and  resistance.  This  difference  in  consistency  between  the  white  sub- 
stance of  the  nerves  and  that  of  the  brain  and  spinal  cord  is  owing, 
therefore,  exclusively  to  the  presence  of  ordinary  fibrous  tissue  in 
the  nerves,  while  it  is  wanting  in  the  brain  and  spinal  cord.  The 
consistency  of  the  nervous  filaments  themselves  is  the  same  in 
each  situation. 

The  nervous  filaments  are  arranged,  in  the  nervous  trunks  and 
branches,  in  a  direction  nearly  parallel  with  each  other.  A  certain 
number  of  them  are  collected  in  the  form  of  a  bundle,  which  is 
invested  with  a  layer  of  fibrous  tissue,  in  which  run  the  small 
bloodvessels,  destined  for  the  nutrition  of  the  nerve.  These  pri- 
mary bundles  are  united  again  into  secondary,  the  secondary  into 
tertiary,  &;c.     A  nerve,  therefore,  consists  of  a  large  bundle  of  ulti- 


Nhrvohs  Filaments  from  sciatic  nerve,  showing 
their  coagulation.  —  At  a,  the  torn  extremity  of  a 
nervous  filament  with  the  axis  cylindA'  (6)  protruding 
from  it.  At  c,  the  white  substance  of  Schwann  is  nearly 
separated  by  accidental  compression,  but  the  axis- 
cyliuder  passes  across  the  ruptured  portion.  The  out- 
line of  the  tubular  membrane  is  also  seen  at  c  on  the 
outside  of  the  nervous  filament. 


OF    THE    NERVOUS    SYSTEM. 


311 


mate  filaments,  associated  with  each  other  in  larger  or  smaller 
packets,  and  bound  together  by  the  investing  fibrous  layers.  When 
a  nerve  is  said  to  become  branch- 
ed or  "  divided"  in  any  part  of 
its  course,  this  division  merely 
implies  that  some  of  its  filaments 
leave  the  bundles  with  which 
they  were  previously  associated, 
and  pursue  a  different  direction. 
(Fig.  120.)  A  nerve  which  ori- 
ginates, for  example,  from  the 
spinal  cord  in  the  region- of  the 
neck,  and  runs  down  the  upper 
extremity,  dividing  and  subdivid- 
ing, to  be  finally  distributed  to 
the  integument  and  muscles  of 
the  hand,  contains  at  its  point  of 
(jrigin  all  the  filaments  into  which 
it  is  afterward  divided,  and  which 
are  merely  separated  at  succes- 
sive points  from  the  main  bundle. 
The  ultimate  filaments,  accord- 
ingly, are  continuous  throughout, 
and  do  not  themselves  divide  at 
any  point  between  their  origin 
and  their  final  distribution. 

When  a  nerve,  furthermore,  is 
said  to  "inosculate"  with  another  nerve,  as  when  the  infra-orbital 
inosculates  with  the  facial,  or  the  cervical  nerves  inosculate  with 
each  other,  this  means  simply  that  some  of  the  filaments  composing 
the  first  nervous  bundle  separate  from  it,  and  cross  over  to  form  a 
part  of  the  second,  while  some  of  those  belonging  to  the  second 
cross  over  and  join  the  first  (Fig.  121);  but  the  individual  filaments 
in  each  instance  remain  continuous  and  preserve  their  identity 
throughout.  This  fact  is  of  great  physiological  importance ;  since 
the  white  or  fibrous  nerve-substance  is  everywhere  simply  an 
organ  of  transmission.  It  serves  to  convey  the  nervous  impulse  in 
various  directions,  from  without  inward,  or  from  within  outward ; 
and  as  each  nervous  filament  acts  independently  of  the  others,  it 
will  convey  an  impression  or  a  stimulus  continuously  from  its 
origin  to  its  termination,  and  will  always  have  the  same  character 
and  function  in  every  part  of  its  course. 


Division  of  a  Nerve,  showiug  portioa  of 
nervous  trunk  {a),  and  the  separation  of  its 
filaments  (6,  c,  d,  e). 


312 


GENERAL    STRUCTURE    AND    FUNCTIONS 


The  other  variety  of  nervous  matter  is  known  as  the  gray  sub- 
stance.    It  is  sometimes  called  "  cineritious  matter,"  and  sometimes 

Fig.  121. 


Inosculatiou  of  Nerves. 


"  vesicular  neurine,"  It  is  found  in  the  central  parts  of  the  spinal 
cord,  at  the  base  of  the  brain  in  isolated  masses,  and  is  also  spread 
out  as  a  continuous  layer  on  the  external  portions  of  the  cerebrum 
and  cerebellum.  It  also  constitutes  the  substance  of  all  the  gan- 
glia of  the  great  syrapathe- 


Fig.  122. 


Nerve   Cells,   intermingled  witli  fibres;   from 
teiiiilunar  ganglion  of  cat. 


tic.  Examined  by  the  micro- 
scope, it  consists  of  vesicles 
or  cells,  of  various  forms  and 
sizes,  imbedded  in  a  grayish, 
granular,  intercellular  sub- 
stance, and  containing  also, 
very  frequently,  granules  of 
grayish  pigmentary  matter. 
It  is  to  the  presence  of  this 
granular  pigment  that  this 
kind  of  nervous  matter  owes 
the  ashy  or  "cineritious"  color 
from  which  it  derives  its 
name.  The  cells  composing 
it  vary  in  size,  according  to 


OF    THE    NERVOUS    SYSTEM.  313 

Kolliker,  from  -^-q^^  to  -^^jj  of  an  inch.  The  largest  of  them  have 
a  very  distinct  nucleus  and  nucleolus.  (Fig.  122.)  Many  of  them 
are  provided  with  long  processes  or  projections,  which  are  some- 
times divided  into  two  or  three  smaller  branches.  These  cells  are 
intermingled,  in  all  the  collections  of  gray  matter,  with  nervous 
filaments,  and  are  entangled  with  their  extremities  in  such  a  man- 
ner that  it  is  exceedingly  difficult  to  ascertain  the  exact  nature  of 
the  anatomical  relations  existing  between  them.  It  is  certain  that 
in  some  instances  the  slender  processes  running  out  from  the  nerv- 
ous vesicles  become  at  last  continuous  with  the  filaments  ;  but  it  is 
not  known  whether  this  be  the  case  in  all  or  even  in  a  majority  of 
instances.  The  extremities  of  the  filaments,  however,  are  at  all 
events  brought  into  very  close  relation  with  the  vesicles  or  cells  of 
the  gray  matter. 

Every  collection  of  gray  matter,  whatever  be  its  situation  or 
relative  size  in  the  nervous  system,  is  called  a  ganglion  or  nervous 
centre.  Its  function  is  to  receive  impressions  conveyed  to  it  by  the 
nervous  filaments,  and  to  send  out  by  them  impulses  which  are  to 
be  transmitted  to  distant  organs.  The  ganglia,  therefore,  originate 
nervous  power,  so  to  speak ;  while  the  filaments  and  the  nerves 
only  transmit  it.  Now  we  shall  find  that,  in  the  structure  of  every 
nervous  system,  the  ganglia  are  connected,  first  with  the  different 
organs,  by  bundles  of  filaments  which  are  called  nerves;  and  secondly 
with  each  other,  by  other  bundles  which  are  termed  commissures. 
The  entire  system  is  accordingly  made  up  of  ganglia^  nerves^  and 
commissures. 

The  simplest  form  of  nervous  system  is  probably  that  found  in 
the  five-rayed  starfish.     This  animal  belongs  to  the  type  known 
as    radiata;  that  is,  animals  whose 
organs  radiate  from  a  central  point,  Pi?- 123. 

so  as  to  form  a  circular  series  of 
similar  parts,  each  organ  being  re- 
peated at  different  points  of  the 
circumference.  The  starfish  (Fig. 
123)  consists  of  a  central  mass, 
with  five  arms  or  limbs  radiating 
from  it.  In  the  centre  is  the  mouth, 
and  immediately  beneath  it  the  sto- 
mach or  digestive  cavity,  which 
sends  prolongations  into  every  one 
of  the  projecting  limbs.  There  is 
also  contained  in  each  limb  a  portion       n^hvocs  system  of  starp,. 


314  GENERAL    STRUCTURE    AND    FUNCTIONS 

of  the  glandular  and  muscular  systems,  and  the  whole  is  covered 
by  a  sensitive  integument.  The  nervous  system  consists  of  five 
similar  ganglia,  situated  in  the  central  portion,  at  the  base  of  the 
arms.  These  ganglia  are  connected  with  each  other  by  commis- 
sures, so  as  to  form  a  nervous  collar  or  chain,  surrounding  the 
orifice  of  the  digestive  cavity.  Each  ganglion  also  sends  off  nerves, 
the  filaments  of  which  are  distributed  to  the  organs  contained  in 
the  corresponding  limb. 

We  have  already  stated  that  the  proper  function  of  the  nervous 
system  is  to  enable  a  stimulus,  acting  upon  one  organ,  to  produce 
motion  or  excitement  in  another.  This  is  accomplished,  in  the 
starfish,  in  the  following  manner: — 

When  any  stimulus  or  irritation  is  applied  to  the  integument  of 
one  of  the  arms,  it  is  transmitted  by  the  nerves  of  the  integument 
to  the  ganglion  situated  near  the  mouth.  Arrived  here,  it  is 
received  by  the  gray  matter  of  the  ganglion,  and  immediately  con- 
verted into  an  impulse  which  is  sent  out  by  other  filaments  to  the 
muscles  of  the  corresponding  limb;  and  a  muscular  contraction  and 
movement  consequently  take  place.  The  muscles  therefore  contract 
in  consequence  of  an  irritation  which  has  been  applied  to  the  skin. 
This  is  called  the  "reflex  action"  of  the  nervous  system;  because  the 
stimulus  is  first  sent  inward  by  the  nerves  of  the  integument,  and 
then  returned  or  reflected  back  from  the  ganglion  upon  the  muscles. 
It  must  be  recollected  that  this  action  does  not  necessarily  indicate 
any  sensation  or  volition,  nor  even  any  consciousness  on  the  part  of 
the  animal.  The  function  of  the  gray  matter  is  simply  to  receive 
the  impulse  conveyed  to  it,  and  to  reflect  or  send  back  another ;  and 
this  may  be  accomplished  altogether  involuntarily,  and  without  the 
existence  of  any  conscious  perception. 

Where  the  irritation  applied  to  the  integument  is  of  an  ordinary 
character  and  not  very  intense,  it  is  simply  reflected,  as  above 
described,  from  the  corresponding  ganglion  back  to  the  same  limb. 
But  if  it  be  of  a  peculiar  character,  or  of  greater  intensity  than  usual, 
it  may  be  also  transmitted  by  the  commissures  to  the  neighboring 
ganglia;  and  so  two,  three,  four,  or  even  all  five  of  the  limbs  may 
be  set  in  motion  by  a  stimulus  applied  to  the  integument  of  one  of 
them.  Now,  as  all  the  limbs  of  the  animal  have  the  same  structure 
and  contain  the  same  organs,  their  action  will  also  be  the  same ; 
and  the  effect  of  this  communication  of  the  stimulus  from  one  to 
the  other  by  means  of  commissures  will  be  a  repetition,  or  rather 
a  simultaneous  production  of  similar  movements  in  different  parts 


OF    THE    NERVOUS    SYSTEM. 


315 


of  the  body.  According  to  the  character  and  intensity,  therefore, 
of  the  original  stimulus,  it  will  be  followed  by  a  response  from 
one,  several,  or  all  of  the  different  parts  of  the  animal  frame. 

It  will  be  seen  also  that  there  are  two  kinds  of  nervous  filaments, 
differing  essentially  in  their  functions.  One  set  of  these  fibres  run 
from  the  sensitive  surfaces  to  the  ganglion,  and  convey  the  nervous 
impression  inward.  These  are  called  sensitive  fibres.  The  other  set 
run  from  the  ganglion  to  the  muscles,  and  carry  the  nervous  im- 
pression outward.     These  are  called  motor  fibres. 

In  the  starfish,  wbere  the  body  is  composed  of  a  repetition  of  simi- 
lar parts  arranged  round  a  common  centre,  and  where  all  the  limbs 
are  precisely  alike  in  structure,  the  several  ganglia  composing  the 
nervous  system  are  also  similar  to  each  other,  and  act  in  the  same 
way.  But  in  animals  which  are  constructed  upon  a  different  plan, 
and  whose  bodies  are  composed  of  distinct  organs,  situated  in  dif- 
ferent regions,  we  find  that  the  nervous  ganglia,  presiding  over 
the  function  of  these  organs,  present  a  corresponding  degree  of 
dissimilarity. 

In  Ajylysia,  for  example,  which  belongs  to  the  type  of  mollusca, 
or  soft-bodied  animals,  the  digestive  apparatus  consists  of  a  mouth, 
an  oesophagus,  a  triple  stomach,  and  a  somewhat  convoluted  intes- 
tine. The  liver  is  large,  and  placed  on  one  side  of  the  body,  while 
the  gills,  in  the  form  of  vascular  laminae,  occupy  the  opposite  side. 
There  are  both  testicles  and  ovaries  in  the  same  animal,  the  male 
and  female  functions  co-existing,  as  in  many 
other  invertebrate  species.  All  the  organs, 
furthermore,  are  here  arranged  without  any 
reference  to  a  regular  or  symmetrical  plan. 
The  body  is  covered  with  a  muscular  man- 
tle, which  expands  at  the  ventral  surface 
into  a  tolerably  well  developed  "  foot,"  or 
organ  of  locomotion,  by  whicb  the  animal 
is  enabled  to  change  its  position  and  move 
from  one  locality  to  another. 

The  nervous  system  of  this  animal  is  con- 
structed upon  a  plan  corresponding  with 
that  of  the  entire  body.  (Fig.  124.)  There 
is  a  small  ganglion  (i)  situated  anteriorly, 
which  sends  nerves  to  the  commencement  nervol-s  svstem  of 
of  the  digestive  apparatus,  and  is  regarded  i^pL^itua^.  "rrL;. 
as  the  oesophageal   or  digestive  ganglion,     i^r^^i  gangUon.  3.3.  Pedai  or 

T  J'il        l_l-T-^-  1  /x        locomotory  ganglia       -t.    Respi- 

Immeaiately  behmd  it  is  a  larger  one  (i)     latory  ganguou. 


Fig.  124. 


316 


GENERAL  STRUCTURE  AND  FUNCTIONS 


Fig.  125. 


called  the  cephalic  or  cerebral  ganglion,  which  sends  nerves  to  the 
organs  of  special  sense,  and  which  is  regarded  as  the  seat  of  volition 
and  general  sensation  for  the  entire  body.  Following  this  is  a  pair 
of  ganglia  (3,  s),  the  pedal  or  locomotory  ganglia,  which  supply  the 
muscular  mantle  and  its  foot-like  expansion,  and  which  regulate  the 
movement  of  these  organs.  Finally,  another  ganglion  (4),  situated 
at  the  posterior  part  of  the  body,  sends  nerves  to  the  branchiae  or 
gills,  and  is  termed  the  branchial  or  respiratory  ganglion.  All 
these  nervous  centres  are  connected  by  commissures  with  the  central 
or  cerebral  ganglion,  and  may  therefore  act  either  independently  or 
in  association  with  each  other,  by  means  of  these  connecting  fibres. 
In  the  third  type  of  animals,  again,  viz.,  the  articulata,  the  gene- 
ral plan  of  structure  of  the  body  is  different  from  the  foregoing, 
and  the  nervous  system  is  accordingly  modified  to  correspond  with 
it.  In  these  animals,  the  body  is  composed  of  a  number  of  rings 
or  sections,  which  are  articulated  with  each  other  in  linear  series. 
A  very  good  example  of  this  type  may  be  found  in  the  common 
centipede,  or  scolopendra.  Here  the  body  is  com- 
posed of  twenty-two  successive  and  nearly  simi- 
lar articulations,  each  of  which  has  a  pair  of  legs 
attached,  and  contains  a  portion  of  the  glandular, 
respiratory,  digestive  and  reproductive  appara- 
tuses. The  animal,  therefore,  consists  of  a  repe- 
tition of  similar  compound  parts,  arranged  in  a 
longitudinal  chain  or  series.  The  only  exceptions 
to  this  similarity  are  in  the  first  and  last  articula- 
tions. The  first  is  large,  and  contains  the  mouth; 
the  last  is  small,  and  contains  the  anus.  The  first 
articulation,  which  is  called  the  "head,"  is  also 
furnished  with  eyes,  with  antennae,  and  with  a 
pair  of  jaws,  or  mandibles. 

The  nervous  system  of  the  centipede  (Fig.  125), 
corresponding  in  structure  with  the  above  plan, 
consists  of  a  linear  series  of  nearly  equal  and 
similar  ganglia  arranged  in  pairs,  situated  upon 
the  median  line,  along  the  ventral  surface  of  the 
alimentary  canal.  Each  pair  of  ganglia  is  con- 
nected with  the  integument  and  muscles  of  its 
own  articulation  by  sensitive  and  motor  filaments ; 
and  with  those  which  precede  and  follow  by  a 
double  cord  of  lonojitudinal  commissural  fibres.     In  the  first  articu- 


NERVons    System 
OF  Centipede. 


OF    THE    NERVOUS    SYSTEM.  317 

lation,  moreover,  or  the  head,  the  ganglia  are  larger  than  elsewhere, 
and  send  nerves  to  the  antennae  and  to  the  organs  of  special  sense. 
This  pair  is  termed  the  cerebral  ganglion,  or  the  "  brain." 

A  reflex  action  may  take  place,  in  these  animals,  through  either 
one  or  all  of  the  ganglia  composing  the  nervous  chain.  An 
impression  received  bj  the  integument  of  any  part  of  the  body 
may  be  transmitted  inward  to  its  own  ganglion  and  thence  reflected 
immediately  outward,  so  as  to  produce  a  movement  of  the  limbs 
belonging  to  that  articulation  alone;  or  it  may  be  propagated, 
through  the  longitudinal  commissures,  forward  or  back,  and  pro- 
duce simultaneous  movements  in  several  neighboring  articulations; 
or,  finally,  it  may  be  propagated  quite  up  to  the  anterior  pair  of 
ganglia,  or  "brain,"  where  its  reception  will  be  accompanied  with 
consciousness,  and  a  voluntary  movement  reflected  back  upon  any 
or  all  of  the  limbs  at  once.  The  organs  of  special  sense,  also,  com- 
municate directly  with  the  cerebral  ganglia;  and  impressions  con- 
veyed through  them  may  accordingly  give  rise  to  movements  in 
any  distant  part  of  the  body.  In  these  animals  the  ventral  ganglia, 
or  those  which  simply  stand  as  a  medium  of  communication  be- 
tween the  integument  and  the  muscles,  are  nearly  similar  through- 
out; while  the  first  pair,  or  those  which  receive  the  nerves  of  special 
sense,  and  which  exercise  a  general  controlling  power  over  the  rest 
of  the  nervous  system,  are  distinguished  from  the  remainder  by  a 
well-marked  preponderance  in  size. 

In  the  centipede  it  will  be  noticed  that  nearly  all  the  organs  and 
functions  are  distributed  in  an  equal  degree  throughout  the  whole 
length  of  the  body.  The  organs  of  special  sense  alone,  with  those 
of  mastication  and  the  functions  of  perception  and  volition,  are 
confined  to  the  head.  The  ganglia  occupying  this  part  are  there- 
fore the  only  ones  which  are  distinguished  by  any  external  pecu- 
liarities; the  remainder  being  nearly  uniform  both  in  size  and 
activity.  In  some  kinds  of  articulated  animals,  however,  particular 
functions  are  concentrated,  to  a  greater  or  less  extent,  in  particular 
parts  of  the  body ;  and  the  nervous  ganglia  which  preside  over 
them  are  modified  in  a  corresponding  manner.  In  the  insects, 
for  example,  the  body  is  divided  into  three  distinct  sections,  viz : 
the  head,  containing  the  organs  of  prehension,  mastication,  tact 
and  special  sense ;  the  chest,  upon  which  are  concentrated  the  or- 
gans of  locomotion,  the  legs  and  wings;  and  the  abdomen,  contain- 
ing the  greater  part  of  the  alimentary  canal,  together  with  the 
glandular  and  generative  organs.     As  the  insects  have  a  greater 


318  GENERAL    STRUCTURE    AND    FUNCTIONS 

amount  of  intelligence  and  activity,  than  the  centipedes  and  other 
worm-like  articulata,  and  as  the  organs  of  special  sense  are  more 
perfect  in  them,  the  cerebral  ganglia  are  also  unusually  developed,  and 
are  evidently  composed  of  several  pairs,  connected  by  commissures 
so  as  to  form  a  compound  mass.  As  the  organs  of  locomotion,  fur- 
thermore, instead  of  being  distributed,  as  in  the  centipede,  through- 
out the  entire  length  of  the  animal,  are  concentrated  upon  the  chest, 
the  locomotory  ganglia  also  preponderate  in  size  in  this  region  of 
the  body ;  while  the  ganglia  which  preside  over  the  secretory  and 
generative  functions  are  situated  together,  in  the  cavity  of  the  ab- 
domen. 

All  the  above  parts,  however,  are  connected,  in  the  same  manner 
as  previously  described,  with  the  anterior  or  cerebral  pair  of  gan- 
glia. In  all  articulate  animals,  moreover,  the  general  arrangement 
of  the  body  is  symmetrical.  The  right  side  is,  for  the  most  part, 
precisely  like  the  left,  as  well  in  the  internal  organs  as  in  the  ex- 
ternal covering  and  the  locomotory  appendages.  The  only  marked 
variation  between  different  parts  of  the  body  is  in  an  antero-pos- 
terior  direction ;  owing  to  difierent  organs  being  concentrated,  in 
some  cases,  in  the  head,  chest,  and  abdomen. 

Finally,  in  the  vertebrate  type  of  animals,  comprising  man,  the 
quadrupeds,  birds,  reptiles  and  fish,  the  external  parts  of  the  body, 
togetlier  with  the  locomotory  apparatus  and  the  organs  of  special 
sense,  are  symmetrical,  as  in  the  articulata;  but  the  internal  organs, 
especially  those  concerned  in  the  digestive  and  secretory  functions, 
are  unsymraetrical  and  irregular,  as  in  the  molluscs.  The  organs 
of  respiration,  however,  are  nearly  symmetrical  in  the  vertebrata, 
for  the  reason  that  the  respiratory  movements,  upon  which  the 
function  of  these  organs  is  immediately  dependent,  are  performed 
by  muscles  belonging  to  the  general  locomotory  apparatus.  The 
nervous  system  of  the  vertebrata  partakes,  accordingly,  of  the 
structural  arrangement  of  the  organs  under  its  control.  That  por- 
tion which  presides  over  the  locomotory,  respiratory,  sensitive,  and 
intellectual  functions  forms  a  system  by  itself,  called  the  cerebro- 
spinal, system.  This  system  is  arranged  in  a  manner  very  similar  to 
that  of  the  articulata.  It  is  composed  of  two  equal  and  symmetri- 
cal halves,  running  along  the  median  line  of  the  body,  the  different 
parts  of  which  are  connected  by  transverse  and  longitudinal  com- 
missures. Its  ganglia  occupy  the  cavities  of  the  cranium  and  the 
spinal  canal,  and  send  out  their  nerves  through  openings  in  the 
bony  walls  of  these  cavities. 


OF    THE    NERVOUS    SYSTEM. 


319 


Fig.  126. 


The  other  portion  of  the  nervous  system  of  vertebrata  is  that 
which  presides  over  the  functions  of  vegetative  life.  It  is  called 
the  ganglionic^  or  great  sympathetic  system.  Its  ganglia  are  situated 
anteriorly  to  the  spinal  column,  in  the  visceral  cavities  of  the  body, 
and  are  connected,  like  the  others,  by  transverse  and  longitudinal 
commissures.  This  part  of  the  nervous  system  is  symmetrical  in 
the  neck  and  thorax,  but  is  unsymmetrical  in  the  abdomen,  where 
it  attains  its  largest  size  and  its  most  complete  development. 

The  vertebrate  animals,  as  a  general  rule,  are  very  much  superior 
to  the  other  classes,  in  intelligence  and  activity,  as  well  as  in  the 
variety  and  complicated  character  of  their  motions;  while  their 
nutritive  or  vegetative  functions,  on  the  other  hand,  are  not  particu- 
larly well  developed.  Accordingly  we  find  that  in  these  animals  the 
cerebro-spinal  sj'^stem  of  nerves  preponderates  very  much,  in  im- 
portance and  extent,  over  that  of  the  great  sympathetic.  The  quan- 
tity of  nervous  matter  contained  in  the  brain  and  spinal  cord  is,  even 
in  the  lowest  vertebrate  animal,  very  much  greater  than  that  con- 
tained in  the  system  of  the  great 
sympathetic;  and  this  preponderance 
increases,  in  the  higher  classes,  just 
in  proportion  to  their  superiority  in 
intelligence,  sensation,  power  of  mo- 
tion, and  other  functions  of  a  purely 
animal  character. 

The  spinal  cord  is  very  nearly 
alike  in  the  different  classes  of  ver- 
tebrate animals.  It  is  a  nearly 
cylindrical  cord,  running  from  one 
end  of  the  spinal  canal  to  the  other, 
and  connected  at  its  anterior  ex- 
tremity with  the  ganglia  of  the 
brain.  (Fig.  126.)  It  is  divided,  by 
an  anterior  and  posterior  median 
fissure,  into  two  lateral  halves,  which 
still  remain  connected  with  each 
other  by  a  central  mass  or  commis- 
sure. Its  inner  portions  are  occupied 
by  gray  matter,  which  forms  a  con- 
tinuous  ganglionic   chain,  running      cerebro-spi^al  sy.tkm  op  max. 

from    one    extremity  of  the    cord    to     — l- cerebrum.  2.  Cerebellum   3,3,  .3.  Spinal 
.i  ,■!  -r  .  cord   aad   nerves.     4,   4.    Brachial   nerves. 

the  other.     Its  outer   portions   are    5, 5.  sacrai  nerves. 


320 


GENERAL    STRUCTURE    AND    FUNCTIONS 


composed  of  white  substance,  the  filaments  of  which  run  for  the 
most  part  in  a  longitudinal  direction,  connecting  the  different  parts 
of  the  cord  with  each  other,  and  the  cord  itself  with  the  ganglia 
of  the  brain. 

The  spinal  nerves  are  given  off  from  the  spinal  cord  at  regular 
intervals,  and  in  symmetrical  pairs;  one  pair  to  each  successive 
portion  of  the  body.  Their  filaments  are  distributed  to  the  integu- 
ment and  muscles  of  the  corresponding  regions.  In  serpents,  where 
locomotion  is  performed  by  simple,  alternate,  lateral  movements 
of  the  spinal  column,  the  spinal  cord  and  its  nerves  are  of  the 
same  size  throughout.  But  in  the  other  vertebrate  classes,  where 
there  exist  special  organs  of  locomotion,  such  as  fore  and  hind 
legs,  wings,  and  the  like,  the  spinal  cord  is  increased  in  size  at 
the  points  where  the  nerves  of  these  organs  are  given  off;  and  the 
nerves  themselves,  which  supply  the  limbs,  are  larger  than  those 
originating  from  other  parts  of  the  spinal  cord.  Thus,  in  the  hu- 
man subject  (Fig.  126),  the  cervical  nerves,  which  go  to  the  arms, 
and  the  sacral  nerves,  which  are  distributed  to  the  legs,  are  larger 
than  the  dorsal  and  lumbar  nerves.  They  form  also,  by  frequent 
inosculation,  two  remarkable  plexuses,  before  entering  their  corre- 
sponding limbs,  viz.,  the  brachial  plexus  above,  and  the  sacral 
plexus  below.  The  cord  itself,  moreover,  presents  two  enlargements 
at  the  point  of  origin  of  these  nerves,  viz.,  the  cervical  enlargement 
from  which  the  brachial  nerves  (4,  4)  are  given  off,  and  the  lum- 
bar enlargement  from  which  the  sacral  nerves  (5,  5)  originate. 
If  the  spinal  cord  be  examined  in  transverse  section  (Fig.  127), 

it  will  be  seen  that  the  gray 
Fig.  127.  matter  in  its  central  portion 

forms  a  double  crescentic- 
shaped  mass,  with  the  con- 
cavity of  the  crescents  turn- 
ed outward.  These  crescentic 
masses  of  gray  matter,  occu- 
pying the  two  lateral  halves 
of  the  cord,  are  united  with 
each  other  by  a  transverse 
band  of  the  same  substance, 
which  is  called  the  gray 
commissure  of  the  cord.  Di- 
rectly in  front  of  this  is  a 
transverse  band  of  white  substance,  connecting  in  a  similar  manner 


Transverse  Section  of  Spinal  Cokd. — a,h.  Spinal 
nerves  of  right  and  left  side,  showing  their  two  roots, 
d.  Origin  of  anterior  root.  e.  Origin  of  posterior  root. 
c.  Ganglion  of  posterior  root. 


OF    THE    NERVOUS    SYSTEM.  321 

the  white  portions  of  the  two  lateral  halves.     It  is  called  the  white 
commissure  of  the  cord. 

The  spinal  nerves  originate  from  the  cord  on  each  side  by  two 
distinct  roots ;  one  anterior,  and  one  posterior.  The  anterior  root 
(Fig.  127,  d)  arises  from  the  surface  of  the  cord  near  the  extremity 
of  the  anterior  peak  of  gray  matter.  The  posterior  root  (e)  origi- 
nates at  the  point  corresponding  with  the  posterior  peak  of  gray 
matter.  Both  roots  are  composed  of  a  considerable  number  of 
ultimate  nervous  filaments,  united  with  each  other  in  parallel 
bundles.  The  posterior  root  is  distinguished  by  the  presence  of  a 
small  ganglion  (c)  which  appears  to  be  incorporated  with  it,  and 
through  which  its  fibres  pass.  There  is  no  such  ganglion  on  the 
anterior  root.  The  two  roots  unite  with  each  other  shortly  after 
leaving  the  cavity  of  the  spinal  canal,  and  mingle  their  filaments 
in  a  single  trunk. 

It  will  be  seen,  on  referring  to  the  diagram  (Fig.  127),  that  each 
lateral  half  of  the  spinal  cord  is  divided  into  two  portions,  an 
anterior  and  a  posterior  portion.  The  posterior  peak  of  gray  mat- 
ter comes  quite  up  to  the  surface  of  the  cord,  and  it  is  just  at  this 
point  (e)  that  the  posterior  roots  of  the  nerves  have  their  origin. 
The  whole  of  the  white  substance  included  between  this  point  and 
the  posterior  median  fissure  is  called  the  posterior  column  of  the 
cord.  That  which  is  included  between  the  same  point  and  the 
anterior  median  fissure  is  the  arderior  column  of  the  cord.  The 
white  substance  of  the  cord  may  then  be  regarded  as  consisting 
for  the  most  part  of  four  longitudinal  bundles  of  nervous  filaments, 
viz.,  the  right  and  left  anterior,  and  the  right  and  left  posterior 
columns.  The  posterior  median  fissure  penetrates  deeply  into  the 
substance  of  the  cord,  quite  down  to  the  gray  matter,  so  that  the 
posterior  columns  appear  entirely  separated  from  each  other  in  a 
transverse  section ;  while  the  anterior  median  fissure  is  more  shal- 
low and  stops  short  of  the  gray  matter,  so  that  the  anterior  columns 
are  connected  with  each  other  by  the  white  commissure  above  men- 
tioned. 

By  the  encephalon  we  mean  the  whole  of  that  portion  of  the 
cerebro-spinal  system  which  is  contained  in  the  cranial  cavity.  It 
is  divided  into  three  principal  parts,  viz.,  the  cerebrum,  cerebellum, 
and  medulla  oblongata.  The  anatomy  of  these  parts,  though  some- 
what complicated,  can  be  readily  understood  if  it  be  recollected 
that  they  are  simply  a  double  series  of  nervous  ganglia,  connected  luith 
each  other  and  with  the  spinal  cord  by  transverse  and  longitudinal 
21 


322 


GENERAL    STRUCTURE    AND    FUNCTIONS 


commissures.  The  number  and  relative  size  of  these  ganglia,  in 
different  kinds  of  animals,  depend  upon  the  perfection  of  the  bodily 
organization  in  general,  and  more  especially  on  that  of  the  intelli- 
gence and  the  special  senses.  They  are  most  readily  described  by 
commencing  with  the  simpler  forms  and  terminating  with  the  more 
complex. 

The  brain  of  the  Alligator  (Fig.  128)  consists  of  five  pair  of 
ganglia,  ranged  one  behind  the  other  in  the  interior  of  the  cranium. 

The  first  of  these  are  two  rounded  masses 
(i),  lying  just  above  and  behind  the  nasal 
cavities,  which  distribute  their  nerves 
upon  the  Schneiderian  mucous  mem- 
brane. These  are  the  olfactory  ganglia. 
They  are  connected  with  the  rest  of  the 
brain  by  two  long  and  slender  commis- 
sures, the  "olfactory  commissures."  The 
next  pair  (2)  are  somewhat  larger  and  of 
a  triangular  shape,  when  viewed  from 
above  downward.  They  are  termed  the 
"  cerebral  ganglia,"  or  the  hemispheres. 
Imm.ediately  following  them  are  two 
quadrangular  masses  (3)  which  give  ori- 
gin to  the  optic  nerves,  and  are  called 
therefore  the  optic  ganglia.  They  are 
termed  also  the  "optic  tubercles;"  and 
in  some  of  the  higher  animals,  where 
they  present  an  imperfect  division  into 
four  nearly  equal  parts,  they  are  known  as  the  "  tubercula  quadri- 
gemina."  Behind  them,  we  have  a  single  triangular  collection 
of  nervous  matter  (4),  which  is  called  the  cerebellum.  Finally,  the 
upper  portion  of  the  cord,  just  behind  and  beneath  the  cerebellum, 
is  seen  to  be  enlarged  and  spread  out  laterally,  so  as  to  form  a 
broad  oblong  mass  (^),  the  medulla  oblongata.  It  is  from  this  latter 
portion  of  the  brain  that  the  pneumogastric  or  respiratory  nerves 
originate,  and  its  ganglia  are  therefore  sometimes  termed  the  "pneu- 
mogastric" or  "  respiratory"  ganglia. 

It  will  be  seen  that  the  posterior  columns  of  the  cord,  as  they 
diverge  laterally,  in  order  to  form  the  medulla  oblongata,  leave  be- 
tween them  an  open  space,  which  is  continuous  with  the  posterior 
median  fissure  of  the  cord.  This  space  is  known  as  the  "  fourth 
ventricle."     It  is  partially  covered  in  by  the  backward  projection 


Brain  of  Allioator. — 1.  Ol- 
factory ganglia.  2.  Hemisplieres.  3. 
Optic  tubercles.     4.  Cerebellum.     5. 

Medulla  oblongata. 


OF    THE    NERVOUS    SYSTEM. 


323 


of  the  cerebellum,  but  in  the  alligator  is  still  somewhat  open  pos- 
teriorly, presenting  a  kind  of  chasm  or  gap  between  the  two  lateral 
halves  of  the  medulla  oblongata. 

The  chain  of  ganglia  which  compose  the  brain,  being  arranged 
in  pairs  as  above  described,  are  separated  from  each  other  on  the 
two  sides  by  a  longitudinal  median  fissure,  which  is  continuous 
with  the  posterior  median  fissure  of  the  cord.  In  the  brain  of 
the  alligator  this  fissure  appears  to  be  interrupted  at  the  cerebellum  ; 
but  in  the  higher  classes,  where  the  lateral  portions  of  the  cere- 
bellum are  more  highly  developed,  as  in  the  human  subject  (Fig.  126), 
they  are  also  separated  from  each  other  posteriorly  on  the  median 
line,  and  the  longitudinal  median  fissure  is  complete  througbout. 

In  hirds^  the  hemispheres  are  of  much  larger  size  than  in  rep- 
tiles, and  partially  conceal  th.e  optic  ganglia.  The  cerebellum, 
also,  is  very  well  developed  iu  this  class,  and  presents  on  its  sur- 
face a  number  of  transverse  foldings  or  convolutions,  by  which 
the  quantity  of  gray  matter  which  it  contains  is  considerably  in- 
creased. The  cerebellum  bere  extends  so  far  backward  as  almost 
completely  to  conceal  the  medulla  oblongata  and  the  fourth  ven- 
tricle. 

In  the  quadrupeds^  the  hemispheres  and  cerebellum  attain  a  still 
greater  size  in  proportion  to  the  remaining  parts  of  tbe  brain. 
There  are  also  two  other  pairs 
of  ganglia,  situated  beneath  the 
hemispheres,  and  between  them 
and  thetubercula  quadrigemina. 
These  are  the  corpora  striata  in 
front  and  the  optic  thalami  behind. 
In  Fig.  129  is  shown  the  brain  of 
the  rabbit,  with  the  hemispheres 
laid  open  and  turned  aside,  so  as 
to  show  the  internal  parts  in  their 
natural  situation.  The  olfactory 
ganglia  are  seen  in  front  (i)  con- 
nected with  the  remaining  parts 
by  the  olfactory  commissures. 
The  separation  of  the  hemispheres 
(2,2)  shows  the  corpora  striata  (3) 
and  the  optic  thalami  (4).  Then 
come  the  tubercula  quadrigemina 
(5),  which  are  here  composed,  as 


Brain  of  Rabbit,  vieived from  above. — 
1.  Olfactory  ganglia.  2.  Hemispheres,  turned 
aside.  3.  Corpora  striata.  4.  Optic  thalami. 
5.  Tubercula  quadrigemina.     6.  Cerebellum. 


324 


GENERAL  STRUCTURE  AND  FUNCTIONS 


above  mentioned,  of  four  rounded  masses,  nearly  similar  in  size.  The 
cerebellum  (e)  is  considerably  enlarged  by  the  development  of  its 
lateral  portions,  and  shows  an  abundance  of  transverse  convolutions. 
It  conceals  from  view  the  fourth  ventricle  and  most  of  the  medulla 
oblongata. 

In  other  species  of  quadrupeds  the  hemispheres  increase  in  size 
so  as  to  project  entirely  over  the  olfactory  ganglia  in  front,  and  to 
cover  in  the  tubercula  quadrigemina  and  the  cerebellum  behind. 
The  surface  of  the  hemispheres  also  becomes  covered  with  numer- 
ous convolutions,  which  are  curvilinear  and  somewhat  irregular 
in  form  and  direction,  instead  of  being  transverse,  like  those  of  the 
cerebellum.  In  man,  the  development  of  the  hemispheres  reaches 
its  highest  point;  so  that  they  preponderate  altogether  in  size  over 
the  rest  of  the  ganglia  constituting  the  brain.  In  the  human  brain, 
accordingly,  when  viewed  from  above  downward,  there  is  nothing 
to  be  seen  but  the  convex  surfaces  of  the  hemispheres ;  and  even 
in  a  posterior  view,  as  seen  in  Fig.  126,  they  conceal  everything 
but  a  portion  of  the  cerebellum.  All  the  remaining  parts,  how- 
ever, exist  even  here,  and  have  the  same  connections  and  relative 
situation  as  in  other  instances.  They  may  be  best  studied  in  the 
following  order. 

As  the  spinal  cord,  in  the  human  subject,  passes  upward  into 
the  cranial  cavity,  it  enlarges  into  the  medulla  oblongata  as  already 
described.  The  medulla  oblongata  presents  on  each  side  three  pro- 
jections, two  anterior  and  one  posterior.  The  middle  projections 
on  its  anterior  surface  (Fig.  130,  i,  i),  which 
are  called  the  anterior  pyramds^  are  the  con- 
tinuation of  the  anterior  columns  of  the  cord. 
They  pass  onward,  underneath  the  transverse 
fibres  of  the  pons  Varolii,  run  upward  to  the 
corpora  striata,  pass  through  these  bodies,  and 
radiate  upward  and  outward  from  their  exter- 
nal surface,  to  terminate  in  the  gray  matter  of 
the  hemispheres.  The  projections  immedi- 
ately on  the  outside  of  the  anterior  pyramids, 
in  the  medulla  oblongata,  are  the  olivary  bodies 
(2,  2).  They  contain  in  their  interior  a  thin 
layer  of  gray  matter  folded  upon  itself,  the 
functions  and  connections  of  which  are  but 
little  understood,  and  are  not,  apparently,  of 
very  great  importance. 


Fis.  130. 


Medclla  Oblongata 
OF  Human  Brain,  ante- 
rior view. — 1,  1.  Anterior  py- 
ramids. 2,  2.  Olivary  bodies. 
3,  3.  Kestiform  bodies.  4.  De- 
cussation of  tlie  anterior  co- 
lamns.  The  medulla  oblong- 
ata is  seen  terminated  above 
by  the  transverse  fibres  of  the 
pons  Varolii. 


OF    THE    NERVOUS    SYSTEM.  325 

The  anterior  columns  of  the  cord  present,  at  the  lower  part  of  the 
medulla  oblongata,  a  remarkable  interchange  or  crossing  of  their 
fibres  (4).  The  fibres  of  the  left  anterior  column  pass  across  the 
median  line  at  this  spot,  and  becoming  continuous  with  the  right 
anterior  pyramid,  are  finally  distributed  to  the  right  side  of  the 
cerebrum;  while  the  fibres  of  the  right  anterior  column,  passing 
over  to  the  left  anterior  pyramid,  are  distributed  to  the  left  side  of 
the  cerebrum.  This  interchange  or  crossing  of  the  nervous  fibres 
is  known  as  the  decussation  of  the  anterior  columns  of  the  cord. 

The  posterior  columns  of  the  cord,  as  they  diverge  on  eacli  side 
the  fourth  ventricle,  form  the  posterior  and  lateral  projections  of 
the  medulla  oblongata  (3,  3).  They  are  sometimes  called  the  "resti- 
form  bodies,"  and  are  extremely  important  parts  of  the  brain. 
They  consist  in  great  measure  of  the  longitudinal  filaments  of 
the  posterior  columns,  which  pass  upward  and  outward,  and  are 
distributed  partly  to  the  gray  matter  of  the  cerebellum.  The 
remainder  then  pass  forward,  underneath  the  tubercula  quadri- 
gemina,  into  and  through  the  optic  thalami;  and  radiating  thence 
upward  and  outward,  are  distributed,  like  the  continuation  of  the 
anterior  columns,  to  the  gray  matter  of  the  cerebrum.  The  resti- 
form  bodies,  however,  in  passing  upward  to  the  cerebellum,  are 
supplied  with  some  fibres  from  the  anterior  columns  of  the  cord, 
which,  leaving  the  lower  portion  of  the  anterior  pyramids,  join  the 
restiform  bodies,  and  are  distributed  with  them  to  the  cerebellum. 
From  this  description  it  will  be  seen  that  both  the  cerebrum  and 
the  cerebellum  are  supplied  with  filaments  from  both  the  anterior 
and  posterior  columns  of  the  cord. 

In  the  substance  of  each  restiform  body,  moreover,  there  is  im- 
bedded a  ganglion  which  gives  origin  to  the  pneumogastric  nerve, 
and  presides  over  the  functions  of  respiration.  This  ganglion  is 
surrounded  and  covered  by  the  longitudinal  fibres  passing  upward 
from  the  cord  to  the  cerebellum,  but  may  be  discovered  by  cutting 
into  the  substance  of  the  restiform  body,  in  which  it  is  buried.  It 
is  the  first  important  ganglion  met  with,  in  dissecting  the  brain 
from  below  upward. 

While  the  anterior  columns  are  passing  beneath  the  pons  Varolii, 
they  form,  together  with  the  continuation  of  the  posterior  columns 
and  the  transverse  fibres  of  the  pons  itself,  a  rounded  prominence 
or  tuberosity,  which  is  known  by  the  name  of  the  tuher  annulare. 
In  the  deeper  portions  of  this  protuberance  there  is  situated,  among 
the  longitudinal  fibres,  another  collection  of  gray  matter,  which. 


326 


GENEEAL  STRUCTURE  AND  FUNCTIONS 


though  not  of  large  size,  has  very  important  functions  and  connec- 
tions.    This  is  known  as  the  ganglion  of  the  tuher  annulare. 

Situated  almost  immediately  above  these  parts  we  have  the  cor- 
pora striata  in  front,  and  the  optic  thalami  behind,  nearly  equal  in 
size,  and  giving  passage,  as  above  described,  to  the  fibres  of  the 
anterior  and  posterior  columns.  Behind  them  still,  and  on  a  little 
lower  level,  are  the  tubercula  quadrigemina,  giving  origin  to  the 
optic  nerves.  The  olfactory  ganglia  rest  upon  the  cribriform  plate 
of  the  ethmoid  bone,  and  send  the  olfactory  filaments  through  the 
perforations  in  this  plate,  to  be  distributed  upon  the  mucous  mem- 
brane of  the  upper  and  middle  turbinated  bones.  The  cerebellum 
covers  in  the  fourth  ventricle  and  the  posterior  surface  of  the 
medulla  oblongata ;  and  finally  the  cerebrum,  which  has  attained 
'the  size  of  the  largest  ganglion  in  the  cranial  cavity,  extends  so  far 
in  all  directions,  forward,  backward,  and  laterally,  as  to  form  a  con- 
voluted arch  or  vault,  completely  covering  all  the  remaining  parts 
of  the  encephalon. 

The  entire  brain  may  therefore  be  regarded  as  a  connected  series 
of  ganglia,  the  arrangement  of  which  is  shown  in  the  accompany- 
ing diagram.  (Fig.  131.)     These 
^ig-l^l-  ganglia  occur  in  the  following 

order,  counting  from  before  back- 
ward: 1st.  The  olfactory  gan- 
glia. 2d.  The  cerebrum  or  hemi- 
spheres. 3d.  The  corpora  striata. 
4th.  The  optic  thalami.  5th.  The 
tubercula  quadrigemina.  6th. 
The  cerebellum.  7th.  The  gan- 
glion of  the  tuber  annulare.  And 
8th.  The  ganglion  of  the  medulla 
oblongata.  Of  these  ganglia, 
only  the  hemispheres  and  cere- 
bellum are  convoluted,  while  the 
remainder  are  smooth  and  round- 
ed or  somewhat  irregular  in 
shape.  The  course  of  the  fibres 
coming  from  the  anterior  and 
posterior  columns  of  the  cord  is  also  to  be  seen  in  the  accompany- 
ing figure.  A  portion  of  the  anterior  fibres,  we  have  already  ob- 
served, pass  upward  and  backward,  with  the  restiform  bodies,  to  the 
cerebellum ;  while  the  remainder  run  forward  through  the  tuber 


Diagram  of  Human  Brain,  in  vertical  sec- 
tion;  ijhowi;ig  the  situation  of  the  different  gan- 
glia, and  the  course  of  the  fihres.  1  Olfactory 
g:inglion.  2.  Hemisphere.  3.  Corpus  striatum. 
4.  ijptic  thalamus.  .'5.  Tubercula  quadrigemina. 
6.  Cerebellum.  7.  Ganglion  of  tuber  annulare. 
8.  Ganglion  of  medulla  oblongata. 


OF    THE    NERVOUS    SYSTEM.  327 

annulare  and  the  corpus  striatum,  and  then  radiate  to  the  gray- 
matter  of  the  cerebrum.  The  posterior  fibres,  constituting  the  res- 
tiform  body,  are  distributed  partly  to  the  cerebellum,  and  then  pass 
forward,  as  previously  described,  underneath  the  tubercula  quadri- 
gemina  to  the  optic  thalami,  whence  they  are  also  finally  distributed 
to  the  gray  matter  of  the  cerebrum. 

The  cerebrum  and  cerebellum,  each  of  which  is  divided  into  two 
lateral  halves  or  "  lobes,"  by  the  great  longitudinal  fissure,  are  both 
provided  with  transverse  commissures,  by  which  a  connection  is 
established  between  their  right  and  left  sides.  The  great  trans- 
verse commissure  of  the  cerebrum  is  that  layer  of  white  substance 
which  is  situated  at  the  bottom  of  the  longitudinal  fissure,  and 
which  is  generally  known  by  the  name  of  the  "  corpus  callosum." 
Tt  consists  of  nervous  filaments,  which  originate  from  the  gray 
matter  of  one  hemisphere,  converge  to  the  centre  where  they  be- 
come parallel,  cross  the  median  line,  and  are  finally  distributed  to 
the  corresponding  parts  of  the  hemisphere  upon  the  opposite  side. 
The  transverse  commissure  of  the  cerebellum  is  the  pons  Varolii. 
Its  fibres  converge  from  the  gray  matter  of  the  cerebellum  on  one 
side,  and  pass  across  to  the  opposite ;  encircling  the  tuber  annulare 
with  a  band  of  parallel  curved  fibres,  to  which  the  name  of  "  pons 
Varolii"  has  been  given  from  their  resemblance  to  an  arched  bridge. 

The  cerebro-spinal  system,  therefore,  consists  of  a  series  of  gan- 
glia situated  in  the  cranio-spinal  cavities,  connected  with  each  other 
by  transverse  and  longitudinal  commissures,  and  sending  out  nerves 
to  the  corresponding  parts  of  the  body.  The  spinal  cord  supplies 
the  integument  and  muscles  of  the  neck,  trunk,  and  extremities ; 
while  the  ganglia  of  the  brain,  beside  supplying  the  corresponding 
parts  of  the  head,  preside  also  over  the  organs  of  special  sense,  and 
perform  various  other  functions  of  a  purely  nervous  character. 


328  OF    NERVOUS    IRRITABILITY 


CHAPTETl   II. 

OF   NERVOUS   IRRITABILITY   AND    ITS   MODE   OF 

ACTION. 

We  have  already  mentioned,  in  a  previous  chapter,  that  every 
organ  in  the  body  is  endowed  with  the  property  o^  irritability  ;  that 
is,  the  property  of  reacting  in  some  peculiar  manner  when  subjected 
to  the  action  of  a  direct  stimulus.  Thus  the  irritability  of  a  gland 
shows  itself  by  increased  secretion,  that  of  the  capillary  vessels  by 
congestion,  that  of  the  muscles  by  contraction.  Now  the  irritability 
of  the  muscles,  indicated  as  above  by  their  contraction,  is  extremely 
serviceable  as  a  means  of  studying  and  exhibiting  nervous  pheno- 
mena. We  shall  therefore  commence  this  chapter  by  a  study  of 
some  of  the  more  important  facts  relating  to  muscular  irritability. 

The  irritability  of  the  muscles  is  a  'property  inherent  in  the  mvscular 
fibre  itself.  The  existence  of  muscular  irritability  cannot  be  ex- 
plained on  any  known  physical  or  chemical  laws,  so  far  as  they 
relate  to  inorganic  substances.  It  must  be  regarded  simply  as  a 
peculiar  property,  directly  dependent  on  the  structure  and  consti- 
tution of  the  muscular  fibre;  just  as  the  property  of  emitting  light 
belongs  to  phosphorus,  or  that  of  combining  with  metals  to  oxygen. 
This  property  may  be  called  into  action  by  various  kinds  of  stimu- 
lus; as  by  pinching  the  muscular  fibre,  or  pricking  it  with  the  point 
of  a  needle,  the  application  of  an  acid  or  alkaline  solution,  or  the 
discharge  of  a  galvanic  battery.  All  these  irritating  applications 
are  immediately  followed  by  contraction  of  the  muscular  fibre. 
This  contraction  will  even  take  place  under  the  microscope,  when 
the  fibre  is  entirely  isolated,  and  removed  from  contact  with  any 
other  tissue ;  showing  that  the  properties  of  contraction  and  irrita- 
bility reside  in  the  fibre  itself,  and  are  not  communicated  to  it  by 
other  parts. 

Muscular  irritability  continues  for  a  certain  time  after  death.  The 
stoppage  of  respiration  and  circulation  does  not  at  once  destroy 
the  vital  properties  of  the  tissues,  but  nearly  all  of  them  retain 
these  properties  to  a  certain  extent  for  some  time  afterward.  It  is 
only  when  the  constitution  of  the  tissues  has  become  altered  by 


AND    ITS    MODE    OF    ACTION. 


329 


being  deprived  of  blood,  and  by  the  consequent  derangement  of 
the  nutritive  process,  that  their  characteristic  properties  are  finally 
lost.  Thus,  in  the  muscles,  irritability  and  contractility  may  be 
easily  shown  to  exist  for  a  short  time  after  death  by  applying  to  the 
exposed  muscular  fibre  the  same  kind  of  stimulus  that  we  have 
already  found  to  affect  it  during  life.  It  is  easy  to  see,  in  the 
muscles  of  the  ox,  after  the  animal  has  been  killed,  flayed,  and 
eviscerated,  different  bundles  of  muscular  fiibres  contracting  irregu- 
larly for  a  long  time,  where  they  are  exposed  to  the  contact  of  the 
air.  Even  in  the  human  subject  the  same  phenomenon  may  be 
seen  in  cases  of  amputation;  the  exposed  muscles  of  the  amputated 
limb  frequently  twitching  and  quivering  for  many  minutes  after 
their  separation  from  the  body. 

The  duration  of  muscular  irritability,  after  death,  varies  consi- 
derably in  different  classes  of  animals.  It  disappears  most  rapidly 
in  those  whose  circulation  and  respiration  are  naturally  the  most 
active;  while  it  continues  for  a  longer  time  in  those  whose  circula- 
tion and  respiration  are  sluggish.  Thus  the  muscular  irritability 
in  birds  continues  only  a  few  minutes  after  the  death  of  the  ani- 
mal. That  of  quadrupeds  lasts  somewhat  longer ;  while  in  reptiles 
it  remains,  under  favorable  circumstances,  for  many  hours.  The 
cause  of  this  difference  is  probably  that  in  birds  and  quadrupeds, 
the  tissues  being  very  vascular,  and  the  molecular  changes  of  nu- 
trition going  on  with  rapidity,  the  constitution  of  the  muscular 
fibre  becomes  so  rapidl}'^  altered  after  the  circula- 
tion has  ceased,  that  its  irritability  soon  disap- 
pears. In  reptiles,  on  the  other  hand,  the  tissues 
are  less  vascular  than  in  birds  and  quadrupeds, 
and  all  the  nutritive  changes  go  on  more  slowly. 
Eespiration  and  circulation  can  therefore  be  dis- 
pensed with  for  a  longer  period,  before  the  consti- 
tution of  the  tissues  becomes  so  much  altered  as 
to  destroy  altogether  their  vital  properties. 

Owing  to  this  peculiarity  of  the  cold-blooded 
animals,  their  tissues  may  be  used  with  great  ad- 
vantage for  purposes  of  experiment.  If  a  frog's 
leg,  for  example,  be  separated  from  the  body  of 
the  animal  (Fig.  132),  the  skin  removed,  and  the 
poles  of  a  galvanic  apparatus  applied  to  the  sur-  frog's  leo, 
face  of  the  muscle  (a,  b),  a  contraction  takes  place     "^''"^  po'<^^  °^  s'^'- 

1  .  .      .  1  1  1        T      ^  vanic  battery  applied 

every  time  the  circuit  is  completed  and  a  discharge     to  the  muscles  at  a,  6. 


Fig.  132. 


330  OF    NERVOUS    IRRITABILITY 

passed  through  the  tissues  of  the  limb.  The  leg  of  the  frog,  pre- 
pared in  this  way,  may  be  employed  for  a  long  time  for  the  pur- 
pose of  exhibiting  the  effect  of  various  kinds  of  stimulus  upon  the 
muscles.  All  the  mechanical  and  chemical  irritants  which  we 
have  mentioned,  pricking,  pinching,  cauterizing,  galvanism,  &c.,  act 
with  more  or  less  energy  and  promptitude,  though  the  most  efficient 
of  all  is  the  electric  discharge. 

Continued  irritation  exhausts  the  irritability  of  the  muscles.  It  is 
found  that  the  irritability  of  the  muscles  wears  out  after  death  more 
rapidly  if  they  be  artificially  excited,  than  if  they  be  allowed  to 
remain  at  rest.  During  life,  the  only  habitual  excitement  of  mus- 
cular contraction  is  the  peculiar  stimulus  conveyed  by  the  nerves. 
After  death  this  stimulus  may  be  replaced  or  imitated,  to  a  certain 
extent,  by  other  irritants  ;  but  their  application  gradually  exhausts 
the  contractility  of  the  muscle  and  hastens  its  final  disappearance. 
Under  ordinary  circumstances,  the  post-mortem  irritability  of  the 
muscle  remains  until  the  commencement  of  cadaveric  rigidity. 
When  this  has  become  fairly  established,  the  muscles  will  no  longer 
contract  under  the  application  of  an  artificial  stimulus. 

Certain  poisonous  substances  have  the  power  of  destroying  the 
irritability  of  the  muscles  by  a  direct  action  upon  their  tissue. 
Sulpho-cyanide  of  potassium,  for  example,  introduced  into  the  cir- 
culation in  sufficient  quantity  to  cause  death,  destroys  entirely  the 
muscular  irritability,  so  that  no  contraction  can  afterward  be  pro- 
duced by  the  application  of  an  external  stimulant. 

Nervous  Irritability. — The  irritability  of  the  nerves  is  the  pro- 
perty by  which  they  may  be  excited  by  an  external  stimulus,  so  as 
to  be  called  into  activity  and  excite  in  their  turn  other  organs  to 
which  their  filaments  are  distributed.  When  a  nerve  is  irritated, 
therefore,  its  power  of  reaction,  or  its  irritability,  can  only  be  esti- 
mated by  the  degree  of  excitement  produced  in  the  organ  to  which  the 
nerve  is  distributed.  A  nerve  running  from  the  integument  to  the 
brain  produces,  when  irritated,  a  painful  sensation ;  one  distributed 
to  a  glandular  organ  produces  increased  secretion ;  one  distributed 
to  a  muscle  produces  contraction.  Of  all  these  effects,  muscular 
contraction  is  found  to  be  the  best  test  and  measure  of  nervous 
irritability,  for  purposes  of  experiment.  Sensation  cannot  of  course 
be  relied  on  for  this  purpose,  since  both  consciousness  and  volition 
are  abolished  at  the  time  of  death.  The  activity  of  the  glandular 
organs,  owing  to  the  stoppage  of  the  circulation,  disappears  also 
very  rapidly,  or  at  least  cannot  readily  be  demonstrated.     The 


AND    ITS    MODE    OF    ACTION. 


331 


Fig.  133. 


M 


contractility  of  the  muscles,  however,  lasts,  as  we  have  seen,  for  a 
considerable  time  after  death,  and  may  accordingly  be  employed 
with  great  readiness  as  a  test  of  nervous  irritability.  The  manner 
of  its  employment  is  as  follows: — 

The  leg  of  a  frog  is  separated  from  the  body  and  stripped  of  its 
integument;  the  sciatic  nerve  having  been  previously  dissected 
out  and  cut  off  at  its  point  of  emergence  from  the 
spinal  canal,  so  that  a  considerable  portion  of  it 
remains  in  connection  with  the  separated  limb. 
(Fig,  133.)  If  the  two  poles  of  a  galvanic  appa- 
ratus be  now  placed  in  contact  with  different 
points  (a  b)  of  the  exposed  nerve,  and  a  discharge 
allowed  to  pass  between  them,  at  the  moment 
of  discharge  a  sudden  contraction  takes  place  in 
the  muscles  below.  It  will  be  seen  that  this  ex- 
periment is  altogether  different  from  the  one  re- 
presented in  Fig.  182.  In  that  experiment  the 
galvanic  discharge  is  passed  througli  the  muscles 
themselves,  and  acts  upon  them  by  direct  stim- 
ulus. Here,  however,  the  discharge  passes  only 
from  a  to  &  through  the  tissues  of  the  nerve,  and 
acts  directly  upon  the  nerve  alone ;  while  the 
nerve,  acting  upon  the  muscles  by  its  own  pecu- 
liar agency,  causes  in  this  way  a  muscular  con- 
traction. It  is  evident  that  in  order  to  produce 
this  effect,  two  conditions  are  equally  essential:  1st. 
The  irritability  of  the  muscles ;  and  2d.  The  irri- 
tability of  the  nerves.  So  long,  therefore,  as  the 
muscles  are  in  a  healthy  condition,  their  contraction,  under  the 
influence  of  a  stimulus  applied  to  the  nerve,  demonstrates  the 
irritability  of  the  latter,  and  may  be  used  as  a  convenient  measure 
of  its  intensity. 

The  irritdbility  of  the  nerve  continues  after  death.  The  knowledge 
of  this  fact  follows  from  what  has  just  been  said  with  regard  to  ex- 
perimenting upon  the  frog's  leg,  prepared  as  above.  The  irrita- 
bility of  the  nerve,  like  that  of  the  muscle,  depends  directly  upon 
its  anatomical  structure  and  constitution ;  and  so  long  as  these  re- 
main unimpaired,  the  nerve  will  retain  its  vital  properties,  though 
respiration  and  circulation  may  have  ceased.  For  the  same  reason, 
also,  as  that  given  above  with  regard  to  the  muscles,  nervous  irri- 
tability lasts  much  longer  after  death  in  the  cold-blooded  than  in 


Fror'  s  Leg,  with 
sciatic  nerve  (N)  at- 
tached.— a  b.  Poles  of 
galvanic  battery,  ap- 
plied to  nerve. 


332  OF    NERVOUS    IRRITABILITY 

the  warm-blooded  animals.  Various  artificial  irritants  may  be  em- 
ployed to  call  it  into  activity.  Pinching  or  pricking  the  exposed 
nerve  with  steel  instruments,  the  application  of  caustic  liquids,  and 
the  passage  of  galvanic  discharges,  all  have  this  effect.  The  electric 
current,  however,  is  much  the  best  means  to  employ  for  this  pur- 
pose, since  it  is  more  delicate  in  its  operation  than  the  others,  and 
will  continue  to  succeed  for  a  longer  time. 

The  nerve  is,  indeed,  so  exceedingly  sensitive  to  the  electric  cur- 
rent, that  it  will  respond  to  it  when  insensible  to  all  other  kinds  of 
stimulus.  A  frog's  leg  freshly  prepared  with  the  nerve  attached, 
as  in  Fig.  133,  will  react  so  readily  whenever  a  discharge  is  passed 
through  the  nerve,  that  it  forms  an  extremely  delicate  instrument 
for  detecting  the  presence  of  electric  currents  of  low  intensity,  and 
has  even  been  used  for  this  purpose  by  Matteucci,  under  the  name 
of  the  "  galvanoscopic  frog."  It  is  only  necessary  to  introduce  the 
nerve  as  part  of  the  electric  circuit;  and  if  even  a  very  feeble  cur- 
rent be  present,  it  is  at  once  betrayed  by  a  muscular  contraction. 

The  superiority  of  electricity  over  other  means  of  exciting  nerv- 
ous action,  such  as  mechanical  violence  or  chemical  agents,  pro- 
bably depends  upon  the  fact  that  the  latter  necessarily  alter  and 
disintegrate  more  or -less  the  substance  of  the  nerve,  so  that  its 
irritability  soon  disappears.  The  electric  current,  on  the  other 
hand,  excites  the  nervous  irritability  without  any  marked  injury  to 
the  substance  of  the  nervous  fibre.  Its  action  may,  therefore,  be 
continued  for  a  longer  period. 

Nervous  irritability^  like  that  of  the  muscles,  is  exhausted  by  repeated 
excitement.  If  a  frog's  leg  be  prepared  as  above,  with  the  sciatic 
nerve  attached,  and  allowed  to  remain  at  rest  in  a  damp  and  cool 
place,  where  its  tissue  will  not  become  altered  by  desiccation,  the 
nerve  will  remain  irritable  for  many  hours ;  but  if  it  be  excited, 
soon  after  its  separation  from  the  body,  by  repeated  galvanic  shocks, 
it  soon  begins  to  react  with  diminished  energy,  and  becomes  gra- 
dually less  and  less  irritable,  until  it  at  last  ceases  to  exhibit  any 
further  excitability.  If  it  be  now  allowed  to  remain  for  a  time  at 
rest,  its  irritability  will  be  partially  restored ;  and  muscular  con- 
tractions will  again  ensue  on  the  application  of  a  stimulus  to  the 
nerve.  Exhausted  a  second  time,  and  a  second  time  allowed  to  re- 
pose, it  will  again  recover  itself;  and  this  maybe  even  repeated 
several  times  in  succession.  At  each  repetition,  however,  the  re- 
covery of  nervous  irritability  is  less  complete,  until  it  finally  dis- 
appears altogether,  and  can  no  longer  be  recalled. 


AND    ITS    MODE    OF    ACTION.  383 

Yarious  accidental  circumstances  tend  to  diminisTi  or  destroy 
nervous  irritability.  The  action  of  the  woorara  poison,  for  example, 
destroys  at  once  the  irritabilit}'-  of  the  nerves;  so  that  in  animals 
killed  by  this  substance,  no  muscular  contraction  takes  place  on 
irritatinor  the  nervous  trunk.  Severe  and  sudden  mechanical  in- 
juries  often  have  the  same  effect;  as  where  death  is  produced  by 
violent  and  extensive  crushing  or  laceration  of  the  body  or  limbs. 
Such  an  injury  produces  a  general  disturbance,  or  shock  as  it  is 
called,  which  affects  the  entire  nervous  system,  and  destroys  or 
suspends  its  irritability.  The  effects  of  such  a  nervous  shock  may 
frequently  be  seen  in  the  human  subject  after  railroad  accidents, 
where  the  patient,  though  very  extensively  injured,  may  remain 
for  some  hours  without  feeling  the  pain  of  his  wounds.  It  is  only 
after  reaction  has  taken  place,  and  the  activity  of  the  nerves  has 
been  restored,  that  the  patient  begins  to  be  sensible  of  pain. 

It  will  often  be  found,  on  preparing  the  frog's  leg  for  experiment 
as  above,  that  immediately  after  the  limb  has  been  separated  from 
the  body  and  the  integument  removed,  the  nerve  is  destitute  of 
irritability.  Its  vitality  has  been  suspended  by  the  violence  in- 
flicted in  the  preparatory  operation.  In  a  few  moments,  however, 
if  kept  under  favorable  conditions,  it  recovers  from  the  shock,  and 
regains  its  natural  irritability. 

The  action. of  the  galvanic  current  upon  the  nerve,  as  first  shown 
by  the  experiments  of  Matteucci,  is  in  many  respects  peculiar.  If 
the  current  be  made  to  traverse  the  nerve  in  the  natural  direction 
of  its  fibres,  viz.,  from  its  origin  toward  its  distribution,  as  from  a 
to  b  in  Fig.  138,  it  is  called  the  direct  current.  If  it  be  made  to 
pass  in  the  contrary  direction,  as  from  b  to  a,  it  is  called  the  inverse 
current.  When  the  nerve  is  fresh  and  exceedingly  irritable,  a 
muscular  contraction  takes  place  at  both  the  commencement  and 
termination  of  the  current,  whether  it  be  direct  or  inverse.  But 
very  soon  afterward,  when  the  activity  of  the  nerve  has  become 
somewhat  diminished,  it  will  be  found  that  contraction  takes  place 
only  at  the  commencement  of  the  direct  and  at  the  termination  of  the 
inverse  current.  This  may  readily  be  shown  by  preparing  the  two 
legs  of  the  same  frog  in  such  a  manner  that  they  remain  connected 
with  each  other  by  the  sciatic  nerves  and  that  portion  of  the  spinal 
column  from  which  these  nerves  take  their  origin.  The  two  legs, 
so  prepared,  should  be  placed  each  in  a  vessel  of  water,  with  the 
nervous  connection  hanging  between  (Fig.  184).  If  the  positive 
pole,  a,  of  the  battery  be  now  placed  in  the  vessel  which  holds  leg 


334 


OF    NERVOUS    IRRITABILITY 


No.  1,  and  the  negative  pole,  J,  in  that  containing  leg  No.  2,  it  will 
be  seen  that  the  galvanic  current  will  traverse  the  two  legs  in  op- 
posite directions.  In  No.  1  it  will  pass  in  a  direction  contrary  to 
the  course  of  its  nervous  fibres,  that  is,  it  will  be  for  this  leg  an 

Fig.  134. 


inverse  current;  while  in  No.  2  it  will  pass  in  the  same  direction 
with  that  of  the  nervous  fibres,  that  is,  it  will  be  for  this  leg  a  direct 
current.  It  will  now  be  found  that  at  the  moment  when  the  cir- 
cuit is  completed,  a  contraction  takes  place  in  No.  2  by  the  direct 
current,  while  No.  1  remains  at  rest ;  but  at  the  time  the  circuit  is 
broken,  a  contraction  is  produced  in  No.  1  by  the  inverse  current, 
but  no  movement  takes  place  in  No.  2.  A  succession  of  alternate 
contractions  may  thus  be  produced  in  the  two  legs  by  repeatedly 
closing  and  opening  the  circuit.  If  the  position  of  the  poles,  a,  i, 
be  reversed,  the  effects  of  the  current  will  be  changed  in  a  corres- 
ponding manner. 

After  a  nerve  has  become  exhausted  by  the  direct  current,  it  is 
still  sensitive  to  the  inverse;  and  after  exhaustion  by  the  inverse, 
it  is  still  sensitive  to  the  direct.  It  has  even  been  found  by  Mat- 
teucci  that  after  a  nerve  has  been  exhausted  for  the  time  by  the  direct 
current,  the  return  of  its  irritability  is  hastened  by  the  subsequent 
passage  of  the  inverse  current;  so  that  it  will  become  again  sensi- 
tive to  the  direct  current  sooner  than  if  allowed  to  remain  at  rest. 
Nothing,  accordingly,  is  so  exciting  to  a  nerve  as  the  passage  of 
direct  and  inverse  currents,  alternating  with  each  other  in  rapid 
succession.  Such  a  mode  of  applying  the  electric  stimulus  is  that 
usually  adopted  in  the  galvanic  machines  used  in  medical  practice, 
for  the  treatment  of  certain  paralytic  affections.    In  these  machines, 


AND    ITS    MODE    OF    ACTION.  335 

tbe  electric  current  is  alternately  formed  and  broken  witli  great 
rapidity,  thus  producing  the  greatest  effect  upon  the  nerves  with 
the  smallest  expenditure  of  electricity.  Such  alternating  currents, 
however,  if  very  powerful,  exhaust  the  nervous  irritability  more 
rapidly  and  completely  than  any  other  kind  of  irritation ;  and  in 
an  animal  killed  by  the  action  of  a  battery  used  in  this  manner,  the 
nerves  may  be  found  to  be  entirely  destitute  of  irritability  from  the 
moment  of  death. 

The  irrilabiUty  of  the  nerves  is  distinct  from  that  of  the  muscles;  and 
the  two  may  be  destroyed  or  suspended  independently  of  each  other. 
When  the  frog's  leg  has  been  prepared  and  separated  from  the 
body,  with  the  sciatic  nerve  attached,  the  muscles  contract,  as  we 
have  seen,  whenever  the  nerve  is  irritated.  The  irritability  of  the 
nerve,  therefore,  is  manifested  in  this  instance  only  through  that  of 
the  muscle,  and  that  of  the  muscle  is  called  into  action  only  through 
that  of  the  nerve.  The  two  properties  may  be  separated  from  each 
other,  however,  by  the  action  of  tcoorara,  which  has  the  power,  as 
first  pointed  out  by  Bernard,  of  destroying  the  irritability  of  the 
nerve  without  affecting  that  of  the  muscles.  If  a  frog  be  poisoned 
by  this  substance,  and  the  leg  prepared  as  above,  the  poles  of  a 
galvanic  battery  applied  to  the  nerve  will  produce  no  effect ;  show- 
ing that  the  nervous  irritability  has  ceased  to  exist.  But  if  the 
galvanic  discharge  be  passed  directly  through  the  muscles,  contrac- 
tion at  once  takes  place.  The  muscular  irritability  has  survived 
that  of  the  nerves,  and  must  therefore  be  regarded  as  essentiallv 
distinct  from  it. 

It  will  be  recollected,  on  the  other  hand,  that  in  cases  of  death 
from  the  action  of  sulphocyanide  of  potassium,  the  muscular  irri- 
tability is  itself  destroyed ;  so  that  no  contractions  occur,  even  when 
the  galvanic  discharge  is  made  to  traverse  the  muscular  tissue. 

There  are,  therefore,  two  kinds  of  paralysis :  first,  a  muscular 
paralysis,  in  which  the  muscular  fibres  themselves  are  directly 
affected ;  and  second,  a  nervous  paralysis,  in  which  the  affection  is 
confined  to  the  nervous  filaments,  the  muscles  retaining  their  natural 
properties,  and  being  still  capable  of  contracting  under  the  influence 
of  a  direct  stimulus. 

Nature  of  the  Nervous  Force. — It  will  readily  be  seen  that  the 
nervous  force,  or  the  agency  by  which  the  nerve  acts  upon  a  muscle 
and  causes  its  contraction,  is  entirely  a  peculiar  one,  and  cannot  be 
regarded  as  either  chemical  or  mechanical  in  its  nature.  The  force 
which  is  exerted  by  a  nerve  in  a  state  of  activity  is  not  directly 


336  OF    NERVOUS    IRRITABILITY 

appreciable  in  any  way  by  the  senses,  and  can  be  judged  of  only 
by  its  efifect  in  causing  muscular  contraction.  This  peculiar  vitality 
of  the  nerve,  or,  as  it  is  sometimes  called,  the  "  nervous  force,"  does 
not  precisely  resemble  in  its  operation  any  of  the  known  physical 
forces.  It  has,  however,  a  partial  resemblance  in  some  respects  to 
electricity;  and  this  has  been  sufficient  to  lead  some  writers  into  the 
error  of  regarding  the  two  as  identical,  and  of  supposing  electricity 
to  be  really  the  force  acting  in  the  nerves,  and  operating  through 
them  upon  the  muscles.  The  principal  points  of  resemblance 
existing  between  the  two  forces,  and  which  have  been  used  in 
support  of  the  above  opinion,  are  the  following : — 

1st.  The  identity  of  their  effects  upon  the  muscular  fibre. 
2d.  The  rapidity  and  peculiarity  of  their  action,  by  which  the 
force  is  transmitted  almost  instantaneously  to  a  distant  point,  with- 
out producing  any  visible  effect  on  the  intervening  parts. 

3d.  The  extreme  sensibility  of  nerves  to  the  electric  current;  and 
4th.  The  phenomena  of  electrical  fishes. 

As  these  considerations  are  of  some  importance  in  settling  the 
question  which  now  occupies  us,  we  shall  examine  them  in  succes- 
sion. 

1st.  The  Identity  of  their  Effects  upon  the  Muscular  Fibre. — It  is 
very  true  that  the  muscular  fibre  contracts  under  the  influence  of 
electricity,  as  it  does  under  that  of  the  nervous  force.  This  fact, 
however,  does  not  show  the  identity  of  the  two  forces,  but  only 
that  they  are  both  capable  of  producing  one  particular  phenomenon; 
or  that  electricity  may  replace  or  imitate  the  nervous  force  in  its 
action  on  the  muscles.  But  there  are  various  other  agents,  as  we 
have  already  seen,  both  mechanical  and  chemical,  which  will  pro- 
duce the  same  effect,  when  applied  to  the  muscular  tissue.  Elec- 
tricity, therefore,  is  only  one  among  several  physical  forces  which 
resemble  each  other  in  this  respect,  but  which  are  not  on  that 
account  to  be  regarded  as  identical. 

2d.  The  Rapidity  and  Peculiarity  of  their  Action^  by  which  the 
force  is  transmitted  almost  instantaneously  to  a  distant  pointy  without 
producing  any  visible  effect  on  the  intervening  parts, — This  is  a  very 
remarkable  and  important  character,  both  of  the  nervous  force  and 
of  electricity.  In  neither  case  is  there  any  visible  effect  produced 
on  the  nervous  or  metallic  fibre  which  acts  as  a  conducting  medium ; 
but  the  final  action  is  exerted  upon  the  substances  or  organs  with 
which  it  is  in  connection.  No  definite  conclusion,  however,  can 
be  properly  derived  from  the  rapidity  of  their  transmission,  since 


AND    ITS    MODE    OF    ACTION.  337 

this  rapidity  has  never  been  accurately  measured  in  either  instance. 
We  know  that  light  and  sound  both  travel  with  much  greater 
rapidity  than  most  other  physical  forces,  and  that  electricity  is  more 
rapid  in  its  transmission  than  either ;  but  there  is  no  evidence  that 
the  velocity  of  the  latter  and  that  of  the  nervous  force  are  the  same. 
We  can  only  say  that  in  both  instances  the  velocity  is  very  great, 
without  being  able  to  compare  them  together  with  any  degree  of 
accuracy.  The  mode  of  transmission,  moreover,  alluded  to  above, 
is  not  peculiar  to  the  two  forces  which  are  supposed  to  be  identical. 
Light,  for  example,  is  transmitted  like  them  through  conducting 
media,  without  producing  in  its  passage  any  sensible  effect  until  it 
meets  with  a  body  capable  of  reflecting  it.  In  the  interval,  there- 
fore, between  the  luminous  body  and  the  reflecting  one,  there  is 
the  same  apparent  want  of  action  as  in  the  nerve,  between  the  point 
at  which  the  irritation  is  applied  and  its  termination  in  the  mus- 
cular tissue. 

3d.  The  extreme  Sensibility  of  Nerves  to  the  Electric  Current. — It 
has  already  been  mentioned  that  the  electric  current  is  the  most 
delicate  of  all  the  means  of  irritation  that  may  be  applied  to  the 
nerve  after  death ;  and  that  it  may  be  used  with  less  deleterious 
effect  than  any  other.  The  evident  reason  for  this,  however,  has 
already  been  given.  Electricity  is  one  among  several  physical 
agents  by  which  the  nerve  may  be  artificially  excited  after  death. 
It  is  less  destructive  to  the  nervous  texture  than  any  other,  and 
consequently  exhausts  its  vitality  less  rapidly.  All  these  agents 
vary  in  the  delicacy  of  their  operation;  and  though  the  electric 
current  happens  to  be  the  most  efficient  of  all,  it  is  still  simply  an 
artificial  irritant,  like  the  rest,  capable  of  imitating,  in  its  own  way, 
the  natural  stimulus  of  the  nerve. 

4th.  The  Phenomena  of  Electrical  Fishes. — It  has  been  fully  demon- 
strated that  certain  fish  (gymnotus  and  torpedo)  have  the  power  of 
generating  electricity,  and  of  producing  electric  discharges,  which 
are  often  sufficiently  powerful  to  kill  small  animals  that  may  come 
within  their  reach.  That  the  force  generated  by  these  animals  is 
in  reality  electricity,  is  beyond  a  doubt.  It  is  conducted  by  the 
same  bodies  which  serve  as  conductors  for  electricity,  and  is  stopped 
by  those  which  are  non-conductors  of  the  same.  All  the  ordinary 
phenomena  produced  by  the  electric  current,  viz :  the  heating  and 
melting  of  a  fine  conducting  wire,  the  induction  of  secondary 
currents  and  of  magnetism,  the  decomposition  of  saline  solutions, 
and  even  the  electric  spark,  have  all  been  produced  by  the  force 
22 


33S  OF    NERVOUS    IRRITABILITY 

generated  by  these  animals.  There  is  accordingly,  no  room  for 
doubt  as  to  its  nature. 

This  fact,  however,  is  very  far  from  demonstrating  the  electric 
character  of  the  nervous  force  in  general.  It  is,  on  the  contrary, 
directly  opposed  to  such  a  supposition ;  since  the  gymnotus  and 
torpedo  are  capable  of  generating  electricity  simply  because  they 
have  a  special  organ  destined  for  this  purpose.  This  organ,  which  is 
termed  the  "  electrical  organ,"  is  peculiar  to  these  fish,  and  where 
it  is  absent,  the  power  of  generating  electricity  is  absent  also.  The 
electrical  organs  of  the  gymnotus  and  torpedo  occupy  a  considerable 
portion  of  the  body,  and  are  largely  supplied  with  nerves  which 
regulate  their  function.  If  these  nerves  be  divided,  tied,  or  injured 
in  any  way,  the  electrical  organ  is  weakened  or  paralyzed,  just  as 
the  muscles  would  be  if  the  nerves  distributed  to  them  were  sub- 
jected to  a  similar  violence.  The  electricity  produced  by  these 
animals  is  not  supplied  by  the  nerves,  but  by  a  special  generating 
organ,  the  action  of  which  is  regulated  by  nervous  influence. 

The  reasons  quoted  above,  therefore,  are  quite  insufficient  for 
establishing  any  relation  of  identity  between  the  nervous  force  and 
electricity.  There  are,  moreover,  certain  well  authenticated  facts 
directly  opposed  to  such  a  supposition,  the  most  important  of  which 
are  the  following : — 

The  first  is,  that  no  electrical  current  has  been  actually  found  to  exist 
in  an  irritated  nerve.  The  most  conclusive  experiments  on  this  point 
are  those  which  were  made  by  Longet  and  Matteucci,  in  company 
with  each  other,  at  the  veterinary  school  of  Alfort.^  The  galvano- 
meter employed  in  these  investigations  was  constructed  under  the 
personal  direction  of  the  experimenters,  and  was  of  extreme  delicacy. 
The  oscillating  needle  was  surrounded  by  2500  turns  of  conducting 
wire,  and  the  poles  were  each  armed  with  a  platinum  plate,  having 
an  exposed  surface  of  one  sixth  of  a  square  inch.  When  the  poles 
of  the  apparatus  had  been  repeatedly  immersed  in  spring  water,  so 
that  no  further  variation  was  produced  from  this  source,  the  instru- 
ment was  considered  as  ready  for  use.  The  sciatic  nerve  of  a  liv- 
ing horse  was  then  exposed,  and  the  poles  of  the  galvanometer 
placed  in  contact  with  it,  in  various  positions,  both  diagonally  and 
longitudinally,  and  at  various  depths  in  its  interior.  The  examina- 
tion was  continued  for  a  quarter  of  an  hour,  during  which  time  the 
painful  sensations  of  the  animal  were  testified  by  constant  strug- 
gling movements  of  the  limbs;  showing  that  both  the  motor  and 

'  Longet,  Traite  de  Physiologic.     Paris,  1850,  vol    ii.  p.  130. 


AND    ITS    MODE    OF    ACTION.  339 

sensitive  filaments  of  the  nerve  were  in  a  high  state  of  activity. 
The  conclusion,  however,  to  which  the  experimenters  were  con- 
ducted was  the  following,  viz:  that  "there  was  no  constant  and  re- 
liable evidence  of  the  existence  of  an  electric  current  in  the  nerve." 

Secondly.  The  mode  of  conduction  of  the  nervous  force  is  different 
from  that  of  electricity/.  The  latter  force,  in  order  to  exert  its  charac- 
teristic effects,  must  be  transmitted  through  isolated  conductors,  so 
arranged  as  to  form  a  complete  circuit.  No  such  circuit  has  ever 
been  shown  to  exist  in  the  nervous  system ;  and  the  nerves  them- 
selves, the  only  tissues  capable  of  conducting  the  nervous  force,  are 
not  particularly  good  conductors  of  electricity;  no  better,  for  exam- 
ple, than  the  muscles  or  the  areolar  tissue.  We  know  of  nothing, 
therefore,  which  should  prevent  an  electric  current,  passing  through 
a  nerve,  from  being  dispersed  and  lost  among  the  adjacent  tissues. 
This  is  not  the  case,  however,  with  the  natural  stimulus  conveyed 
by  the  nervous  filament. 

Moreover  the  nerve,  in  order  to  conduct  its  own  peculiar  force, 
must  be  in  a  state  of  complete  integrity.  If  a  ligature  be  applied 
to  it,  or  if  it  be  pinched  or  lacerated,  the  muscles  to  which  it  is  dis- 
tributed are  paralyzed  for  all  voluntary  motion,  and  yet  it  transmits 
the  electric  current  as  readily  as  before.  If  the  nerve  be  divided, 
and  its  divided  extremities  replaced  in  apposition  with  each  other, 
it  will  still  act  perfectly  well  as  a  conductor  of  electricity,  though 
it  is  needless  to  say  that  its  natural  function  is  at  once  destroyed. 
The  difference  in  the  mode  of  conduction  between  the  two  forces 
may  be  shown  in  a  still  more  striking  manner,  as  follows.  Let  the 
nerve  connected  with  a  frog's  leg  be  divided,  and  its  two  extremi- 
ties joined  to  each  other  by  a  piece  of  moist  cotton  thread.  If  the 
galvanic  current  be  now  passed  through  the  detached  portion  of  the 
nerve,  no  contraction  will  take  place ;  because  the  nervous  force, 
excited  in  the  detached  portion,  cannot  be  transmitted  through  the 
cotton  thread  to  the  remainder.  But  if  one  of  the  galvanic  poles 
be  applied  above,  and  the  other  below  the  point  of  division,  a  con- 
traction is  immediately  produced ;  since  the  electric  current  is 
readily  transmitted  by  the  cotton  thread,  and  excites  the  lower 
portion  of  the  nerve,  which  is  still  in  connection  with  the  muscles. 

The  nervous  force,  therefore,  while  it  has  some  points  of  resem- 
blance with  electricity,  presents  also  certain  features  of  dissimilarity 
which  are  equally  important.  It  must  be  regarded  accordingly  as 
distinct  in  its  nature  from  other  known  physical  forces,  and  as 
altogether  peculiar  to  the  nervous  tissue  in  which  it  originates. 


840  THE    SPINAL    CORD. 


CHAPTER   III. 

THE    SPINAL   CORD. 

We  have  already  seen  that  the  spinal  cord  is  a  long  ganglion, 
covered  with  longitudinal  bundles  of  nervous  filaments,  and  occu- 
pying the  cavity  of  the  spinal  canal.  It  sends  out  nerves  which 
supply  the  muscles  and  integument  of  at  least  nine-tenths  of  the 
whole  body,  viz.,  those  of  the  neck,  trunk,  and  extremities.  All 
these  parts  of  the  body  are  endowed  with  two  very  remarkable 
properties,  the  exercise  of  which  depends,  directly  or  indirectly, 
upon  the  integrity  and  activity  of  the  spinal  cord,  viz.,  the  power 
of  sensation  and  the  power  of  motion.  Both  these  properties  are 
said  to  reside  in  the  nervous  system,  because  they  are  so  readily 
influenced  by  its  condition,  and  are  so  closely  connected  with  its 
physiological  action.  "We  shall  therefore  commence  the  study  of 
the  spinal  cord  with  an  examination  of  these  two  functions,  and  of 
the  situation  which  they  occupy  in  the  nervous  system. 

/ 

DISTINCT  SEAT  OF  SENSATION  AND  MOTION  IN  THE  NERVOUS  SYSTEM. 

Sensation  and  motion  are  usually  the  first  functions  which  suffer 
by  any  injury  inflicted  on  the  nervous  system.  As  a  general  rule, 
they  are  both  suspended  or  impaired  at  the  same  time,  and  in  a 
nearly  equal  degree.  In  a  fainting  fit,  an  attack  of  apoplexy,  con- 
cussion or  compression  of  the  brain  or  spinal  cord,  or  a  wound  of 
any  kind  involving  the  nerves  or  nervous  centres,  insensibility  and 
loss  of  motion  usually  appear  simultaneously.  It  is  difficult,  there- 
fore, under  ordinary  conditions,  to  trace  out  the  separate  action  of 
these  two  functions,  or  to  ascertain  the  precise  situation  occupied 
by  each. 

This  difficulty,  however,  may  be  removed  by  examining  sepa- 
rately different  parts  of  the  nervous  system.  In  the  instances 
mentioned  above,  the  injury  which  is  inflicted  is  comparatively  an 


DISTINCT    SEAT    OF    SENSATION    AND    MOTION.  341 

extensive  one,  and  involves  at  the  same  tinne  many  adjacent  parts. 
T5ut  instances  sometimes  occur  in  which  the  two  functions,  sensa- 
tion and  motion,  are  affected  independently  of  each  other,  owing  to 
the  peculiar  character  and  situation  of  the  injury  inflicted.  Sensa- 
tion may  be  impaired  without  loss  of  motion,  and  loss  of  motion 
may  occur  without  injury  to  sensation.  In  tic  douloureux,  for 
example,  we  have  an  exceedingly  painful  affection  of  the  sensitive 
parts  of  the  face,  without  any  impairment  of  its  power  of  motion  • 
and  in  facial  paralysis  we  often  see  a  complete  loss  of  motion  affect- 
ing one  side  of  the  face,  while  the  sensibility  of  the  part  remains 
altogether  unimpaired. 

The  above  facts  first  gave  rise  to  the  belief  that  sensation  and 
motion  might  occupy  distinct  parts  of  the  nervous  system ;  since  it 
would  otherwise  be  difficult  to  understand  how  the  two  could  be 
affected  independently  of  each  other  by  anatomical  lesions.  It  has 
accordingly  been  fully  established,  by  the  labors  of  Sir  Charles  Bell, 
Miiller,  Panizza,  and  Longet,  that  the  two  functions  do  in  reality 
occupy  distinct  parts  of  the  nervous  system. 

If  any  one  of  the  spinal  nerves,  in  the  living  animal,  after  being 
exposed  at  any  part  of  its  course  outside  the  spinal  canal,  be  divided, 
ligatured,  bruised,  or  otherwise  seriously  injured,  paralysis  of  motion 
and  loss  of  sensation  are  immediately  produced  in  that  part  of  the 
body  to  which  the  nerve  is  distributed.  If,  on  the  other  hand,  the 
same  nerve  be  pricked,  galvanized,  or  otherwise  gently  irritated,  a 
painful  sensation  and  convulsive  movements  are  produced  in  the 
same  parts.  The  nerve  is  therefore  said  to  be  both  sensitive  and 
excitable;  sensitive,  because  irritation  of  its  fibres  produces  a  pain- 
ful sensation,  and  excitable,  because  the  same  irritation  causes  mus- 
cular contraction  in  the  parts  below. 

The  result  of  the  experiment,  however,  will  be  different  if  it  be 
tried  upon  the  parts  situated  inside  the  spinal  canal,  and  particularly 
upon  the  anterior  and  posterior  roots  of  the  spinal  nerves.  If  an 
irritation  be  applied,  for  example,  to  the  anterior  root  of  a  spinal 
nerve,  in  the  living  animal,  convulsive  movements  are  produced  in 
the  parts  below,  but  there  is  no  painful  sensation.  The  anterior 
root  accordingly  is  said  to  be  excitable,  but  not  sensitive.  If  the 
posterior  root,  on  the  other  hand,  be  irritated,  acute  pain  is  pro- 
duced, but  no  convulsive  movements.  The  posterior  root  is  there- 
fore sensitive,  but  not  excitable.  A  similar  result  is  obtained  by  a 
complete  division  of  the  two  roots.  Division  of  the  anterior  root 
produces  paralysis  of  motion,  but  no  insensibility ;  division  of  the 


3ri2  THE    SPINAL    CORD. 

posterior  root  produces  complete  loss  of  sensibility,  but  no  muscular 
paralysis. 

We  have  here,  then,  a  separate  localization  of  sensation  and 
motion  in  the  nervous  system ;  and  it  is  accordingly  easy  to  under- 
stand how  one  may  be  impaired  without  injury  to  the  other,  or 
how  both  may  be  simultaneously  affected,  according  to  the  situation 
and  extent  of  the  anatomical  lesion. 

The  two  roots  of  a  spinal  nerve  differ  from  each  other,  further- 
more, in  their  mode  of  transmitting  the  nervous  impulse.  If  the 
posterior  root  be  divided  (E'ig.  135)  at  «,  b,  and  an  irritation  applied 

Fig.  135. 


Diagi-am   of  SpiXAL    Cord  and  Nekves.      The  posterior  root  is  seeu  divided  at  n,  h.  tlie 
anterior  at  c,  d. 

to  the  separated  extremity  (a),  no  effect  will  be  produced ;  but  if 
the  irritation  be  applied  to  the  attached  extremity  {h\  a  painful 
sensation  is  immediately  the  result.  The  nervous  force,  therefore, 
travels  in  the  posterior  root  from  without  inward,  but  cannot  pass 
from  within  outward.  If  the  anterior  root,  on  the  other  hand,  be 
divided  at  c,  d,  and  its  attached  extremity  [d)  irritated,  no  effect 
follows ;  but  if  the  separated  extremity  (c)  be  irritated,  convulsive 
movements  instantly  take  place.  The  nervous  force,  consequently, 
travels  in  the  anterior  root  from  within  outward,  but  cannot  pass 
from  without  inward. 

The  same  thing  is  true  with  regard  to  the  transmission  of  sensa- 
tion and  motion  in  the  spinal  nerves  outside  the  spinal  canal.  If 
one  of  these  nerves  be  divided  in  the  living  animal,  and  its  attached 
extremity  irritated,  pain  is  produced,  but  no  convulsive  motion;  if 


SENSIBILITY    AND    EXCITABILITY    IN    SPINAL    CORD.      343 

the  irritation  be  applied  to  its  separated  extremity,  muscular  con- 
tractions follow,  but  no  painful  sensation. 

There  are,  therefore,  two  kinds  of  filaments  in  the  spinal  nerves, 
not  distinguishable  by  the  eye,  but  entirely  distinct  in  their  character 
and  function,  viz.,  the  "sensitive"  filaments,  or  those  which  convey 
sensation,  and  the  "  motor"  filaments,  or  those  which  excite  move- 
ment. These  filaments  are  never  confounded  with  each  other  in 
their  action,  nor  can  they  perform  each  other's  functions.  The  sen- 
sitive filaments  convey  the  nervous  force  only  in  a  centripetal,  the 
motor  only  in  a  centrifugal  direction,  The  former  preside  over 
sensation,  and  have  nothing  to  do  with  motion ;  the  latter  preside 
over  motion,  and  have  nothing  to  do  with  sensation.  Within  the 
spinal  canal  the  two  kinds  of  filaments  are  separated  from  each 
other,  constituting  the  anterior  and  posterior  roots  of  each  spinal 
nerve;  but  externally  they  are  mingled  together  in  a  common 
trunk.  While  the  anterior  and  posterior  roots,  therefore,  are  ex- 
clusively sensitive  or  exclusively  motor,  the  spinal  nerves  beyond 
the  junction  of  the  roots  are  called  mixed  nerves^  because  they  con- 
tain at  the  same  time  motor  and  sensitive  filaments.  The  mixed 
nerves  accordingly  preside  at  the  same  time  over  the  functions  of 
movement  and  of  sensation. 


DISTINCT   SEAT  OF   SENSIBILITY  AND   EXCITABILITY  IN  THE   SPINAL 

CORD. 

Various  experimenters  have  demonstrated  the  fact  that  different 
])arts  of  the  spinal  cord,  like  the  two  roots  of  the  spinal  nerves,  are 
separately  endowed  with  sensibility  and  excitability.  The  anterior 
columns  of  the  cord,  like  the  anterior  roots  of  the  spinal  nerves, 
are  excitable  but  not  sensitive ;  the  posterior  columns,  like  the 
posterior  roots  of  the  spinal  nerves,  are  sensitive  but  not  excitable. 
Accordingly,  when  the  spinal  canal  is  opened  in  the  living  animal, 
an  irritation  applied  to  the  anterior  columns  of  the  cord  produces 
immediately  convulsions  in  the  limbs  below ;  but  there  is  no  indi- 
cation of  pain.  On  the  other  hand,  signs  of  acute  pain  become 
manifest  whenever  the  irritation  is  applied  to  the  posterior  column ; 
but  no  muscular  contractions  follow,  other  than  those  of  a  voluntary 
character.  Longet  has  found'that  if  the  spinal  cord  be  exposed  in 
the  lumbar  region  and  completely  divided  at  that  part  by  trans- 

'  Traite  de  Physiologie,  voL  ii.  part  2,  p.  8. 


344  THE    SPINAL    COED. 

verse  section,  the  application  of  any  irritant  to  tbe  anterior  surface 
of  the  separated  portion  produces  at  once  convulsions  below  ;  while 
if  applied  to  the  posterior  columns  behind  the  point  of  division,  it 
has  no  sensible  effect  whatever.  The  anterior  and  posterior  columns 
of  the  cord  are  accordingly,  so  far,  analogous  in  their  properties  to 
the  anterior  and  posterior  roots  of  the  spinal  nerves,  and  are  plainly 
composed,  to  a  greater  or  less  extent,  of  a  continuation  of  their 
filaments. 

These  filaments,  derived  from  the  anterior  and  posterior  roots 
of  the  spinal  nerves,  pass  upward  through  the  spinal  cord  toward 
the  brain.  An  irritation  applied  to  any  part  of  the  integument 
is  then  conveyed,  along  the  sensitive  filaments  of  the  nerve  and 
its  posterior  root,  to  the  spinal  cord;  then  upward,  along  the 
longitudinal  fibres  of  the  cord  to  the  brain,  where  it  produces  a 
sensation  corresponding  in  character  with  the  original  irritation. 
A  motor  impulse,  on  the  other  hand,  originating  in  the  brain,  is 
transmitted  downward,  along  the  longitudinal  fibres  of  the  cord, 
passes  outward  by  the  anterior  root  of  the  spinal  nerve,  and  follow- 
ing the  motor  filaments  of  the  nerve  through  its  trunk  and  branches, 
produces  at  last  a  muscular  contraction  at  the  point  of  its  final 
distribution. 


CEOSSED  ACTION  OF  THE  SPINAL  COED. 

As  the  anterior  columns  of  the  cord  pass  upward  to  join  the 
medulla  oblongata,  a  decussation  takes  place  between  them,  as  we 
have  already  mentioned  in  Chapter  I.  The  fibres  of  the  right 
anterior  column  pass  over  to  the  left  side  of  the  medulla  oblongata, 
and  so  upward  to  the  left  side  of  the  brain ;  while  the  fibres  of  the 
left  anterior  column  pass  over  to  the  right  side  of  the  medulla 
oblongata,  and  so  upward  to  the  right  side  of  the  brain.  This 
decussation  may  be  readily  shown  (as  in  Fig.  130)  by  gently 
separating  the  anterior  columns  from  each  other,  at  the  lower  ex- 
tremity of  the  medulla  oblongata,  where  the  decussating  bundles 
may  be  seen  crossing  obliquely  from  side  to  side,  at  the  bottom  of 
the  anterior  median  fissure.  Below  this  point,  the  anterior  columns 
remain  distinct  from  each  other  on  each  side,  and  do  not  communi- 
cate by  any  further  decussation. 

If  the  anterior  columns  of  the  spinal  cord,  therefore,  be  wounded 
at  any  point  in  the  cervical,  dorsal,  or  lumbar  region,  a  paralysis 


CROSSED    ACTION    OF    THE    SPINAL    CORD.  345 

of  voluntary  motion  is  produced  in  the  limbs  below,  on  the  same 
side  with  the  injury.  But  if  a  similar  lesion  occur  in  the  brain, 
the  paralysis  which  results  is  on  the  opposite  side  of  the  body. 
Thus  it  has  long  been  known  that  an  abscess  or  an  apoplectic 
hemorrhage  on  the  right  side  of  the  brain  will  produce  paralysis 
of  the  left  side  of  the  body;  and  injury  of  the  left  side  of  the 
brain  will  be  followed  by  paralysis  of  the  right  side  of  the  body. 

The  spinal  cord  has  also  a  crossed  action  in  transmitting  sensi- 
tive as  well  as  motor  impulses.  It  has  been  recently  demonstrated 
by  Dr.  Brown-Sdquard,'  that  the  crossing  of  the  sensitive  fibres  in 
the  spinal  cord  does  not  take  place,  like  that  of  the  motor  fibres, 
at  its  upper  portion  only,  but  throughout  its  entire  length ;  so  that 
the  sensitive  fibres  of  the  right  spinal  nerves,  very  soon  after  their 
entrance  into  the  cord,  pass  over  to  the  left  side,  and  those  of  the 
left  spinal  nerves  pass  over  to  the  right  side.  For  if  one  lateral 
half  of  the  spinal  cord  of  a  dog  be  divided  in  the  dorsal  region, 
the  power  of  sensation  remains  upon  the  corresponding  side  of  the 
body,  but  is  lost  upon  the  opposite  side.  It  has  been  shown,  fur- 
thermore, by  the  same  observer,^  that  the  sensitive  fibres  of  the 
spinal  nerves,  when  they  first  enter  the  cord  join  the  posterior 
columns,  which  are  everywhere  extremely  sensitive ;  but  that  they 
very  soon  leave  the  posterior  columns,  and,  passing  through  the 
central  parts  of  the  cord,  run  upward  to  the  opposite  side  of  the 
brain.  If  the  posterior  columns,  accordingly,  be  alone  divided  at 
any  part  of  the  spinal  cord,  sensibility  is  not  destroyed  in  all  the 
nerves  behind  the  seat  of  injury,  but  only  in  those  which  enter  the 
cord  at  the  point  of  section ;  since  the  posterior  columns  consist 
of  different  nervous  filaments,  joining  them  constantly  on  one  side 
from  below,  and  leaving  them  on  the  other  to  pass  upward  toward 
the  brain.  """"^ 

The  spinal  cord  has  therefore  a  crossed  action,  both  for  sensa- 
tion and  motion ;  but  the  crossing  of  the  motor  filaments  occurs 
only  at  the  medulla  oblongata,  while  that  of  the  sensitive  filaments 
takes  place  throughout  the  entire  length  of  the  cord  itself. 

There  are  certain  important  facts  which  still  remain  to  be  noticed, 
regarding  the  mode  of  action  of  the  spinal  cord  and  its  nerves. 
They  are  as  follows : — 

'  Experimental  Researches  applied  to  Physiology  and  Pathology.  New  York, 
1853. 

2  Memoirs  sur  la  Physiologie  de  la  Moelle  epiniere  ;  Gazette  Medicale  de  Paris, 
1855. 


3.46  THE    SPINAL    CORD. 

1.  An  {rrilation  a2'>plied  to  a  spinal  nerve  at  the  middle  of  its  course 
"produces  the  same  effect  as  if  it  traversed  its  entire  length.  Thus,  if  the 
sciatic  or  median  nerve  be  irritated  at  any  part  of  its  course,  con- 
traction is  produced  in  the  muscles  to  which  these  nerves  are  dis- 
tributed, just  as  if  the  impulse  had  originated  as  usual  from  the 
brain.  This  fact  depends  upon  the  character  of  the  nervous  fila- 
ments, as  simple  conductors.  Wherever  the  impulse  may  originate, 
the  final  effect  is  manifested  only  at  the  termination  of  the  nerve. 
As  the  impulse  in  the  motor  nerves  travels  always  in  an  outward 
direction,  the  effect  is  always  produced  at  the  muscular  termination 
of  the  filaments,  no  matter  how  small  or  how  large  a  portion  of 
their  length  may  have  been  engaged  in  transmitting  the  stimulus. 

If  the  irritation,  again,  be  applied  to  a  sensitive  nerve  in  the 
middle  of  its  course,  the  painful  sensation  is  felt,  not  at  the  point 
of  the  nerve  directly  irritated,  but  in  that  portion  of  the  integu- 
ment to  which  its  filaments  are  distributed.  Thus,  if  the  ulnar 
nerve  be  accidentally  struck  at  the  point  where  it  lies  behind  the 
inner  condyle  of  the  humerus,  a  sensation  of  tingling  and  numb- 
ness is  produced  in  the  last  two  fingers  of  the  corresponding  hand. 
It  is  common  to  hear  patients  who  have  suffered  amputation  com- 
plain of  painful  sensations  in  the  amputated  limb,  for  weeks  or 
months,  and  sometimes  even  for  years  after  the  operation.  They 
assert  that  they  can  feel  the  separated  parts  as  distinctly  as  if  they 
were  still  attached  to  the  body.  This  sensation,  which  is  a  real 
one  and  not  fictitious,  is  owing  to  some  irritation  operating  upon 
the  divided  extremities  of  the  nerves  in  the  cicatrized  wound.  Such 
an  irritation,  conveyed  to  the  brain  by  the  sensitive  fibres,  will  pro- 
duce precisely  the  same  sensation  as  if  the  amputated  parts  were 
still  present,  and  the  irritation  actually  applied  to  them. 

It  is  on  this  account  also  that  division  of  the  trifacial  nerve  is 
not  always  effectual  in  the  cure  of  tic  douloureux.  If  the  cause  of 
the  difficulty  be  seated  upon  the  trunk  of  the  nerve,  between  its 
point  of  emergence  from  the  bones  and  its  origin  in  the  brain,  it  is 
evident  that  division  of  the  nerve  upon  the  face  will  be  of  no 
avail;  since  the  cause  of  irritation  will  still  exist  behind  the  point 
of  section,  and  the  same  painful  sensations  will  still  be  produced  in 
the  brain. 

2.  The  irritability  of  the  motor  filaments  disapjyears  from  within  oiit- 
ward,  that  of  the  sensitive  filaments  from  without  inward.  Immedi- 
ately after  the  separation  of  the  frog's  leg  from  the  body,  irritation 
of  the  nerve  at  any  point  produces  muscular  contraction  in  the 


INDEPENDENCE    OF    NEEVOUS    FILAMENTS.  347 

limb  below.  As  time  elapses,  however,  and  the  irritability  of  the 
nerve  diminishes,  the  galvanic  current,  in  order  to  produce  con- 
traction, must  be  applied  at  a  point  nearer  its  termination.  Subse- 
quently, the  irritability  of  the  nerve  is  entirely  lost  in  its  upper 
portions,  but  is  retained  in  the  parts  situated  lower  down,  from 
which  it  also,  in  turn,  afterward  disappears;  receding  in  this  man- 
ner farther  and  farther  toward  the  terminal  distribution  of  the 
nerve,  where  it  finally  disappears  altogether. 

On  the  other  hand,  sensibility  disappears,  at  the  time  of  death, 
first  in  the  extremities.  From  them  the  numbness  gradually  creeps 
upward,  invading  successively  the  middle  and  upper  portions  of  the 
limbs,  and  the  more  distant  portions  of  the  trunk.  The  central 
parts  are  the  last  to  become  insensible. 

3.  Each  nervous  filament  acts  independently  of  the  rest  throughout  its 
entire  lengthy  and  does  not  communicate  its  irritation  to  those  which  are 
in  proximity  with  it.  It  is  evident  that  this  is  true  with  regard  to 
the  nerves  of  sensation,  from  the  fact  that  if  the  integument  be 
touched  with  the  point  of  a  needle,  the  sensation  is  referred  to  that 
spot  alone.  Since  the  nervous  filaments  coming  from  it  and  the 
adjacent  parts  are  all  bound  together  in  parallel  bundles,  to  form 
the  trunk  of  the  nerve,  if  any  irritation  were  communicated  from 
one  sensitive  filament  to  another,  the  sensation  produced  would  be 
indefinite  and  diffused,  whereas  it  is  really  confined  to  the  spot  irri- 
tated. If  a  frog's  leg,  furthermore,  be  prepared,  with  the  sciatic 
nerve  attached,  a  few  of  the  fibres  separated  laterally  from  the 
nervous  trunk  for  a  portion  of  its  length,  and  the  poles  of  a  galvanic 
battery  applied  to  the  separated  portion,  the  contractions  which 
follow  in  the  leg  will  not  be  general,  but  will  be  confined  to  those 
muscles  in  which  the  galvanized  nervous  fibres  especially  have 
their  distribution.  There  are  also  various  instances,  in  the  body, 
of  antagonistic  muscles,  which  must  act  independently  of  each 
other,  but  which  are  supplied  with  nerves  from  a  common  trunk. 
The  superior  and  inferior  straight  muscles  of  the  eyeball,  for 
example,  are  both  supplied  by  the  motor  oculi  communis  nerve. 
Extensor  and  flexor  muscles,  as,  for  example,  those  of  the  fingers, 
are  often  supplied  by  the  same  nerve,  and  yet  act  alternately  with- 
out mutual  interference.  It  is  easy  to  see  that  if  this  were  not  the 
case,  confusion  would  constantly  arise,  both  in  the  perception  of 
sensations,  and  in  the  execution  of  movements, 

4.  There  are  certain  sensations  which  are  excited  simultaneously 
by  the  same  causes,  and  which  are  termed  associated  sensations ;  and 


348  THE    SPINAL    COED. 

there  are  also  certain  movements  which  take  place  simultaneously, 
and  are  called  associated  movements.  In  the  former  instance,  one  of 
the  associated  sensations  is  called  up  immediately  upon  the  percep- 
tion of  the  other,  without  requiring  any  direct  impulse  of  its  own. 
Thus,  tickling  the  soles  of  the  feet  produces  a  peculiar  sensation 
at  the  epigastrium.  Nausea  is  occasioned  by  certain  disagreeable 
odors,  or  by  rapid  rotation  of  the  body,  so  that  the  landscape  seems 
to  turn  round.  A  striking  example  of  associated  movements,  on 
the  other  hand,  may  be  found  in  the  action  of  the  muscles  of  the 
eyeball.  The  eyeballs  always  accompany  each  other  in  their  lateral 
motions,  turning  to  the  right  or  the  left  side  simultaneously.  It  is 
evident,  however,  that  in  producing  this  correspondence  of  motion, 
the  left  internal  rectus  muscle  must  contract  and  relax  together 
with  the  right  external;  while  a  similar  harmony  of  action  must 
exist  between  the  right  internal  and  the  left  external.  The  explana- 
tion of  such  singular  correspondences  cannot  be  found  in  the  anato- 
mical arrangement  of  the  muscles  themselves,  nor  in  that  of  the 
nervous  filaments  by  which  they  are  directly  supplied,  but  must  be 
looked  for  in  some  special  endowment  of  the  nervous  centres  from 
which  they  originate. 


EEFLEX  ACTION  OF  THE  SPINAL  CORD. 

The  spinal  cord,  as  we  have  thus  far  examined  it,  may  be  re- 
garded simply  as  a  great  nerve  ;  that  is,  as  a  bundle  of  motor  and 
sensitive  filaments,  connecting  the  muscles  and  integument  below 
with  the  brain  above,  and  assisting,  in  this  capacity,  in  the  produc- 
tion of  conscious  sensation  and  voluntary  motion.  Beside  its  nerv- 
ous filaments,  however,  it  contains  also  a  large  quantity  of  gray 
matter,  and  is,  therefore,  itself  a  ganglionic  centre,  and  capable  of 
independent  action  as  such.  We  shall  now  proceed  to  study  it  in 
its  second  capacity,  as  a  distinct  nervous  centre. 

If  a  frog  be  decapitated,  and  the  body  allowed  to  remain  at  rest 
for  a  few  moments,  so  as  to  recover  from  the  depressing  effects  of 
shock  upon  the  nervous  system,  it  will  be  found  that,  although  sen- 
sation and  consciousness  are  destroyed,  the  power  of  motion  still 
remains.  If  the  skin  of  one  of  the  feet  be  irritated  by  pinching  it 
with  a  pair  of  forceps,  the  leg  is  immediately  drawn  up  toward  the 
body,  as  if  to  escape  the  cause  of  irritation.  If  the  irritation  applied 
to  the  foot  be  of  slight  intensity,  the  corresponding  leg  only  will 


KEFLEX    ACTION    OF    THE    SPINAL    CORD. 


349 


move;  but  if  it  be  more  severe  in  character,  motions  will  often  be 
produced  in  the  posterior  extremity  of  the  opposite  side,  and  even 
in  the  two  fore-legs,  at  the  same  time.  These  motions,  it  is  import- 
ant to  observe,  are  never  spontaneous.  The  decapitated  frog  remains 
perfectly  quiescent  if  left  to  himself.  It  is  only  when  some  cause 
of  irritation  is  applied  externally,  that  movements  occur  as  above 
described. 

It  will  be  seen  that  the  character  of  these  phenomena  indicates 
the  active  operation  of  some  part  of  the  nervous  system,  and  par- 
ticularly of  some  ganglionic  centre.  The  irritation  is  applied  to 
the  skin  of  the  foot,  and  the  muscles  of  the  leg  contract  in  conse- 
quence; showing  evidently  the  intermediate  action  of  a  nervous 
connection  between  the  two. 

The  effect  in  question  is  due  to  the  activity  of  the  spinal  cord, 
operating  as  a  nervous  centre.     In  order  that  the  movements  may 
take  place  as  above,  it  is  essential  that  both  the  integument  and  the 
muscles  should  be  in  communication  with  the  spinal  cord  by  nerv- 
ous filaments,  and  that  the  cord  itself  be  in  a  state  of  integrity.     If 
the  sciatic  nerve  be  divided  in  the  upper  part  of  the  thigh,  irrita- 
tion of  the  skin  below  is  no  longer  followed  by  any  muscular  con- 
traction.    If  either  the  anterior  or  posterior  roots  of  the  nerve  be 
divided,  the  same  want  of  action  results;  and  finally,  if,  the  nerve 
and  its  roots  remaining  entire,  the  spinal  cord  itself  be  broken  up 
by  a  needle  introduced  into  the  spinal 
canal,  the   integument   may  then  be 
irritated  or  mutilated  to  any  extent, 
without  exciting   the  least  muscular 
contraction.     It  is  evident,  therefore, 
that  the  spinal  cord  acts,  in  this  case, 
as  a  nervous  centre,  through  which 
the  irritation  applied  to  the  skin  is 
communicated  to  the  muscles.     The 
irritation  first  passes  upward,  as  shown 
in  the   accompanying  diagram  (Fig. 
136),  along  the  sensitive  fibres  of  the 
posterior  root  (a)  to  the  gray  matter 
of  the  cord,  and  is  then  reflected  back, 
along  the  motor  fibres  of  the  anterior 
root,  until  it  finally  reaches  the  mus- 
cles, and  produces  a  contraction.     This  action  is  known,  accord 
ingly,  as  the  reflex  action  of  the  spinal  cord. 


Fig.  136. 


Diagram  of  Spinal  Cord  in  Ver- 
tical Section,  showing  reflex  action. 
— a  Posterior  root  of  spinal  nerve.  6.  An- 
terior root  of  spinal  nerve. 


350  THE    SPIXAL    CORD. 

It  will  be  remembered  that  this  reflex  action  of  the  cord  is  not 
accompanied  by  any  volition,  nor  even  by  any  conscious  sensation. 
The  function  of  the  spinal  cord  as  a  nervous  centre  is  simply  to 
convert  an  impression,  received  from  the  skin,  into  a  motor  impulse 
which  is  sent  out  again  to  the  muscles.  There  is  absolutely  no 
farther  action  than  this ;  no  exercise  of  will,  consciousness,  or  judg- 
ment. This  action  will  therefore  take  place  perfectly  well  after 
the  brain  has  been  removed,  and  after  the  entire  sympathetic  sys- 
tem has  also  been  taken  away,  provided  only  that  the  spinal  cord 
and  its  nerves  remain  in  a  state  of  integrity. 

The  existence  of  this  reflex  action  after  death  is  accordingly  an 
evidence  of  the  continued  activity  of  the  spinal  cord,  just  as  con- 
tractility is  an  evidence  of  the  activity  of  the  muscles,  and  irrita- 
bility of  that  of  the  nerves.  Like  the  two  last-mentioned  properties, 
also,  it  continues  for  a  longer  time  after  death  in  cold-blooded  than 
in  warm-blooded  animals.  It  is  for  this  reason  that  frogs  and  other 
reptiles  are  the  most  useful  subjects  for  the  study  of  these  pheno- 
mena, as  for  that  of  most  others  belonging  to  the  nervous  system. 

The  irritability  of  the  spinal  cord,  as  manifested  by  its  reflex 
action,  may  be  very  much  exaggerated  by  certain  diseases,  and  by 
the  operation  of  poisonous  substances.  Tetanus  and  poisoning  b}^ 
strychnine  both  act  in  this  way,  by  heightening  the  irritability  of 
the  spinal  cord,  and  causing  it  to  produce  convulsive  movements 
on  the  application  of  external  stimulus.  It  has  been  observed  that 
the  convulsions  in  tetanus  are  rarely,  if  ever,  spontaneous,  but  that 
they  always  require  to  be  excited  by  some  external  cause,  such  as 
the  accidental  movement  of  the  bedclothes,  the  shutting  of  a  door, 
or  the  sudden  passage  of  a  current  of  air.  Such  slight  causes  of 
irritation,  which  would  be  entirely  inadequate  to  excite  involuntary 
movements  in  the  healthy  condition,  act  upon  the  spinal  cord,  when 
its  irritability  is  heightened  by  disease,  in  such  a  manner  as  to  pro- 
duce violent  convulsions. 

Similar  appearances  are  to  be  seen  in  animals  poisoned  by  strych- 
nine. This  substance  acts  upon  the  spinal  cord  and  increases  its 
irritability,  without  materially  affecting  the  functions  of  the  brain. 
Its  effects  will  show  themselves,  consequently,  without  essential 
modification,  after  the  head  has  been  removed.  If  a  decapitated 
frocr  be  poisoned  with  a  moderate  dose  of  strychnine,  the  body  and 
limbs  will  remain  quiescent  so  long  as  there  is  no  external  source 
of  excitement;  but  the  limbs  are  at  once  thrown  into  convulsions 
by  the  slightest  irritation  applied  to  the  skin,  as,  for  example,  the 


KEFLEX    ACTION    OF    THE    SPINAL    CORD.  351 

contact  of  a  hair  or  a  feather,  or  even  the  jarring  of  the  table  on 
which  the  animal  is  placed.  That  the  convulsions  in  cases  of 
poisoning  by  strychnine  are  always  of  a  reflex  character,  and  never 
spontaneous,  is  shown  by  the  following  fact  first  noticed  by  Bernard,' 
viz.,  that  if  a  frog  be  poisoned  after  division  of  the  posterior  roots 
of  all  the  spinal  nerves,  while  the  anterior  roots  are  left  untouched, 
death  takes  place  as  usual  but  is  not  preceded  by  any  convulsions. 
In  this  instance  the  convulsions  are  absent  simply  because,  owing 
to  the  division  of  the  posterior  roots,  external  irritations  cannot  be 
communicated  to  the  cord. 

The  reflex  action,  above  described,  may  be  seen  very  distinctly 
in  the  human  subject,  in  certain  cases  of  disease  of  the  spinal  cord. 
If  the  upper  portion  of  the  cord  be  disintegrated  by  inflammatory 
softening,  so  that  its  middle  and  lower  portions  lose  their  natural 
connection  with  the  brain,  paralysis  of  voluntary  motion  and  loss 
of  sensation  ensue  in  all  parts  of  the  body  below  the  seat  of  the 
anatomical  lesion.  Under  these  conditions,  the  patient  is  incapable 
of  making  any  muscular  exertion  in  the  paralyzed  parts,  and  is 
unconscious  of  any  injury  done  to  the  integument  in  the  same 
region.  Notwithstanding  this,  if  the  soles  of  the  feet  be  gently 
irritated  with  a  feather,  or  with  the  point  of  a  needle,  a  convulsive 
twitching  of  the  toes  will  often  take  place,  and  even  retractile  move- 
ments of  the  leg  and  thigh,  altogether  without  the  patient's  know- 
ledge. Such  movements  may  frequently  be  excited  by  simply 
allowing  the  cool  air  to  come  suddenly  in  contact  with  the  lower 
extremities.  We  have  repeatedly  witnessed  these  phenomena,  in 
a  case  of  disease  of  the  spinal  cord  where  the  paralysis  and  in- 
sensibility of  the  lower  extremities  were  complete.  Many  other 
similar  instances  are  reported  by  various  authors^ 

The  existence  of  this  reflex  action  of  the  cord  has  enabled  the 
physiologist  to  ascertain  several  other  important  facts  concerning 
the  mode  of  operation  of  the  nervous  system.  M,  Bernard  has 
demonstrated,^  by  a  series  of  extremely  ingenious  experiments  on 
the  action  of  poisonous  substances,  1st,  that  the  irritability  of  the 
muscles  may  be  destroyed,  while  that  of  the  nerves  remains  unal- 
tered ;  and  2d,  that  the  motor  and  sensitive  nervous  filaments  may 
each  be  paralyzed  independently  of  each  other.  The  above  facts 
are  shown  by  the  three  following  experiments: — 

'  Lecjons  sur  les  eflFets  des  Substances  toxiques  et  medicamenteuses,  Paris,  1857, 
p.  357. 

^  Lecjons  sur  le.s  effets  des  Substances  toxiques  et  nielicanienteuses,  Chaps.  23 
and  24. 


352 


THE    SPIXAL    COBD. 


1.  In  a  living  frog  (Fig.  137),  the  sciatic  nerve  (xV)  is  exposed  in  the 
back  part  of  the  thigh,  after  which  a  ligature  is  passed  underneath 

it  and  drawn  tight  around  the 
^^"  bone  and  the  remaining  soft 

parts.  In  this  way  the  circu- 
lation is  entirely  cut  off"  from 
the  limb  {d)^  which  remains 
in  connection  with  the  trunk 
only  by  means  of  the  sciatic 
nerve.  A  solution  of  sulpho- 
cyanide  of  potassium  is  then 
introduced  beneath  the  skin 
of  the  back,  at  /,  in  sufficient 
quantity  to  produce  its  speci- 
fic effect.  The  poison  is  then 
absorbed,  and  is  carried  by 
the  circulation  throughout  the 
trunk  and  the  three  extremi- 
ties a,  6,  c;  while  it  is  prevented 
from  entering  the  limb  c?,  by 
the  ligature  which  has  been 
placed  about  the  thigh.  Sul- 
phocyanide  of  potassium  pro- 
duces paralysis,  as  we  have 
previously  mentioned,  by  act- 
ing directly  upon  the  muscu- 
lar tissue.  Accordingly,  a  gal- 
vanic discharge  passed  through 
the  limbs  a,  5,  and  c,  produces 
no  contraction  in  them,  while 
the  same  stimulus,  applied  to 
d,  is  follow^ed  by  a  strong  and  healthy  reaction.  But  at  the  moment 
when  the  irritation  is  applied  to  the  poisoned  limbs  a,  h,  and  c, 
though  no  visible  effect  is  produced  in  them,  an  active  movement 
takes  place  in  the  healthy  limb,  d.  This  can  only  be  owing  to  a 
reflex  action  of  the  spinal  cord,  originating  in  the  integument  of  a, 
6,  and  c,  and  transmitted,  by  sensitive  and  motor  filaments,  through 
the  cord,  to  d.  While  the  muscles  of  the  poisoned  limbs,  therefore,  have 
been  directly  paralyzed,  the  nerves  of  the  same  parts  have  retained  their 
irritability. 

2.  If  a  frog  be  poisoned  with  woorara  by  simply  placing  the 


REFLEX    ACTION    OF    THE    SPINAL    CORD.  353 

poison  under  the  skin,  no  reflex  action  of  the  spinal  cord  can  be 
demonstrated  after  death.  We  have  already  shown,  from  experi- 
ments detailed  in  Chapter  II.,  that  this  substance  destroys  the  irrita- 
bility of  the  motor  nerves,  without  affecting  that  of  the  muscles.  In 
the  above  instance,  therefore,  where  the  reflex  action  is  abolished,  its 
loss  may  be  owing  to  a  paralysis  of  both  motor  and  sensitive  fila- 
ments, or  to  that  of  the  motor  filaments  alone.  The  following  experi- 
ment, however,  shows  that  the  motor  filaments  are  the  only  ones 
affected.  If  a  frog  be  prepared  as  in  Fig.  137,  and  poisoned  by  the 
introduction  of  woorara  at  /,  when  the  limb  d  is  irritated  its  own 
muscles  react,  while  no  movement  takes  place  in  a,  5,  or  c;  but  if 
the  irritation  be  applied  to  a,  &,  or  c,  reflex  movements  are  imme- 
diately produced  in  d.  In  the  poisoned  limbs,  there/ore,  while  the 
motor  nerves  have  been  paralyzed,  the  sensitive  filaments  have  retained 
their  irritability. 

3.  If  a  frog  be  poisoned  with  strychnine,  introduced  underneath 
the  skin  in  sufficient  quantity,  death  takes  place  after  general  con- 
vulsions, which  are  due,  as  we  have  seen  above,  to  an  unnatural 
excitability  of  the  reflex  action.  This  is  followed,  however,  by  a 
paralysis  of  sensibility,  so  that  after  death  no  reflex  movements 
can  be  produced  by  irritating  the  skin  or  even  the  posterior  roots 
of  the  spinal  nerves.  But  if  the  anterior  roots,  or  the  motor  nerves 
themselves  be  galvanized,  contractions  immediately  take  place  in 
the  corresponding  muscles.  In  this  case,  therefore,  the  sensitive  fila- 
ments have  been  paralyzed,  while  the  motor  filaments  and  the  muscles 
have  retained  their  irritability. 

We  come  now  to  investigate  the  reflex  action  of  the  spinal  cord, 
as  it  takes  place  in  a  healthy  condition  during  life.  This  action 
readily  escapes  notice,  unless  our  attention  be  particularly  directed 
to  it,  because  the  sensations  which  we  are  constantly  receiving,  and 
the  many  voluntary  movements  which  are  continually  executed, 
serve  naturally  to  mask  those  nervous  phenomena  which  take  place 
without  our  immediate  knowledge,  and  over  which  we  exert  no 
voluntary  control.  Such  phenomena,  however,  do  constantly  take 
place,  and  are  of  extreme  physiological  importance.  If  the  surface 
of  the  skin,  for  example,  be  at  any  time  unexpectedly  brought  in 
contact  with  a  heated  body,  the  injured  part  is  often  withdrawn  by 
a  rapid  and  convulsive  movement,  long  before  we  feel  the  pain,  or 
even  understand  fairly  the  cause  of  the  involuntary  act.  If  the 
body,  by  any  accident,  suddenly  and  unexpectedly  lose  its  balance, 
the  limbs  are  thrown  into  a  position  calculated  to  protect  the  ex- 
23 


354  THE    SPIXAL    CORD. 

posed  parts  and  to  break  the  fall,  by  a  similar  involuntary  and  in- 
stantaneous movement.  The  brain  does  not  act  in  these  cases,  for 
there  is  no  intentional  character  in  the  movement,  nor  even  any 
complete  consciousness  of  its  object.  Everything  indicates  that  it 
is  the  immediate  result  of  a  simple  reflex  action  of  the  spinal  cord. 

The  cord  exerts  also  an  important  and  constant  influence  upon 
the  sphincter  muscles.  The  sphincter  ani  is  habitually  in  a  state  of 
contraction,  so  that  the  contents  of  the  intestine  are  not  allowed  to 
escape.  When  any  external  irritation  is  applied  to  the  anus,  or 
whenever  the  feces  present  themselves  internally,  the  sphincter 
contracts  involuntarily,  and  the  discharge  of  the  feces  is  prevented. 
This  habitual  closure  of  the  sphincter  depends  on  the  reflex  action 
of  the  spinal  cord.  It  is  entirely  an  involuntary  act,  and  will  con- 
tinue, in  the  healthy  condition,  during  profound  sleep,  as  complete 
and  efficient  as  in  the  waking  state. 

When  the  rectum,  however,  has  become  filled  by  the  accumula- 
tion of  feces  from  above,  the  nervous  action  changes.  Then  the 
impression  produced  on  the  mucous  membrane  of  the  distended 
rectum,  conveyed  to  the  spinal  cord,  causes  at  the  same  time  re- 
laxation of  the  sphincter  and  contraction  of  the  rectum  itself;  so 
that  a  discharge  of  the  feces  consequently  takes  place. 

Now  all  these  actions  are  to  some  extent  under  the  control  of 
sensation  and  volition.  The  distended  state  of  the  rectum  is  usually 
accompanied  by  a  distinct  sensation,  and  the  resistance  of  the 
sphincter  may  be  voluntarily  prolonged  for  a  certain  period,  just  as 
the  respiratory  movements,  which  are  usually  involuntary,  may  be 
intentionally  hastened  or  retarded,  or  even  temporarily  suspended. 
But  this  voluntary  power  over  the  sphincter  and  the  rectum  is 
limited.  After  a  time  the  involuntary  impulse,  growing  more  and 
more  urgent  with  the  increased  distension  of  the  rectum,  becomes 
irresistible;  and  the  discharge  finally  takes  place  by  the  simple 
reflex  action  of  the  spinal  cord. 

If  the  spinal  cord  be  injured  in  its  middle  or  upper  portions,  the 
sensibility  and  voluntary  action  of  the  sphincter  is  lost,  because  its 
connection  with  the  brain  has  been  destroyed.  The  evacuation 
then  takes  place  at  once,  by  the  ordinary  mechanism,  as  soon  as 
the  rectum  is  filled,  but  without  any  knowledge  on  the  part  of  the 
patient.  The  discharges  are  then  said  to  be  "  involuntary  and  un- 
conscious." 

If  the  irritability  of  the  cord,  on  the  other  hand,  be  exaggerated 
by  disease,  while  its  connection  with  the  brain  remains  entire,  the 


KEFLEX    ACTION    OF    THE    SrilSTAL    CORD.  355 

distension  of  the  rectum  is  announced  by  the  usual  sensation,  but 
the  reflex  impulse  to  evacuation  is  so  urgent  that  it  cannot  be 
controlled  bj  the  will,  and  the  patient  is  compelled  to  allow  it  to 
take  place  at  once.  The  discharges  are  then  said  to  be  simply 
'*  involuntary." 

Finally,  if  the  substance  of  the  spinal  cord  be  extensively  de- 
stroyed by  accident  or  disease,  the  sphincter  is  permanently  relaxed. 
The  feces  are  then  evacuated  almost  continuously,  without  any 
knowledge  or  control  on  the  part  of  the  patient,  as  fast  as  they 
descend  into  the  rectum  from  the  upper  portions  of  the  intestine. 

Injury  of  the  spinal  cord  produces  a  somewhat  different  effect 
on  the  urinary  bladder.  Its  muscular  fibres  are  directly  para- 
lyzed ;  and  the  organ,  being  partially  protected  by  elastic  fibres, 
both  at  its  own  orifice  and  along  the  urethra,  becomes  gradually 
distended  by  urine  from  the  kidneys.  The  urine  then  overcomes 
the  elasticity  of  the  protecting  fibres,  by  simple  force  of  accumula- 
tion, and  afterward  dribbles  away  as  fast  as  it  is  excreted  by  the 
kidneys.  Paralysis  of  the  bladder,  therefore,  first  causes  a  perma- 
nent distension  of  the  organ,  which  is  afterward  followed  by  a 
continuous,  passive,  and  incomplete  discharge  of  its  contents. 

Injury  of  the  spinal  cord  produces  also  an  important,  though 
probably  an  indirect  effect  on  nutrition,  secretion,  animal  heat,  &c., 
in  the  paralyzed  parts.  Diseases  of  the  cord  which  result  in  its 
softening  or  disintegration,  are  notoriously  accompanied  by  consti- 
pation, often  of  an  extremely  obstinate  character.  In  complete 
paraplegia,  also,  the  lower  extremities  become  emaciated.  The 
texture  and  consistency  of  the  muscles  are  altered,  and  the  animal 
temperature  is  considerably  reduced.  All  such  disturbances  of 
nutrition,  however,  which  follow  almost  invariably  upon  local  para- 
lysis are  no  doubt  immediately  owing  to  the  inactive  condition  of 
the  muscles;  a  condition  which  naturally  induces  debility  of  the 
circulation,  and  consequently  of  all  those  functions  which  are 
dependent  upon  it. 

It  is  less  easy  to  explain  the  connection  between  injury  of  the 
spinal  cord  and  inflammation  of  the  urinary  passages.  It  is,  how- 
ever, a  matter  of  common  observation  among  pathologists,  that 
injury  or  disease  of  the  cord,  particularly  in  the  dorsal  and  upper 
lumbar  regions,  is  soon  followed  by  catarrhal  inflammation  of  the 
urinary  passages.  This  gives  rise  to  an  abundant  production  of 
altered  mucus,  which  in  its  turn,  by  causing  an  alkaline  fermenta- 
tion in  the  urine  contained  in  the  bladder,  converts  it  into  an  irri- 


356  THE    SPINAL    CORD. 

tating   and   ammoniacal   liquid,   which   reacts   upon   the   nnucous 
membrane  and  aggravates  the  previous  inflammation. 

We  find,  therefore,  that  the  spinal  cord,  in  its  character  of  a 
nervous  centre,  exerts  a  general  protective  action  over  the  whole 
body.  It  presides  over  the  involuntary  movements  of  the  limbs 
and  trunk  ;  it  regulates  the  action  of  the  sphincters,  the  rectum, 
and  the  bladder;  while  at  the  same  time  it  exerts  an  indirect  influ- 
ence on  the  nutritive  changes  in  those  parts  which  it  supplies  with 
nerves. 


THE    BRAIN.  857 


CHAPTER    IV. 

THE    BRAIN. 

By  the  brain,  or  encephalon,  as  it  is  sometimes  called,  we  mean  all 
that  portion  of  the  nervous  system  which  is  situated  within  the 
cavity  of  the  cranium.  It  consists,  as  we  have  already  shown,  of 
a  series  of  different  ganglia,  connected  with  each  other  by  transverse 
and  longitudinal  commissures. 

Since  we  have  found  the  functions  of  sensation  and  motion,  or 
sensibility  and  excitability,  so  distinctly  separated  in  the  spinal 
cord,  we  should  expect  to  find  the  same  distinction  in  the  interior 
of  the  brain.  These  two  properties  have  indeed  been  found  to  be 
distinct  from  each  other,  so  far  as  they  exist  at  all,  in  the  encephalic 
mass ;  but  it  is  a  very  remarkable  fact  that  they  are  both  confined 
to  very  small  portions  of  the  brain,  in  comparison  with  its  entire 
bulk.  According  to  the  investigations  of  Longet,  neither  the 
olfactory  ganglia,  the  corpora  striata,  the  optic  thalami,  the  tuber- 
cula  quadrigemina,  nor  the  white  or  gray  substance  of  the  cerebrum 
or  the  cerebellum,  are  in  the  least  degree  excitable.  Mechanical 
irritation  of  these  parts  does  not  produce  the  slightest  convulsive 
movement  in  the  muscles  below.  The  application  of  caustic  liquids 
and  the  passage  of  galvanic  currents  are  equally  without  effect. 
The  only  portions  of  the  brain  in  which  irritation  is  followed  by 
convulsive  movements  are  the  anterior  surface  of  the  medulla  ob- 
longata, the  tuber  annulare,  and  the  lower  part  of  the  crura  cerebri; 
that  is,  the  lower  and  central  parts  of  the  brain,  containing  continu- 
ations of  the  anterior  columns  of  the  cord.  On  the  other  hand, 
neither  the  olfactory  ganglia,  the  corpora  striata,  the  tubercula 
quadrigemina  nor  the  white  or  gray  substance  of  the  cerebrum  or 
cerebellum,  give  rise,  on  being  irritated,  to  any  painful  sensation. 
The  only  sensitive  parts  are  the  posterior  surfiice  of  the  medulla 
oblongata,  the  restiform  bodies,  the  processus  e  cerebello  ad  testes, 
and  the  upper  part  of  the  crura  cerebri ;  that  is,  those  portions  of 


358  THE    BRAIN". 

the  base  of  the  brain  which  contain  prolongations  of  the  posterior 
columns  of  the  cord 

The  most  central  portions  of  the  nervous  system,  therefore,  and 
particularly  the  gray  matter,  are  destitute  of  both  excitability  and 
sensibility.  It  is  only  those  portions  which  serve  to  conduct  sen- 
sations and  nervous  impulses  that  can  be  excited  by  mechanical 
irritation;  not  the  ganglionic  centres  themselves,  which  receive  and 
originate  the  nervous  impressions. 

"We  shall  now  study  in  succession  the  different  ganglia  of  which 
the  brain  is  composed. 


OLFACTORY  GANGLIA. 

These  ganglia,  which  in  some  of  the  lower  animals  are  very 
large,  corresponding  in  size  with  the  extent  of  the  Schneiderian 
mucous  membrane  and  the  acuteness  of  the  sense  of  smell,  are  very 
small  in  the  human  subject.  They  are  situated  on  the  cribriform 
plate  of  the  ethmoid  bone,  on  each  side  of  the  crista  galli,  just  be- 
neath the  anterior  lobes  of  the  cerebrum.  They  send  their  nerves 
through  the  numerous  perforations  which  exist  in  the  ethmoid  bone 
at  this  part,  and  are  connected  with  the  base  of  the  brain  by  two 
longitudinal  commissures.  The  olfactory  ganglia  with  their  com- 
missures are  sometimes  spoken  of  as  the  "olfactory  nerves."  They 
are  not  nerves,  however,  but  ganglia,  since  they  are  mostly  com- 
posed of  gray  matter ;  and  the  term  "  olfactory  nerves"  can  be 
properly  applied  only  to  the  filaments  which  originate  from  them, 
and  which  are  afterward  spread  out  in  the  substance  of  the  Schnei- 
derian mucous  membrane. 

It  has  been  found  difficult  to  determine  the  function  of  these 
ganglia  by  direct  experiment  on  the  lower  animals.  They  may  be 
destroyed  by  means  of  a  strong  needle  introduced  through  the  bones 
of  the  cranium ;  but  the  signs  of  the  presence  or  absence  of  the 
sense  of  smell,  after  such  an  operation,  are  too  indefinite  to  allow  us 
to  draw  from  them  a  decided  conclusion.  The  anatomical  distribu- 
tion of  their  nerves,  however,  and  the  evident  correspondence  which 
exists,  in  different  species  of  animals,  between  their  degree  of  de- 
velopment and  that  of  the  external  olfactory  organs,  leaves  no  doubt 
as  to  their  true  function.  They  are  the  ganglia  of  the  special  sense 
of  smell,  and  are  not  connected,  in  any  appreciable  degree,  with 


OPTIC    THALAMI, — CORPORA    STRIATA.  —  HEMISPHERES.    859 

ordinary  sensibility,  nor  with  the  production  of  voluntary  move- 
ments. 

OFTIC  THALAMI. 

These  bodies  are  not,  as  their  name  would  imply,  the  ganglia  of 
vision.  Longet  has  found  that  the  power  of  sight  and  the  sensi- 
bility of  the  pupil  both  remain,  in  birds,  after  the  optic  thalami 
have  been  thoroughly  disorganized ;  and  that  artificial  irritation  of 
the  same  ganglia  has  no  effect  in  producing  either  contraction  or 
dilatation  of  the  pupil.  The  optic  thalami,  however,  according  to 
the  same  observer,  have  a  peculiar  crossed  action  upon  the  volun- 
tary movements.  If  both  hemispheres  and  both  optic  thalami  be 
removed  in  the  rabbit,  the  animal  is  still  capable  of  standing  and 
of  "using  his  limbs  in  progression.  But  if  the  right  optic  thalamus 
alone  be  removed,  the  animal  falls  at  once  upon  his  left  side;  and 
if  the  left  thalamus  be  destroyed,  a  similar  debility  is  manifest  on 
the  right  side  of  the  body.  In  these  instances  there  is  no  absolute 
paralysis  of  the  side  upon  which  the  animal  falls,  but  rather  a 
simple  want  of  balance  between  the  two  opposite  sides.  The  exact 
mechanism  of  this  peculiar  functional  disturbance  is  not  well 
understood;  and  but  little  light  has  yet  been  thrown,  either  by 
direct  experiment  or  by  the  facts  of  comparative  anatomy,  on  the 
real  function  of  the  optic  thalami. 


CORPORA  STRIATA. 

The  function  of  these  ganglia  is  equally  uncertain  with  that  of 
the  preceding.  They  are  traversed,  as  we  have  already  seen,  by 
fibres  coming  from  the  anterior  columns  of  the  cord;  and  they  are 
connected,  by  the  continuation  of  these  fibres,  with  the  gray  sub- 
stance of  the  hemispheres.  They  have,  therefore,  in  all  probability, 
like  the  optic  thalami,  some  connection  with  sensation  and  volition; 
but  the  precise  nature  of  this  connection  is  at  present  altogether 
unknown. 

HEMISPHERES. 

The  hemispheres,  or  the  cerebral  ganglia,  constitute  in  the 
human  subject  about  nine  tenths  of  the  whole  mass  of  the  brain. 


360  THE    BRAIN. 

Throughout  their  whole  extent  they  are  entirely  destitute,  as  we 
have  already  mentioned,  of  both  sensibility  and  excitability.  Both 
the  white  and  gray  substance  may  be  wounded,  burned,  lacerated, 
crushed,  or  galvanized  in  the  living  animal,  without  exciting  any 
convulsive  movement  or  any  apparent  sensation.  In  the  human 
subject  a  similar  insensibility  has  been  observed  when  the  sub- 
stance of  the  hemispheres  has  been  exposed  by  accidental  violence, 
or  in  the  operation  of  trephining. 

Yery  severe  mechanical  injuries  may  also  be  inflicted  upon  the 
hemispheres,  even  in  the  human  subject,  without  producing  any 
directly  fatal  result.  One  of  the  most  remarkable  instances  of  this 
fact  is  a  case  reported  by  Dr.  William  Detmold,  of  New  York,'  in 
which  an  abscess  in  the  anterior  lobe  of  the  brain  was  opened  by  an 
incision  passing  through  the  cerebral  substance,  not  only  without 
any  immediate  bad  effect,  but  with  great  temporary  relief  to  the 
patient.  This  was  the  case  of  a  laborer  who  was  struck  on  the  left 
side  of  the  forehead  by  a  piece  of  falling  timber,  which  produced  a 
compound  fracture  of  the  skull  at  this  part.  One  or  two  pieces 
of  bone  afterward  became  separated  and  were  removed,  and  the 
wound  subsequently  healed.  Nine  weeks  after  the  accident,  how- 
ever, headache  and  drowsiness  came  on ;  and  the  latter  symptom, 
becoming  rapidly  aggravated,  soon  terminated  in  complete  stupor. 
At  this  time,  the  existence  of  an  abscess  being  suspected,  the 
cicatrix,  together  with  the  adherent  portion  of  the  dura  mater,  was 
dissected  away,  several  pieces  of  fractured  bone  removed,  and  the 
surface  of  the  brain  exposed.  A  knife  was  then  passed  into  the 
cerebral  substance,  making  a  wound  one  inch  in  length  and  half 
an  inch  in  depth,  when  the  abscess  was  reached  and  about  liij  of 
pus  discharged.  I^he  patient  immediately  aroused  from  his  coma- 
tose condition,  so  that  he  was  able  to  speak;  and  in  a  few  days 
recovered,  to  a  very  considerable  extent,  his  cheerfulness,  intelli- 
gence, and  appetite.  Subsequently,  however,  the  collection  of  pus 
returned,  accompanied  by  a  renewal  of  the  previous  symptoms; 
and  the  patient  finally  died  at  the  end  of  seven  weeks  from  the 
time  of  opening  the  abscess. 

Another  and  still  more  striking  instance  of  recovery  from  severe 
injury  of  the  brain  is  reported  by  Prof.  H.  J.  Bigelow  in  the 
American  Journal  of  Medical  Sciences  for  July,  1850.  In  this  case,  a 
pointed  iron  bar,  three  feet  and  a  half  in  length,  and  one  inch  and  a 

'  Am.  Joiirn.  of  Med.  Sci.,  January,  1850. 


HEMISPHERES.  361 

quarter  in  diameter,  was  driven  through  the  patient's  head  by  the 
premature  blasting  of  a  rock.  The  bar  entered  the  left  side  of  the 
face,  just  in  front  of  the  angle  of  the  jaw,  and  passed  obliquely 
upward,  inside  the  zygomatic  arch  and  through  the  anterior  part 
of  the  cranial  cavity,  emerging  from  the  top  of  the  frontal  bone  on 
the  median  line,  just  in  front  of  the  point  of  union  of  the  coronal 
and  sagittal  sutures.  The  patient  was  at  first  stunned,  but  soon 
recovered  himself  so  far  as  to  be  able  to  converse  intelligently,  rode 
home  in  a  common  cart,  and  with  a  little  assistance  walked  up  stairs 
to  his  room.  He  became  delirious  within  two  days  after  the  acci- 
dent, and  subsequently  remained  partly  delirious  and  partly  coma- 
tose for  about  three  weeks.  He  then  began  to  improve,  and  at  the 
end  of  rather  more  than  two  months  from  the  date  of  the  injury, 
was  able  to  walk  about.  At  the  end  of  sixteen  months  he  was  in 
perfect  health,  with  the  wounds  healed,  and  with  the  mental  and 
bodily  functions  entirely  unimpaired,  except  that  sight  was  perma- 
nently lost  in  the  eye  of  the  injured  side. 

The  hemispheres,  furthermore,  are  not  the  seat  of  sensation  or  of 
volition,  nor  are  they  immediately  essential  to  the  continuance  of 
life.  In  quadrupeds,  the  complete  removal  of  the  hemispheres  is 
attended  with  so  much  hemorrhage  that  the  operation  is  generally 
fatal  from  this  cause  within  a  few  minutes.  In  birds,  however,  it 
may  be  performed  without  any  immediate  danger  to  life.  Longet 
has  removed  the  hemispheres  in  pigeons  and  fowls,  and  has  kept 
these  animals  afterward  for  several  days,  with  most  of  the  organic 
functions  unimpaired.  We  have  frequently  performed  the  same 
experiment  upon  pigeons,  with  a  similarly  favorable  result. 

The  effect  of  this  mutilation  is  simply  to  plunge  the  animal  into 
a  state  of  profound  stupor,  in  which  he  is  almost  entirely  inatten- 
tive to  surrounding  objects.  The  bird  remains  sitting  motionless 
upon  his  perch,  or  standing  upon  the  ground,  with  the  eyes  closed, 
and  the  head  sunk  between  the  shoulders.  (Fig.  138.)  The  plu- 
mage is  smooth  and  glossy,  but  is  uniformly  expanded,  by  a  kind 
of  erection  of  the  feathers,  so  that  the  body  appears  somewhat 
puffed  out,  and  larger  than  natural.  Occasionally  the  bird  opens 
his  eyes  with  a  vacant  stare,  stretches  his  neck,  perhaps  shakes  his 
bill  once  or  twice,  or  smooths  down  the  feathers' upon  his  shoulders, 
and  then  relapses  into  his  former  apathetic  condition.  This  state 
of  immobility,  however,  is  not  accompanied  by  the  loss  of  sight,  of 
hearing,  or  of  ordinary  sensibility.  All  these  functions  remain,  as 
well  as  that  of  voluntary  motion.     If  a  pistol  be  discharged  behind 


362 


THE    BRAIN. 


the  back  of  the  animal,  he  at  once  opens  his  eyes,  moves  his  head 
half  round,  and  gives  evident  signs  of  having  heard  the  report;  but 
he  immediately  becomes  quiet,  again,  and  pays  no  farther  attention 
to  it.     Sight  is  also  retained,  since  the  bird  will  sometimes  fix  its 

Fig.  138. 


PiGEOX,     AFTER     REMOVAL    OF    THE     HEMISPHERES. 


eye  on  a  particular  object,  and  watch  it  for  several  seconds  together. 
Longet  has  even  found  that  by  moving  a  lighted  candle  before  the 
animal's  eyes  in  a  dark  place,  the  head  of  the  bird  will  often  follow 
the  movements  of  the  candle  from  side  to  side  or  in  a  circle,  showing 
that  the  impression  of  light  is  actually  perceived  by  the  sensoriura. 
Ordinary  sensation  also  remains,  after  removal  of  the  hemispheres, 
together  with  voluntary  motion.  If  the  foot  be  pinched  with  a 
pair  of  forceps,  the  bird  becomes  partially  aroused,  moves  uneasily 
once  or  twice  from  side  to  side,  and  is  evidently  annoyed  at  the 
irritation. 

The  animal  is  still  capable,  therefore,  after  removal  of  the  hemi- 
spheres, of  receiving  sensations  from  external  objects.  But  these 
sensations  appear  to  make  upon  him  no  lasting  impression.  He  is 
incapable  of  connecting  with  his  perceptions  any  distinct  succession 
of  ideas.  He  hears,  for  example,  the  report  of  a  pistol,  but  he  is  not 
alarmed  by  it ;  for  the  sound,  though  distinctly  enough  perceived, 
does  not  suggest  any  idea  of  danger  or  injury.  There  is  accord- 
ingly no  power  of  forming  mental  associations,  nor  of  perceiving 
the  relation  between  external  objects.  The  memory,  more  particu- 
larly, is  altogether  destroyed,  and  the  recollection  of  sensations  is 
not  retained  from  one  moment  to  another.  The  limbs  and  muscles 
are  still  under  the  control  of  the  will ;  but  the  will  itself  is  inactive. 


HEMISPHERES.  363 

because  apparently  it  lacks  its  usual  mental  stimulus  and  direction. 
The  powers  whicli  have  been  lost,  therefore,  by  destruction  of  the 
cerebral  hemispheres,  are  altogether  of  a  mental  or  intellectual 
character;  that  is,  the  power  of  comparing  with  each  other  different 
ideas,  and  of  perceiving  the  proper  relation  between  them. 

The  same  result  is  well  known  to  follow,  in  the  human  subject, 
from  injury  or  disease  of  these  parts.  A  disturbance  of  the  mental 
powers  has  long  been  recognized  as  the  ordinary  consequence  of 
lesions  of  the  brain.  In  cases  of  impending  apoplexy,  for  example, 
or  of  softening  of  the  cerebral  substance,  among  the  earliest  and 
most  constant  phenomena  is  a  loss  or  impairment  of  the  memory. 
The  patient  forgets  the  names  of  particular  objects  or  of  particular 
persons  ;  or  he  is  unable  to  calculate  numbers  with  his  usual  facility. 
His  mental  derangement  is  often  shown  in  the  undue  estimate  which 
he  forms  of  passing  events.  He  is  no  longer  able  to  appreciate  the 
true  relation  between  different  objects  and  different  phenomena. 
Thus,  he  will  show  an  exaggerated  degree  of  solicitude  about  a 
trivial  occurrence,  and  will  pay  no  attention  to  other  matters  of 
real  importance.  As  the  difficulty  increases,  he  becomes  careless 
of  the  directions  and  advice  of  his  attendants,  and  must  be  watched 
and  managed  like  a  child  or  an  imbecile.  After  a  certain  period, 
he  no  longer  appreciates  the  lapse  of  time,  and  even  loses  the  dis- 
tinction between  day  and  night.  Finally,  when  the  injury  to  the 
hemispheres  is  complete,  the  senses  may  still  remain  active  and 
impressible,  while  the  patient  is  completely  deprived  of  intelligence, 
memory,  and  judgment. 

If  we  examine  the  comparative  development  of  the  hemispheres 
in  different  species  of  animals,  and  in  different  races  of  men,  we 
shall  find  that  the  size  of  these  ganglia  corresponds  very  closely 
with  the  degree  of  intelligence  possessed  by  the  individual.  We 
have  already  traced,  in  a  preceding  chapter,  the  gradual  increase 
in  size  of  the  hemispheres  in  fish,  reptiles,  birds  and  quadrupeds: 
four  classes  of  animals  which  may  be  arranged,  with  regard  to  the 
amount  of  intelligence  possessed  by  each,  in  precisely  the  same 
order  of  succession.  Among  quadrupeds,  the  elephant  has  much 
the  largest  and  most  perfectly  formed  cerebrum,  in  proportion  to 
the  size  of  the  entire  body;  and  of  all  quadrupeds  he  is  proverbially 
the  most  intelligent  and  the  most  teachable.  It  is  important  to 
observe,  in  this  connection,  that  the  kind  of  intelligence  which 
characterizes  the  elephant  and  some  other  of  the  lower  animals, 
and  which  most  nearly  resembles  that  of  man,  is  a  teachable  intelli- 


364  THE    BRAIN. 

gence;  a  very  different  thing  from  the  intelligence  which  depends 
upon  instinct,  such  as  that  of  insects,  for  example,  or  birds  of  pas- 
sage. Instinct  is  unvarying,  and  always  does  the  same  thing  in  the 
same  manner,  with  endless  repetition  ;  but  intelligence  is  a  power 
which  adapts  itself  to  new  circumstances,  and  enables  its  possessor, 
by  comprehending  and  retaining  new  ideas,  to  profit  by  experience. 
It  is  this  quality  which  distinguishes  the  higher  classes  of  animals 
from  the  lower;  and  which,  in  a  very  much  greater  degree,  con- 
stitutes the  intellectual  superiority  of  man  himself.  The  size 
of  the  cerebrum  in  man  is  accordingly  very  much  greater,  in  pro- 
portion to  that  of  the  entire  body,  than  in  any  of  the  lower  animals; 
while  other  parts  of  the  brain,  on  the  contrary,  such  as  the  olfactory 
ganglia  or  the  optic  tubercles,  are  frequently  smaller  in  him  than 
in  them.  For  while  man  is  superior  in  general  intelligence  to  all 
the  lower  animals,  he  is  inferior  to  many  of  them  in  the  acuteness 
of  tlie  special  senses. 

As  a  general  rule,  also,  the  size  of  the  cerebrum  in  different 
races  and  in  different  individuals  corresponds  with  the  grade  of 
their  intelligence.  The  size  of  the  cranium,  as  compared  with  that 
of  the  face,  is  smallest  in  the  savage  negro  and  Indian  tribes;  larger 
in  the  civilized  or  semi-civilized  Chinese,  Malay,  Arab,  and  Japan- 
ese; while  it  is  largest  of  all  in  the  enlightened  European  races. 
This  difference  in  the  development  of  the  brain  is  not  probably  an 
effect  of  long-continued  civilization  or  otherwise;  but  it  is,  on  the 
contrary,  the  superiority  in  cerebral  development  which  makes 
some  races  readily  susceptible  of  civilization,  while  others  are 
either  altogether  incapable  of  it,  or  can  only  advance  in  it  to  a 
certain  limit.  Although  all  races  therefore  may,  perhaps,  be  said 
to  start  from  the  same  level  of  absolute  ignorance,  yet  after  the 
lapse  of  a  certain  time  one  race  will  have  advanced  farther  in 
civilization  than  another,  owing  to  a  superior  capacity  for  improve- 
ment, dependent  on  original  organization. 

The  same  thing  is  true  with  regard  to  different  individuals.  At 
birth,  all  men  are  equally  ignorant ;  and  yet  at  the  end  of  a  certain 
period  one  will  have  acquired  a  very  much  greater  intellectual 
power  than  another,  even  under  similar  conditions  of  training, 
education,  &c.  He  has  been  able  to  accumulate  more  information 
from  the  same  sources,  and  to  use  the  same  experience  to  better 
advantage  than  his  associates ;  and  the  result  of  this  is  a  certain 
intellectual  superiority,  which  becomes  still  greater  by  its  own 
exercise.     This  superiority,  it  will  be  observed,  lies  not  so  much 


HEMISPHERES.  365 

in  tlie  power  of  perceiving  external  objects  and  events,  and  of 
recognizing  the  connection  between  tliem,  as  in  that  of  drawing 
conclusions  from  one  fact  to  another,  and  of  adapting  to  new  com- 
binations the  knowledge  which  has  already  been  acquired. 

It  is  this  particular  kind  of  intellectual  difference,  existing  in  a 
marked  degree  between  animals,  races,  and  individuals,  which  cor- 
responds with  the  difference  in  development  of  the  cerebral  hemi- 
spheres. We  have,  therefore,  evidence  from  three  different  sources 
that  the  cerebral  hemispheres  are  the  seat  of  the  reasoning  powers,. 
or  of  the  intellectual  faculties  proper.  First,  when  these  ganglia 
are  removed,  in  the  lower  animals,  the  intellectual  faculties  are  the 
only  ones  which  are  lost.  Secondly,  injury  to  these  ganglia,  in  the 
human  subject,  is  followed  by  a  corresponding  impairment  of  the 
same  faculties.  Thirdly,  in  different  species  of  animals,  as  well  as 
in  different  races  of  men  and  in  different  individuals,  the  develop- 
ment of  these  faculties  is  in  proportion  to  that  of  the  cerebral 
hemispberes. 

When  we  say,  however,  that  the  hemispheres  are  the  seat  of  the 
intellectual  faculties,  of  memory,  reason,  judgment,  and  the  like, 
we  do  not  mean  that  these  faculties  are,  strictly  speaking,  located 
in  the  substance  of  the  hemispheres,  or  that  they  belong  directly  to 
the  matter  of  which  the  hemispheres  are  composed.  The  hemi- 
spherical ganglia  are  simply  the  instruments  through  which  the 
intellectual  powers  manifest  themselves,  and  which  are  accordingly 
necessary  to  their  operation.  If  these  instruments  be  imperfect  in 
structure,  or  be  damaged  in  any  manner  by  violence  or  disease,  the 
manifestations  of  intelligence  are  affected  in  a  corresponding  degree. 
So  far,  therefore,  as  the  mental  faculties  are  the  subject  of  physio- 
logical research  and  experiment,  they  are  necessarily  connected 
with  the  hemispherical  ganglia;  and  the  result  of  investigation 
shows  this  connection  to  be  extremely  intimate  and  important  in 
its  character. 

There  are,  however,  various  circumstances  which  modify,  in 
particular  cases,  the  general  rule  given  above,  viz.,  that  the  larger 
the  cerebrum  the  greater  the  intellectual  superiority.  The  func- 
tional activity  of  the  brain  is  modified,  no  doubt,  by  its  texture  as 
well  as  by  its  size ;  and  an  increased  excitability  may  compensate, 
partially  or  wholly,  for  a  deficiency  in  bulk.  This  fact  is  some- 
times illustrated  in  the  case  of  idiots.  There  are  instances  where 
idiotic  children  with  small  brains  are  less  imbecile  and  helpless 
than  others  with  a  larger  development,  owing  to  a  certain  vivacity 


366 


THE    BRAIl^. 


and  impressibility  of  organization  which  take  the  place,  to  a  cer- 
tain extent,  of  the  purely  intellectual  faculties. 

This  was  the  case,  in  a  marked  degree,  with  a  pair  of  dwarfed 
and  idiotic  Central  American  children,  who  were  exhibited  a  few 
years  ago  in  various  parts  of  the  United  States,  under  the  name  of 
the  "Aztec  children."  They  were  a  bo}'  and  a  girl,  aged  respectively 
about  seven  and  five  years.  The  boy  was  2  feet  9|  inches  high,  and 
weighed  a  little  over  20  pounds.  The  girl  was  2  feet  5|  inches 
high,  and  weighed  17  pounds.  Their  bodies  were  tolerably  well 
proportioned,  but  the  cranial  cavities,  as  shown  by  the  accompan}^- 
ing  portraits,  were  extremely  small. 

Fig.  139. 


Aztec   Children.— Taken  from  life. 

The  antero-posterior  diameter  of  the  boy's  head  was  only  4| 
inches,  the  transverse  diameter  less  than  4  inches.  The  antero- 
posterior diameter  of  the  girl's  head  was  4J  inches,  the  transverse 
diameter  only  3|  inches.  The  habits  of  these  children,  so  far  as 
regards  feeding  and  taking  care  of  themselves,  were  those  of  chil- 
dren two  or  three  years  of  age.  They  were  incapable  of  learning 
to  talk,  and  could  only  repeat  a  few  isolated  words.  Notwithstand- 
ing, however,  the  extremely  limited  range  of  their  intellectual 
powers,  these  children  were  remarkably  vivacious  and  excitable. 
While  awake  they  were  in  almost  constant  motion,  and  any  new 
object  or  toy  presented  to  them  immediately  attracted  their  atten- 
tion, and  evidently  awakened  a  lively  curiosity.  They  were  ac- 
cordingly easily  influenced  by  proper  management,  and  understood 
readily  the  meaning  of  those  who  addressed  them,  so  far  as  this 
meaning  could  be  conveyed  by  gesticulation  and  the  tones  of  the 
voice.  Their  expression  and  general  appearance,  though  decidedly 
idiotic,  were  not  at  all  disagreeable  or  repulsive ;  and  they  were 


HEMISPHEEES.  367 

much  less  troublesome  to  the  persons  who  had  them  in  charge  than 
is  often  the  case  with  idiots  possessing  a  larger  cerebral  development. 

It  may  also  be  observed  that  the  purely  intellectual  or  reasoning 
powers  are  not  the  only  element  in  the  mental  superiority  of 
certain  races  or  of  particular  individuals  over  their  associates. 
There  is  also  a  certain  rapidity  of  perception  and  strength  of  will 
which  may  sometimes  overbalance  greater  intellectual  acquirements 
and  more  cultivated  reasoning  powers.  These,  however,  are  differ- 
ent faculties  from  the  latter ;  and  occupy,  as  we  shall  hereafter  see, 
different  parts  of  the  encephalon. 

A  very  remarkable  physiological  doctrine,  dependent  partly  on 
the  foregoing  facts,  was  brought  forward  some  years  ago  by  Gall 
and  Spurzheim,  under  the  name  of  Phrenology.  These  observers 
recognized  the  fact  that  the  intellectual  powers  are  undoubtedly 
seated  in  the  brain,  and  that  the  development  of  the  brain  is,  as  a 
general  rule,  in  correspondence  with  the  activity  of  these  powers. 
They  noticed  also  that  in  other  parts  of  the  nervous  system,  different 
functions  occupy  different  situations ;  and  regarding  the  mind  as 
made  up  of  many  distinct  mental  faculties,  they  conceived  the  idea 
that  these  different  faculties  might  be  seated  in  different  parts  of 
the  cerebral  mass.  If  so,  each  separate  portion  of  the  brain  would 
undoubtedly  be  more  or  less  developed  in  proportion  to  the  activity 
of  the  mental  trait  or  faculty  residing  in  it.  The  shape  of  the  head 
would  then  vary  in  different  individuals,  in  accordance  with  their 
mental  peculiarities;  and  the  character  and  endowments  of  the 
individual  might  therefore  be  estimated  from  an  examination  of 
the  elevations  and  depressions  on  the  surface  of  the  cranium. 

Accordingly,  the  authors  of  this  doctrine  endeavored,  by  examin- 
ing the  heads  of  various  individuals  whose  character  was  already 
known,  to  ascertain  the  location  of  the  different  mental  faculties. 
In  this  manner  they  finally  succeeded,  as  they  supposed,  in  accom- 
plishing their  object;  after  which  they  prepared  a  chart,  in  which 
the  surface  of  the  cranium  was  mapped  out  into  some  thirty  or  forty 
different  regions,  corresponding  with  as  many  different  mental  traits 
or  faculties.  With  the  assistance  of  this  chart  it  was  thought  that 
phrenology  might  be  practised  as  an  art ;  and  that,  by  one  skilled 
in  its  application,  the  character  of  a  stranger  might  be  discovered 
by  simply  examining  the  external  conformation  of  his  head. 

We  shall  not  expend  much  time  in  discussing  the  claims  of  phre- 
nology to  rank  as  a  science  or  an  art,  since  we  believe  that  it  has 
of  late  years  been  almost  wholly  discarded  by  scientific  men,  owing 


368  THE    BRAIN. 

to  the  very  evident  deficiencies  of  the  basis  upon  which  it  was 
founded.  Passing  over,  therefore,  many  minor  details,  we  will 
merely  point  out,  as  matters  of  physiological  interest,  the  principal 
defects  which  must  always  prevent  the  establishment  of  phrenology 
as  a  science,  and  its  application  as  an  art. 

First,  though  we  have  no  reason  for  denying  that  different  parts 
of  the  brain  may  be  occupied  by  different  intellectual  faculties, 
there  is  no  direct  evidence  which  would  show  this  to  be  the  case. 
Phrenologists  include,  in  those  parts  of  the  brain  which  they  em- 
ploy for  examination,  both  the  cerebrum  and  cerebellum ;  and  they 
justly  regard  the  external  parts  of  these  bodies,  viz.,  the  layer  of 
gray  matter  which  occupies  their  surface,  as  the  ganglionic  portion 
in  which  must  reside  more  especially  the  nervous  functions  which 
they  possess.  But  this  layer  of  gray  matter,  in  each  principal  por- 
tion of  the  brain,  is  continuous  throughout.  There  is  no  anatomical 
division  or  limit  between  its  different  parts,  as  there  are  between 
the  different  ganglia  in  other  portions  of  the  nervous  system  ;  and 
consequently  such  divisions  of  the  cerebrum  and  cerebellum  must 
be  altogether  arbitrary  in  character,  and  not  dependent  on  any 
anatomical  basis. 

Secondly,  the  only  means  of  ascertaining  the  location  of  the 
different  mental  traits,  supposing  them  to  occupy  different  parts  of 
the  brain,  would  be  that  adopted  by  Gall  and  Spurzheim,  viz.,  to 
make  an  accurate  comparison,  in  a  sufficient  number  of  cases,  of  the 
form  of  the  head  in  individuals  of  known  character.  But  the  prac- 
tical difficulty  of  accomplishing  this  is  very  great.  It  requires  a 
long  acquaintance  and  close  observation  to  learn  accurately  the 
character  of  a  single  person;  and  it  is  in  this  kind  of  observation, 
more  than  in  any  other,  that  we  are  proverbially  liable  to  mis- 
takes. It  is  extremely  improbable,  therefore,  that  either  Gall  or 
Spurzheim  could,  in  a  single  lifetime,  have  accomplished  this  com- 
parison in  so  many  instances  as  to  furnish  a  reliable  basis  for  the 
construction  of  a  phrenological  chart. 

A  still  more  serious  practical  difficulty,  however,  is  the  following. 
The  different  intellectual  faculties  being  supposed  to  reside  in  the 
layer  of  gray  substance  constituting  the  surfaces  of  the  cerebrum 
and  cerebellum,  they  must  of  course  be  distributed  throughout  this 
layer,  wherever  it  exists.  Gall  and  Spurzheim  located  all  the  mental 
faculties  in  those  parts  of  the  brain  which  are  accessible  to  external 
exploration.  An  examination  of  different  sections  of  the  brain 
will  show,  however,  that  the  greater  portion  of  the  gray  substance 
is  so  placed,  that  its  quantity  cannot  be  estimated  by  an  external 


HEMISPHEEES. 


869 


Fig.  140. 


examination  througli  the  skull.  The  only  portions  which  are  ex- 
posed to  such  an  examination  are  the  upper  and  lateral  portions  of 
the  convexities  of  the  hemispheres,  together  with  the  posterior  edge 
and  part  of  the  under  surface  of  the  cerebellum.  (Fig.  140.)  A 
verj  extensive  portion  of  the  cerebral 
surface,  however,  remains  concealed  in 
such  a  manner  that  it  cannot  possibly  be 
subjected  to  examination,  viz.,  the  entire 
base  of  the  brain,  with  the  under  surface 
of  the  anterior  and  middle  lobes  (1,2  ); 
the  upper  surface  of  the  cerebellum  (3) 
and  the  inferior  surface  of  the  posterior 
lobe  of  the  cerebrum  which  covers  it  (4); 
that  portion  of  the  cerebellum  situated 
above  the  medulla  oblongata  (5);  and  the 
two  opposite  convoluted  surfaces  in  the 
fissure  of  Sylvius  (e,  7),  where  the  ante- 
rior and  middle  lobes  of  the  cerebrum 
lie  in  contact  with  each  other.   The  whole 

extent,  also,  of  the  cerebral  surfaces  which  are  opposed  to  each 
other  in  the  great  longitudinal  fissure  (Fig.  141),  throughout  its 
entire  length,  are  equally  protected  by  their 
position,  and  concealed  from  external  exa- 
mination. The  whole  of  the  convoluted 
surface  of  the  brain  must,  however,  be  re- 
garded as  of  equal  importance  in  the  distri- 
bution of  the  mental  qualities ;  and  yet  it  is 
evident  that  not  more  than  one-third  or  one- 
quarter  of  this  surface  is  so  placed  that  it 
can  be  examined  by  external  manipulation. 
It  must  furthermore  be  recollected  that  the 
gray  matter  of  the  cerebrum  and  cerebellum 
is  everywhere  convoluted,  and  that  the 
convolutions  penetrate  to  various  depths 
in  the  substance  of  the  brain.  Even  if  we  were  able  to  feel, 
therefore,  the  external  surface  of  the  brain  itself,  it  would  not  be 
the  entire  convolutions,  but  only  their  superficial  edges,  that  we 
should  really  be  able  to  examine.  And  yet  the  amount  of  gray 
matter  contained  in  a  given  space  depends  quite  as  much  upon  the 
depth  to  which  the  convolutions  penetrate,  as  upon  the  prominence 
of  their  edges. 
24 


Diagram  of  the  B k A i n  in  situ, 
showing  those  portious  which  are  ex- 
posed to  examination. 


Fig.  141. 


Transverse  section  of  B  r  a  t  x , 
showing  depth  of  great  longi- 
tudinal fissure,  at  a. 


370  THE    BRAIN. 

While  phrenology,  therefore,  is  partially  founded  upon  acknow- 
ledged physiological  facts,  there  are  yet  essential  deficiencies  in  its 
scientific  basis,  as  well  as  insurmountable  difficulties  in  the  way  of 
its  practical  application. 


CEREBELLUM. 

The  cerebellum  is  the  second  ganglion  of  the  encephalon,  in 
respect  of  size.  If  it  be  examined,  moreover,  in  regard  to  the  form 
and  disposition  of  its  convolutions,  it  will  be  seen  that  these  are 
much  more  complicated  and  more  numerous  than  in  the  cerebrum, 
and  penetrate  much  deeper  into  its  substance.  Though  the  cerebel- 
lum therefore  is  smaller,  as  a  whole,  than  the  cerebrum,  it  contains, 
in  proportion  to  its  size,  a  much  larger  quantity  of  gray  matter. 

In  examining  the  comparative  development  of  the  brain,  also,  in 
different  classes  and  species  of  animals,  we  find  that  the  cerebellum 
nearly  always  keeps  pace,  in  this  respect,  with  the  cerebrum.  These 
facts  would  lead  us  to  regard  it  as  a  ganglion  hardly  secondary  in 
importance  to  the  cerebrum  itself. 

Physiologists,  however,  have  thus  far  failed  to  demonstrate  the 
nature  of  its  function  with  the  same  degree  of  precision  as  that  of 
many  other  parts  of  the  brain.  The  opinion  of  Gall,  which  located 
in  the  cerebellum  the  sexual  impulse  and  instincts,  is  at  the  present 
day  generally  abandoned;  for  the  reason  that  it  has  not  been  found 
to  be  sufficiently  supported  by  anatomical  and  experimental  facts, 
many  of  which  are  indeed  directly  opposed  to  it.  The  opinion 
which  has  of  late  years  been  received  with  the  most  favor  is  that 
first  advocated  by  Flourens,  which  attributes  to  the  cerebellum  the 
power  of  associating  or  "co-ordinating"  the  different  voluntary 
movements. 

It  is  evident,  indeed,  that  such  a  power  does  actually  reside  in 
some  part  of  the  nervous  system.  No  movements  are  effected  by 
the  independent  contraction  of  single  muscles;  but  always  by 
several  muscles  acting  in  harmony  with  each  other.  The  number 
and  complication  of  these  associated  movements  vary  in  different 
classes  of  animals.  In  fish,  for  example,  progression  is  accom- 
plished in  the  simplest  possible  manner,  viz.,  by  the  lateral  flexion 
and  extension  of  the  vertebral  column.  In  serpents  it  is  much  the 
same.  In  frogs,  lizards,  and  turtles,  on  the  other  hand,  the  four 
jointed  extremities  come  into  play,  and  the  movements  are  some- 


CEKEBELLUM.  371 

what  complicated.  They  are  still  more  so  in  birds  and  quadrupeds; 
and  finally,  in  the  human  subject  they  become  both  varied  and 
complicated  in  the  highest  degree.  Even  in  maintaining  the  ordi- 
nary postures  of  standing  and  sitting,  there  are  many  different  mus- 
cles acting  together,  in  each  of  which  the  degree  of  contraction,  in 
order  to  preserve  the  balance  of  the  body,  must  be  accurately  pro- 
portioned to  that  of  the  others.  In  the  motions  of  walking  and 
running,  or  in  the  still  more  delicate  movements  of  the  hands  and 
fingers,  this  harmony  of  muscular  action  becomes  still  more  evident, 
and  is  seen  also  to  be  absolutely  indispensable  to  the  efficiency  of 
the  muscular  apparatus. 

The  opinion  which  locates  the  above  harmonizing  or  associating 
power  in  the  cerebellum  was  first  suggested  by  the  effects  observed 
after  experimentally  injuring  or  destroying  this  part  of  the  brain. 
If  the  cerebellum  be  exposed  in  a  living  pigeon,  and  a  portion  of 
its  substance  removed,  the  animal  exhibits  at  once  a  peculiar  un- 
certainty in  his  gait,  and  in  the  movement  of  his  wings.  If  the 
injury  be  more  extensive,  he 'loses  altogether  the  power  of  flight, 
and  can  walk,  or  even  stand,  only  with  great  difficulty.  This  is  not 
owing  to  any  actual  paralysis,  for  the  movements  of  the  limbs  are 
exceedingly  rapid  and  energetic;  but  is  due  to  a  peculiar  want  of 
control  over  the  muscular  contractions,  precisely  similar  to  that 
which  is  seen  in  a  man  in  a  state  of  intoxication.  The  movements 
of  the  legs  and  wings,  though  forcible  and  rapid,  are  confused  and 
blundering;  so  that  the  animal  cannot  direct  his  steps  to  any  par- 
ticular spot,  nor  support  himself  in  the  air  by  flight.  He  reels  and 
tumbles,  but  can  neither  walk  nor  fly. 

The  senses  and  intelligence  at  the  same  time  are  unimpaired.  It 
is  extremely  curious,  as  first  remarked  by  Longet,  to  compare  the 
different  phenomena  produced  by  removal  of  the  cerebrum  and  by 
that  of  the  cerebellum.  If  we  do  these  operations  upon  two  dif- 
ferent pigeons,  and  place  the  animals  side  by  side,  it  will  be  seen 
that  the  first  pigeon,  from  whom  the  cerebrum  only  has  been  re- 
moved, remains  standing  firmly  upon  his  feet,  in  a  condition  of 
complete  repose ;  and  that  when  aroused  and  compelled  to  stir,  he 
moves  sluggishly  and  unwillingly,  but  acts  otherwise  in  a  perfectly 
natural  manner.  The  second  pigeon,  on  the  other  hand,  from 
whom  the  cerebellum  only  has  been  taken  away,  is  in  a  constant 
state  of  agitation.  He  is  easily  terrified,  and  endeavors,  frequently 
with  violent  struggles,  to  escape  the  notice  of  those  who  are 
watching  him ;  but  his  movements  are  sprawling  and  unnatural. 


372  THE    BRAIN". 

and  are  evidently  no  longer  under  the  effectual  control  of  the  will, 
(B'ig.  142.)  If  the  entire  cerebellum  be  destroyed,  the  animal  is 
no  longer  capable  of  assuming  or  retaining  any  natural  posture. 
His  legs  and  wings  are  almost  constantly  agitated  with  ineffectual 

Fig.  142. 


PrOEON,    AFTER    REMOVAL    OF    THE    CeREBELI,  CM. 

struggles,  which  are  evidently  voluntary  in  character,  but  are  at 
the  same  time  altogether  irregular  and  confused.  Death  generally 
takes  place  after  this  operation  within  twenty-four  hours. 

The  results  of  the  above  experiment  are  extremely  constant  and 
invariable,  and  by  themselves  would  lead  us  to  adopt,  with  a  good 
degree  of  confidence,  the  opinion  of  Flourens.  This  opinion  evi- 
dently has  more  direct  evidence  in  its  favor  than  any  other  theory 
which  has  yet  been  broached  with  regard  to  the  function  of  the 
cerebellum.  Many  facts  derived  from  comparative  anatomy  tend, 
also,  to  confi.rm  the  same  opinion.  If  we  compare  different  classes 
of  animals  with  each  other,  as  fish  with  reptiles,  or  birds  with  quad- 
rupeds, in  which  the  development  and  activity  of  the  entire  nervous 
system  vary  extremely,  the  results  of  the  comparison  will  be  often 
contradictory;  but  if  we  compare  different  species  belonging  to 
the  same  class  and  order,  in  which  the  general  structure  and  plan 
of  organization  are  nearly  the  same,  we  often  find  the  development 
of  the  cerebellum  to  correspond  very  closely  with  the  perfection 
and  variety  of  the  muscular  movements.  The  frog,  for  example, 
is  an  aquatic  reptile  provided  with  anterior  and  posterior  extremi- 
ties ;  but  its  movements,  though  rapid  and  vigorous,  are  exceed- 
ingly simple  in  character,  consisting  of  little  else  than  flexion  and 


TUBERCULA  QUADRIGEMINA.  373 

extension  of  the  posterior  limbs.  The  cerebellum  in  this  animal 
is  exceedingly  small,  compared  with  the  rest  of  the  brain ;  being 
nothing  more  than  a  thin,  narrow  ribbon  of  nervous  matter, 
stretched  across  the  upper  part  of  the  fourth  ventricle.  In  the 
common  turtle  we  have  another  aquatic  reptile,  where  the  move- 
ments of  swimming,  diving,  progression,  &c.,  are  accomplished  by 
the  consentaneous  action  of  both  anterior  and  posterior  extremities, 
and  where  tbe  motions  of  the  head  and  neck  are  also  mucb  more 
varied  than  in  the  frog.  In  this  instance  the  cerebellum  is  very 
much  more  highly  developed  than  in  the  former.  In  the  alli- 
gator, again,  a  reptile  whose  motions,  both  of  the  head,  limbs, 
and  tail,  approach  very  closely  to  those  of  the  quadrupeds,  the 
cerebellum  is  still  larger  in  proportion  to  the  remaining  ganglia  of 
the  encephalon. 

In  the  above  instances,  therefore,  an  evident  correspondence 
exists  between  the  size  of  the  cerebellum  and  the  variety  of  move- 
ment of  which  the  animal  is  capable.  Still,  this  part  of  the  subject 
has  not  yet  been  sufficiently  investigated  to  enable  us  to  say  that 
such  a  correspondence  exists  in  all  cases.  Morbid  alterations  of 
the  cerebellum,  furthermore,  such  as  inflammations,  abscess,  tu- 
mors, &c.,  have  not  always  been  found  to  produce,  in  the  human 
subject,  symptoms  connected  with  a  loss  of  harmony  in  the  volun- 
tary movements.  The  complete  function  of  the  cerebellum.,  ac- 
cordingly, cannot  yet  be  regarded  as  positively  ascertained ;  but  so 
far  as  we  may  rely  on  the  results  of  direct  experiment,  and  on  the 
general  facts  of  comparative  anatomy,  the  most  plausible  opinion  is 
that  of  Flourens,  viz.,  that  the  cerebellum  possesses  the  power  of 
uniting  and  harmonizing  the  action  of  separate  muscles,  so  that 
they  may  assist  each  other  in  the  production  of  varied  and  com- 
plicated movements. 


TUBERCULA  QUADRIGEMINA. 

These  bodies,  notwithstanding  their  small  size,  are  very  important 
in  regard  to  their  function.  They  give  origin  to  the  optic  nerves, 
and  preside,  as  ganglia,  over  the  sense  of  sight;  on  which  account 
they  are  also  known  by  the  name  of  the  "  optic  ganglia."  Their 
development  corresponds  very  closely  with  that  of  the  external 
organs  of  vision.  Thus,  they  are  large  in  fish,  reptiles,  and  birds, 
in  which  the  eyeball  is  for  the  most  part  very  large  in  proportion 


874  •  THE    BEAIN". 

to  the  entire  head ;  and  are  small  in  quadrupeds  and  in  man, 
where  the  eyeball  is,  comparatively  speaking,  of  insignificant  size. 
Direct  experiment  also  shows  the  close  connection  between  the 
tubercula  quadrigemina  and  the  sense  of  sight.  Section  of  the 
optic  nerve  at  any  point  between  the  retina  and  the  tubercles,  pro- 
duces complete  blindness;  and  destruction  of  the  tubercles  them- 
selves has  the  same  effect.  But  if  the  division  be  made  between 
the  tubercles  and  the  cerebrum,  or  if  the  cerebrum  itself  be  taken 
away  while  the  tubercles  are  left  untouched,  vision,  as  we  have 
already  seen,  still  remains.  It  is  the  tubercles,  therefore,  in  which 
the  impression  of  light  is  perceived.  So  long  as  these  ganglia  are 
uninjured  and  retain  their  connection  with  the  eye,  vision  remains. 
As  soon  as  this  connection  is  cut  off,  or  the  ganglia  themselves  are 
injured,  the  power  of  vision  is  destroyed. 

The  tubercula  quadrigemina  not  only  serve  as  nervous  centres 
for  the  perception  of  light,  but  a  reflex  action  also  takes  place 
through  them,  by  which  the  quantity  of  light  admitted  to  the  eye 
is  regulated  to  suit  the  sensibility  of  the  pupil.  In  darkness  and 
in  twilight,  or  wherever  the  light  is  obscure  and  feeble,  the  pupil 
is  enlarged  by  a  relaxation  of  its  circular  fibres,  so  as  to  admit  as 
large  a  quantity  of  light  as  possible.  On  first  coming  into  a  dark 
room,  accordingly,  everything  is  nearly  invisible ;  but  gradually, 
aS  the  pupil  dilates  and  as  more  light  is  admitted,  objects  begin  to 
show  themselves  with  greater  distinctness,  and  at  last  we  can  see 
tolerably  well  in  a  place  where  we  were  at  first  unable  to  perceive 
a  single  object.  On  the  other  hand,  when  the  eye  is  exposed  to 
an  unusually  brilliant  light,  the  pupil  contracts  and  shuts  out  so 
much  of  it  as  would  be  injurious  to  the  retina. 

The  above  is  a  reflex  action,  in  which  the  impression  received  by 
the  retina  is  transmitted  along  the  optic  nerve  to  the  tubercula 
quadrigemina.  From  the  tubercles,  a  motor  impulse  is  then  sent 
out  through  the  motor  nerves  of  the  eye  and  the  filaments  dis- 
tributed to  the  iris,  and  a  contraction  of  the  pupil  takes  place  in 
consequence.  The  optic  nerves  act  here  as  sensitive  fibres,  which 
convey  the  impression  from  the  retina  to  the  ganglion;  and  if 
they  be  irritated  in  any  part  of  their  course  with  the  point  of  a 
needle,  the  result  is  a  contraction  of  the  pupil.  This  influence  is 
not  communicated  directly  from  the  nerve  to  the  iris,  but  is  first 
sent  inward  to  the  tubercles,  to  be  afterward  reflected  outward  by 
the  motor  nerves.  So  long  as  the  eyeball  remains  in  connection 
with  the  brain,  mechanical  irritation  of  the  optic  nerve,  as  we  have 


TUBEKCULA    QUADRIGEMINA. 


375 


shown  above,  causes  contraction  of  the  pupil;  but  if  the  nerve  be 
divided,  and  the  extremity  which  remains  in  connection  with  the 
eyeball  subjected  to  irritation,  no  effect  upon  the  pupil  is  produced. 
The  anatomical  arrangement  of  the  optic  nerves,  and  the  connec- 
tions of  the  optic  tubercles,  are  modified  in  a  remarkable  degree  in 
different  animals,  to  correspond  with  the  position  of  the  two  eyes. 
In  fish,  for  example,  the  eyes  are  so  placed,  on  opposite  sides  of  the 
head,  that  their  axes  cannot  be  brought  into  parallelism  with  each 
other,  and  the  two  eyes  can  never  be  directed  together  to  the  same 
object.  In  these  animals,  the  optic  nerves  cross  each  other  at  the 
base  of  the  brain  without  any  intermixture  of  their  fibres;  that 
from  the  right  optic  tubercle  passing  to  the  left  eye,  and  that  from 
the  left  optic  tubercle  passing  to  the  right  eye.  (Fig.  148.)  The  two 
nervous  cords  are  here  totally  distinct  from  each  other  throughout 
their  entire  length ;  and  are  only  connected,  at  the  point  of  cross- 
ing, by  intervening  areolar  tissue.  Impressions  made  on  the  right 
eye  must  therefore  be  perceived  on  the  left  side  of  the  brain;  while 
those  which  enter  the  left  eye  are  conveyed  to  the  right  side  of 
the  brain. 


Fig.  143. 


Fig.  144. 


Inferior  Surface  of  Brain 
OF  Cod. — 1.  Eight  optic  nerve.  2.  Left 
optic  nerve.  3.  Right  optic  tubercle.  4. 
Left  optic  tubercle.  6,  6.  Hemispheres. 
7.  Medulla  oblongata. 


Infkrior  Surface  of  Brain  op 
Fowl. — \.  Right  optic  nerve.  2.  Left  optic 
nerre  3.  Right  optic  tubercle.  4.  Left 
optic  tubercle.  6,  6.  Hemispheres.  7.  Me- 
dulla oblongata. 


In  birds,  also,  the  axes  of  the  two  eyes  are  so  widely  divergent 
that  an  object  cannot  be  distinctly  in  focus  for  both  of  them  at  the 


376 


THE    BRAIlSr. 


same  time.  The  optic  nerves  are  here  united,  and  apparently  sol- 
dered together,  at  their  point  of  crossing;  but  the  decussation  of 
their  fibres  is  nevertheless  complete.  (Fig.  144.)  The  nervous  fila- 
ments coming  from  the  left  side  pass  altogether  over  to  the  right ; 
and  those  coming  from  the  right  side  pass  over  to  the  left.  The 
result  of  direct  experiment  on  the  crossed  action  of  the  tubercles 
in  these  animals  corresponds  with  the  anatomical  arrangement  of 
the  nervous  fibres.  If  one  of  the  optic  tubercles  be  destroyed  in 
the  pigeon,  complete  blindness  is  at  once  produced  in  the  eye  of 
the  opposite  side;  but  vision  remains  unimpaired  in  the  eye  of  the 
same  side  with  the  injury. 

In  the  human  subject,  on  the  other  hand,  where  the  visual  axes 
are  parallel,  and  where  both  eyes  are  simultaneously  directed  to  the 
same  object,  the  optic  nerves  decussate  with  each  other  in  such  a 
manner  as  to  form  a  connection  between  the  two  opposite  sides,  as 
well  as  between  each  tubercle  and  retina  of  the  same  side.  (Fig. 
145.)    This  decussation,  which  is  somewhat  complicated,  takes  place 

Fig.  145. 


CotTRSE  OP  Optic  Nerves  in  Man. — 1,  2.  Eight  and  left  eyeballs.     3.  Decussation  of  optic 
nerves.    4,  i.  Tubercula  quadrigemina. 

in  the  following  manner.     From  each  optic  tubercle  three  difi'erent 
bundles  or  "  tracts"  of  nervous  fibres  are  given  ofi".     One  set  passes 


TUBER    ANNULARE.  377 

across  transversely  at  the  point  of  decussation,  and  turning  back- 
ward, terminates  in  the  tubercle  of  the  opposite  side;  another,  cross 
ing  diagonally,  continues  onward  to  the  opposite  eyeball;  while  a 
third  passes  directly  forward  to  the  eyeball  of  the  same  side.  A 
fourth  set  of  fibres,  still,  passes  across,  in  front  of  the  decussation, 
from  the  retina  of  one  eye  to  that  of  the  opposite  side.  We  have, 
therefore,  by  this  arrangement,  the  two  retinae,  as  well  as  the  two 
optic  tubercles,  connected  with  each  other  by  commissural  fibres ; 
while  each  tubercle  is,  at  the  same  time,  connected  both  with  its 
own  retina  and  with  that  of  the  opposite  side.  It  is  undoubtedly 
owing  to  these  connections  that  when,  in  the  human  subject,  the  eyes 
are  directed  in  their  proper  axes,  the  two  retinae,  as  well  as  the  two 
optic  tubercles,  act  as  a  single  organ.  Vision  is  single,  therefore, 
though  there  are  two  images  upon  the  retinae.  Double  vision 
occurs  only  when  the  eyeballs  are  turned  out  of  their  proper  direc- 
tion, so  that  the  parallelism  of  their  axes  is  lost,  and  the  image  no 
longer  falls  upon  corresponding  parts  of  the  two  retinae. 


TUBER  ANNULARE. 

The  collection  of  gray  matter  imbedded  in  the  deeper  portions 
of  the  tuber  annulare  occupies  a  situation  near  the  central  part  of 
the  brain,  and  lies  directly  in  the  course  of  the  ascending  fibres  of 
the  anterior  and  posterior  columns  of  the  cord.  This  ganglion  is 
immediately  connected  with  the  functions  of  sensation  and  volun- 
tary motion.  We  have  already  seen  that  these  functions  are  not 
destroyed  by  taking  away  the  cerebrum,  and  that  they  also  remain 
after  removal  of  the  cerebellum.  According  to  the  experiments  of 
Longet,  even  after  complete  removal  of  the  olfactory  ganglia,  the 
cerebrum,  cerebellum,  optic  tubercles,  corpora  striata  and  optic 
thalami,  and  when  nothing  remains  in  the  cavity  of  the  cranium  but 
the  tuber  annulare  and  the  medulla  oblongata,  the  animal  is  still 
sensitive  to  external  impressions,  and  will  still  endeavor  by  volun- 
tary movements  to  escape  from  a  painful  irritation.  The  same 
observer  has  found,  however,  that  as  soon  as  the  ganglion  of  the 
tuber  annulare  is  broken  up,  all  manifestations  of  sensation  and 
volition  cease,  and  even  consciousness  no  longer  appears  to  exist. 
The  only  movements  which  then  follow  external  irritation  are  the 
occasional  convulsive  motions  which  are  due  to  reflex  action  of  the 
spinal  cord,  and  which  may  be  readily  distinguished  from  those  of  a 


378  THE    BRAIN. 

voluntary  character.  The  animal,  under  these  circumstances,  is  to 
all  appearances  reduced  to  the  condition  of  a  dead  body,  except  for 
the  movements  of  respiration  and  circulation,  which  still  go  on  for 
a  certain  time.  The  tuber  annulare  must  therefore  be  regarded  as 
the  ganglion  by  which  impressions,  conveyed  inward  through  the 
nerves,  are  first  converted  into  conscious  sensations;  and  in  which 
the  voluntary  impulses  originate,  which  stimulate  the  muscles  to 
contraction. 

We  must  carefully  distinguish,  however,  in  this  respect,  a  simple 
sensation  from  the  ideas  to  which  it  gives  origin  in  the  mind,  and 
the  mere  act  of  volition  from  the  train  of  thought  which  leads  to 
it.  Both  these  purely  mental  operations  take  place,  as  we  have 
seen,  in  the  cerebrum ;  for  mere  sensation  and  volition  may  exist 
independently  of  any  intellectual  action,  as  they  may  exist  after 
the  cerebrum  has  been  destroyed.  A  sensation  may  be  felt,  for 
example,  without  our  having  the  power  of  thoroughly  appreciating 
it,  or  of  referring  it  to  its  proper  source.  This  condition  is  often 
experienced  in  a  state  of  deep  sleep,  when,  the  body  being  exposed 
to  cold,  or  accidentally  placed  in  a  constrained  position,  we  feel  a 
sense  of  suffering,  without  being  able  to  understand  its  cause.  We 
may  even,  under  such  circumstances,  execute  voluntary  movements 
to  escape  the  cause  of  annoyance ;  but  these  movements,  not  being 
directed  by  any  active  intelligence,  fail  of  accomplishing  their  ob- 
ject. We  therefore  remain  in  a  state  of  discomfort  until,  on  awak- 
ening, the  activity  of  the  reason  and  judgment  is  restored,  when 
the  offending  cause  is  at  once  removed. 

We  distinguish,  then,  between  the  simple  power  of  sensation, 
and  the  power  of  fully  appreciating  a  sensitive  impression  and  of 
drawing  a  conclusion  from  it.  We  distinguish  also  between  the 
intellectual  process  which  leads  us  to  decide  upon  a  voluntary 
movement,  and  the  act  of  volition  itself.  The  former  must  precede, 
the  latter  must  follow.  The  former  takes  place,  so  far  as  experi- 
ment can  show,  in  tlie  cerebral  hemispheres ;  the  latter,  in  the  gan- 
glion of  the  tuber  annulare. 


MEDULLA  OBLONGATA. 

The  last  remaining  ganglion  of  the  encephalon  is  that  of  the 
medulla  oblongata.  This  ganglion,  it  will  be  remembered,  is 
imbedded  in  the  substance  of  the  restiform  body,  occupying  the 


MEDULLA    OBLONGATA.  379 

lateral  and  posterior  portions  of  the  medulla,  at  the  point  of  origin 
of  the  pneumogastric  nerves.  This  portion  of  the  brain  has  long 
been  known  to  be  particularly  essential  to  the  preservation  of  life ; 
so  that  it  has  received  the  name  of  the  "  vital  point,"  or  the 
"  vital  knot."  All  the  other  parts  of  the  brain  may  be  injured  or 
removed,  as  we  have  already  seen,  without  the  immediate  and  ne- 
cessary destruction  of  life ;  but  so  soon  as  the  medulla  oblongata  is 
broken  up,  and  its  ganglion  destroyed,  respiration  ceases  instanta- 
neously, and  the  circulation  also  soon  comes  to  an  end.  Removal 
of  the  medulla  oblongata  produces,  therefore,  as  its  immediate  and 
direct  result,  a  stoppage  of  respiration;  and  death  takes  place  prin- 
cipally as  a  consequence  of  this  fact. 

Flourens  and  Longet  have  determined,  with  considerable  accu- 
racy, the  precise  limits  of  this  vital  spot  in  the  medulla  oblongata. 
Flourens  ascertained  that  in  rabbits  it  extended  from  just  above 
the  origin  of  the  pneumogastric  nerve,  to  a  level  situated  three  lines 
and  a  half  below  this  origin.  In  larger  animals,  its  extent  is  pro- 
portionately increased.  Longet  ascertained,  furthermore,  that  the 
properties  of  the  medulla  were  not  the  same  throughout  its  entire 
thickness ;  but  that  its  posterior  and  anterior  parts  might  be  de- 
stroyed with  comparative  impunity,  the  peculiarly  vital  spot  being 
confined  to  the  intermediate  portions.  This  vital  point  accordingly 
is  situated  in  the  layer  of  gray  matter,  imbedded  in  the  thickness 
of  the  restiform  bodies,  which  has  been  previously  spoken  of  as 
giving  origin  to  the  pneumogastric  nerves. 

The  precise  nature  of  the  connection  between  this  ganglion  and 
the  function  of  respiration  may  be  described  as  follows.  The 
movements  of  respiration,  which  follow  each  other  with  incessant 
regularity  through  the  whole  period  of  life,  are  not  voluntary 
movements.  We  may,  to  a  certain  extent,  hasten  or  retard  them 
at  will,  but  our  power  over  them,  even  in  this  respect,  is  extremely 
limited;  and  in  point  of  fact  they  are  performed,  during  the  greater 
part  of  the  time,  in  a  perfectly  quiet  and  regular  manner,  without 
our  volition  and  even  without  our  consciousness.  They  continue 
uninterrupted  through  the  deepest  slumber,  and  even  in  a  condition 
of  insensibility  from  accident  or  disease. 

These  movements  are  the  result  of  a  reflex  action  taking  place 
through  the  medulla  oblongata.  The  impression  which  gives  rise 
to  them  originates  principally  in  the  lungs,  from  the  accumulation 
of  carbonic  acid  in  the  pulmonary  vessels  and  air-cells,  is  trans- 
mitted by  the  pneumogastric  nerves  to  the  medulla,  and  is  thence 


380  THE    BRAIISr. 

reflected  back  along  the  motor  nerves  to  the  respiratory  muscles. 
These  muscles  are  then  called  into  action,  producing  an  expansion 
of  the  chest.  The  impression  so  conveyed  to  the  medulla  is  usually 
unperceived  by  the  consciousness.  It  is  generally  converted  directly 
into  a  motor  impulse,  without  attracting  our  attention  or  giving 
rise  to  any  conscious  sensation.  Respiration,  accordingly,  goes  on 
perfectly  well  without  our  interference  and  without  our  knowledge. 
The  nervous  impression,  however,  conveyed  to  the  medulla,  though 
usually  imperceptible,  may  be  made  evident  at  any  time  by  volun- 
tarily suspending  the  respiration.  As  the  carbonic  acid  begins  to 
accumulate  in  the  blood  and  in  the  lungs,  a  peculiar  sensation  makes 
itself  felt,  which  grows  stronger  and  stronger  with  every  moment, 
and  impels  us  to  recommence  the  movements  of  inspiration.  This 
peculiar  sensation,  entirely  different  in  character  from  any  other,  is 
desio'nated  by  the  French  under  the  name  of  "  besoin  de  respirer." 
It  becomes  more  urgent  and  distressing,  the  longer  respiration  is 
suspended,  until  finally  the  impulse  to  expand  the  chest  can  no 
longer  be  resisted  by  any  effort  of  the  will. 

During  ordinary  respiration,  therefore,  each  inspiratory  move- 
ment is  excited  by  the  partial  vitiation  of  the  air  contained  in  the 
lungs.  As  soon  as  a  new  supply  has  been  inhaled,  the  impulse  to 
respire  is  satisfied,  the  muscles  relax,  and  the  chest  collapses.  In 
a  few  seconds  the  previous  condition  recurs  and  the  same  move- 
ments are  repeated,  producing  in  this  way  a  regular  alternation  of 
inspirations  and  expirations. 

Since  the  movements  of  respiration  are  performed  partly  by  the 
diaphragm  and  partly  by  the  intercostal  muscles,  they  will  be 
differently  modified  by  injuries  of  the  nervous  system,  according  to 
the  spot  at  which  the  injury  is  inflicted.  If  the  spinal  cord,  for 
example,  be  divided  or  compressed  in  the  lower  part  of  the  neck, 
all  the  intercostal  muscles  will  be  necessarily  paralyzed,  and  respi- 
ration will  then  be  performed  entirely  by  the  diaphragm.  The 
chest  in  these  cases  remaining  motionless,  and  the  abdomen  alone 
rising  and  falling  with  the  movements  of  the  diaphragm,  such 
respiration  is  called  "  abdominal"  or  "  diaphragmatic"  respiration. 
It  is  a  common  symptom  of  fracture  of  the  spine  in  the  lower 
cervical  region.  If  the  phrenic  nerve,  on  the  other  hand,  be 
divided,  the  diaphragm  will  be  paralyzed,  and  respiration  will  then 
be  performed  altogether  by  the  rising  and  falling  of  the  ribs.  It 
is  then  called  "thoracic"  or  "costal"  respiration.  If  the  injury 
inflicted  upon  the  spinal  cord  be  above  the  origin  of  the  second 


MEDULLA    OBLONGATA.  381 

and  third  cervical  nerves,  both  the  phrenic  and  intercostal  nerves 
are  at  once  paralyzed,  and  death  necessarily  takes  place  from  suf; 
focation.  The  attempt  at  respiration,  however,  still  continues  in 
these  cases,  showing  itself  by  ineffectaal  inspiratory  movements  of 
the  mouth  and  nostrils.  Finally,  if  the  medulla  itself  be  broken 
up  by  a  steel  instrument  introduced  through  the  foramen  magnum, 
so  as  to  destroy  the  nervous  centre  in  which  the  above  reflex  action 
takes  place,  both  the  power  and  the  desire  to  breathe  are  at  once 
taken  away.  No  attempt  is  made  at  inspiration,  there  is  no 
struggle,  and  no  appearance  of  suffering.  The  animal  dies  simply 
by  a  want  of  aeration  of  the  blood,  which  leads  in  a  few  moments 
to  an  arrest  of  the  circulation. 

It  is  owing  to  the  above  action  of  the  medulla  oblongata  that  in- 
juries of  this  part  are  so  promptly  and  constantly  fatal.  When  the 
"  neck  is  broken,"  as  in  hanging  or  by  sudden  falls  upon  the  head,  a 
rupture  takes  place  of  the  transverse  ligament  of  the  atlas;  the  head, 
together  with  the  first  cervical  vertebra,  is  allowed  to  slide  forward, 
and  the  medulla  is  compressed  between  the  odontoid  process  of  the 
axis  in  front  and  the  posterior  part  of  the  arch  of  the  atlas  behind. 
In  cases  of  apoplexy,  where  any  part  of  the  hemispheres,  corpora 
striata,  or  optic  thalami,  is  the  seat  of  the  hemorrhage,  the  patient 
generally  lives  at  least  twelve  hours ;  but  if  the  hemorrhage  take 
place  into  the  medulla  itself,  or  at  the  base  of  the  brain  in  its  imme- 
diate neighborhood,  so  as  to  compress  its  substance,  death  follows 
instantaneously,  and  by  the  same  mechanism  as  where  the  medulla 
is  intentionally  destroyed. 

An  irregularity  or  want  of  correspondence  in  the  movements  of 
respiration  is  accordingly  found  to  be  one  of  the  most  threatening 
of  all  symptoms  in  affections  of  the  brain.  A  disturbance  or  sus- 
pension of  the  intellectual  powers  does  not  indicate  necessarily  any 
immediate  danger  to  life.  Even  sensation  and  volition  may  be  im- 
paired without  serious  and  direct  injury  to  the  organic  functions. 
These  symptoms  only  indicate  the  threatening  progress  of  the  dis- 
ease, and  show  that  it  is  gradually  approaching  the  vital  centre.  It 
is  common  to  see,  however,  as  the  medulla  itself  begins  to  be  impli- 
cated, a  paralysis  first  showing  itself  in  the  respiratory  movements 
of  the  nostrils  and  lips,  while  those  of  the  chest  and  abdomen  still 
go  on  as  usual.  The  cheeks  are  then  drawn  in  with  every  inspira- 
tion and  puffed  out  sluggishly  with  every  expiration,  the  nostrils 
themselves  sometimes  participating  in  these  unnatural  movements. 
A  still  more  threatening  symptom,  and  one  which  frequently  pre- 


382  THE    BEAIN. 

cedes  death,  is  an  irregular,  hesitating  respiration,  which  sometimes 
attracts  the  attention  of  the  physician,  even  before  the  remaining 
cerebral  functions  are  seriously  impaired.  These  phenomena  de- 
pend on  the  connection  between  the  respiratory  movements  and  the 
reflex  action  of  the  medulla  oblongata. 

We  have  now,  in  studying  the  functions  of  various  parts  of  the 
cerebro-spinal  system,  become  familiar  with  three  difl'erent  kinds  of 
reflex  action. 

The  first  is  that  of  the  spinal  cord.  Here,  there  is  no  proper 
sensation  and  no  direct  consciousness  of  the  act  which  is  performed. 
It  is  simply  a  nervous  impression,  coming  from  the  integument, 
and  transformed  by  the  gray  matter  of  the  spinal  cord  into  a  motor 
impulse  destined  for  the  muscles.  This  action  will  take  place  after 
the  removal  of  the  hemispheres  and  the  abolition  of  consciousness, 
as  well  as  in  the  ordinary  condition.  The  respiratory  action  of  the 
medulla  oblongata  is  of  the  same  general  character ;  that  is,  it  is 
not  necessarily  connected  with  either  volition  or  consciousness. 
The  only  peculiarity  in  this  instance  is  that  the  original  nervous 
impression  is  of  a  special  character,  and  its  influence  is  finally 
exerted  upon  a  special  muscular  apparatus.  Actions  of  this  nature 
are  termed,  par  excellence,  reflex  actions. 

The  second  kind  of  reflex  action  takes  place  in  the  tuber  annu- 
lare. Here  the  nervous  impression,  which  is  conveyed  inward 
from  the  integument,  instead  of  stopping,at  the  spinal  cord,  passes 
onward  to  the  tuber  annulare,  where  it  first  gives  rise  to  a  con- 
scious sensation ;  and  this  sensation  is  immediately  followed  by  a 
voluntary  act.  Thus,  if  a  crumb  of  bread  fall  into  the  larynx,  the 
sensation  produced  by  it  excites  the  movement  of  coughing.  The 
sensations  of  hunger  and  thirst  excite  a  desire  for  food  and  drink. 
The  sexual  impulse  acts  in  precisely  the  same  manner ;  the  percep- 
tion of  particular  objects  giving  rise  immediately  to  special  desires 
of  a  sexual  character. 

It  will  be  observed,  in  these  instances,  that  in  the  first  place, 
the  nervous  sensation  must  be  actually  perceived,  in  order  to  pro- 
duce its  effect;  and  in  the  second  place  that  the  action  which 
follows  is  wholly  voluntary  in  character.  But  the  most  important 
peculiarity,  in  this  respect,  is  that  the  voluntary  impulse  follows 
directly  upon  the  receipt  of  the  sensation.  There  is  no  intermediate 
reasoning  or  intellectual  process.  We  do  not  cough  because  we 
know  that  this  is  the  most  effectual  way  to  clear  the  larynx ;  but 
simply  because  we  are  impelled  to  do  so  by  the  sensation  which  is 


MEDULLA    OBLONGATA.  383 

felt  at  the  time.  We  do  not  take  food  or  drink  because  we  know- 
that  they  are  necessary  to  support  life,  much  less  because  we  under- 
stand the  mode  in  which  they  accomplish  this  object ;  but  merely 
because  we  desire  them  whenever  we  feel  the  sensations  of  hunger 
and  thirst. 

All  actions  of  this  nature  are  termed  insiinctive.  They  are  volun- 
tary in  character,  but  are  performed  blindly ;  that  is,  without  any 
idea  of  the  ultimate  object  to  be  accomplished  by  them,  and  simply 
in  consequence  of  the  receipt  of  a  particular  sensation.  Accord- 
ingly experience,  judgment,  and  adaptation  have  nothing  to  do  with 
these  actions.  Thus  the  bee  builds  his  cell  on  the  plan  of  a  mathe- 
matical figure,  without  performing  any  mathematical  calculation. 
The  silkworm  wraps  himself  in  a  cocoon  of  his  own  spinning, 
certainly  without  knowing  that  it  is  to  afford  him  shelter  during 
the  period  of  his  metamorphosis.  The  fowl  incubates  her  eggs 
and  keeps  them  at  the  proper  temperature  for  development,  simply 
because  the  sight  of  them  creates  in  her  a  desire  to  do  so.  The 
habits  of  these  animals,  it  is  true,  are  so  arranged  by  nature,  that 
such  instinctive  actions  are  always  calculated  to  accomplish  an 
ultimate  object.  But  this  calculation  is  not  made  by  the  animal 
himself,  and  does  not  form  any  part  of  his  mental  operations. 
There  is  consequently  no  improvement  in  the  mode  of  performing 
such  actions,  and  but  little  deviation  under  a  variety  of  circum- 
stances. 

The  third  kind  of  reflex  action  requires  the  co-operation  of  the 
hemispheres.  Here,  the  nervous  impression  is  not  only  conveyed 
to  the  tuber  annulare  and  converted  into  a  sensation,  but,  still 
following  upward  the  course  of  the  fibres  to  the  cerebrum,  it  there 
gives  rise  to  a  special  train  of  ideas.  We  understand  then  the 
external  source  of  the  sensation,  the  manner  in  which  it  is  calcu- 
lated to  affect  us,  and  how  by  our  actions  we  may  turn  it  to  our 
advantage  or  otherwise.  The  action  which  follows,  therefore,  in 
these  cases,  is  not  simply  voluntary,  but  reasonable.  It  does  not 
depend  directly  upon  the  external  sensation,  but  upon  an  intellec- 
tual process  which  intervenes  between  the  sensation  and  the  voli- 
tion. These  actions  are  distinguished,  accordingly,  by  a  character 
of  definite  contrivance,  and  a  conscious  adaptation  of  means  to 
ends ;  characteristics  which  do  not  belong  to  any  other  operations 
of  the  nervous  system. 

The  possession  of  this  kind  of  intelligence  and  reasoning  power 
is  not  confined  to  the  human  species.     We  have  already  seen  that 


384:  THE    BRAIN. 

there  are  many  purely  instinctive  actions  in  man,  as  well  as  in 
animals.  It  is  no  less  true  that  in  the  higher  animals  there  is  often 
the  same  exercise  of  reasoning  power  as  in  man.  The  degree  of 
this  power  is  much  less  in  them  than  in  him,  but  its  nature  is  the 
same.  Whenever,  in  an  animal,  we  see  any  action  performed  with 
the  evident  intention  of  accomplishing  a  particular  object,  to  which 
it  is  properly  adapted,  such  an  act  is  plainly  the  result  of  reason- 
ing powers,  not  essentially  different  from  our  own.  The  establish- 
ment of  sentinels  by  gregarious  animals,  to  warn  the  herd  of  the 
approach  of  danger,  the  recollection  of  punishment  inflicted  for  a 
particular  action,  and  the  subsequent  avoidance  or  concealment  of 
that  action,  the  teachability  of  many  animals,  and  their  capacity  of 
forming  new  habits  or  of  improving  the  old  ones,  are  all  instances 
of  the  same  kind  of  intellectual  power,  and  are  quite  different  from 
instinct,  strictly  speaking.  It  is  this  faculty  which  especially  pre- 
dominates over  the  others  in  the  higher  classes  of  animals,  and 
which  finally  attains  its  maximum  of  development  in  the  human 
species. 


CRANIAL    NERVES.  385 


CHAPTER     V. 

THE   CRANIAL   NERVES. 

In  examining  the  cranial  nerves,  we  shall  find  that  although  they 
at  first  seem  quite  different  in  their  distribution  and  properties 
from  the  spinal  nerves,  yet  they  are  in  reality  arranged  for  the 
most  part  on  the  same  plan,  and  may  be  studied  in  a  similar 
manner. 

At  the  outset,  however,  we  find  that  there  are  three^  of  the 
cranial  nerves,  commonly  so  called,  which  must  be  arranged  in  a 
class  by  themselves ;  since  they  have  no  character  in  common  with 
the  other  nerves  originating  either  from  the  brain  or  the  spinal  cord. 
These  are  the  three  nerves  of  special  sense;  viz.,  the  Olfactory,  Optic, 
and  Auditory.  They  are,  properly  speaking,  not  so  much  nerves 
as  commissures,  connecting  different  parts  of  the  encephalic  mass 
with  each  other.  They  are  neither  sensitive  nor  motor,  in  the 
ordinary  meaning  of  these  terms;  but  are  capable  of  conveying 
only  the  special  sensation  characteristic  of  the  organ  with  which 
they  are  connected. 

Olfactory  Nerves. — We  have  already  described  the  so-called 
olfactory  nerves  as  being  in  reality  commissures,  connecting  the 
olfactory  ganglia  with  the  central  parts  of  the  brain.  The  masses 
situated  upon  the  cribriform  plate  of  the  ethmoid  bone  are  com- 
posed of  gray  matter;  and  even  the  filaments  which  they  send 
outward  to  be  distributed  in  the  Schneiderian  mucous  membrane, 
are  gray  and  gelatinous  in  their  texture,  and  quite  different  from 
the  fibres  of  ordinary  nerves.  The  olfactory  nerves  are  not  very 
well  adapted  for  direct  experiment.  It  is,  however,  at  least  certain 
with  regard  to  them  that  they  serve  to  convey  the  special  sensation 
of  smell;  that  their  mechanical  irritation  does  not  give  rise  to 
either  pain  or  convulsions;  and  that  finally  their  destruction, 
together  with  that  of  the  olfactory  ganglia,  does  not  occasion  any 
paralysis  nor  loss  of  ordinary  sensibility. 
25 


386  THE    CEANIAL    NERVES. 

Optic  Nerves. — We  have  already  given  some  account  of  these 
nerves  and  their  decussations,  in  connection  with  the  history  of  the 
tubercula  quadrigemina.  They  consist  of  rounded  bundles  of 
white  fibres,  running  between  the  tubercles  and  the  retinae.  As 
the  retinae  themselves  are  membranous  expansions  consisting  mostly 
of  vesicular  or  cellular  nervous  matter,  the  optic  nerves,  or  "tracts," 
must  be  regarded  as  commissures  connecting  the  retinee  with  the 
tubercles.  We  have  also  seen  that  they  serve,  by  some  of  their 
fibres,  to  connect  the  two  retinas  with  each  other,  as  well  as  the  two 
tubercles  with  each  other. 

The  optic  nerves  convey  only  the  special  impression  of  light  from 
without  inward,  and  give  origin  to  the  reflex  action  of  the  optic 
tubercles,  by  which  the  pupil  is  made  to  contract.  According  to 
Lono-et,  the  optic  nerves  are  absolutely  insensible  to  pain  throughout 
their  entire  length.  When  a  galvanic  current  is  passed  through 
the  eyeball,  or  when  the  retina  is  touched  in  operations  upon  the 
eye,  the  irritation  has  been  found  to  produce  the  impression  of 
luminous  sparks  and  flashes,  instead  of  an  ordinary  painful  sensation. 
The  impression  of  colored  rings  or  spots  may  be  easily  produced 
by  compressing  the  eye  in  particular  directions;  and  a  sudden 
stroke  upon  the  eyeball  will  often  give  rise  to  an  apparent  dis- 
charge of  brilliant  sparks.  Division  of  the  optic  nerves  produces 
complete  blindness,  but  does  not  destroy  ordinary  sensibility  in  any 
part  of  the  eye,  nor  occasion  any  muscular  paralysis. 

Auditory  Nerves. — The  nervous  expansion  in  the  cavity  of 
the  internal  ear  contains,  like  the  retina,  vesicles  or  cells  as  well  as 
fibres ;  and  the  auditory  nerves  are  therefore  to  be  regarded,  like 
the  optic  and  olfactory,  as  commissural  in  their  character.  They 
are  also,  like  the  preceding,  destitute  of  ordinary  sensibility.  Ac- 
cording to  Longet,  they  may  be  injured  or  destroyed  without  giving 
rise  to  any  sensation  of  pain.  They  serve  to  convey  to  the  brain 
the  special  sensation  of  sound,  and  seem  incapable  of  transmitting 
any  other.  Longet'  relates  an  experiment  performed  by  Volta  in 
which,  by  passing  a  galvanic  current  through  the  ears,  the  observer 
experienced  the  sensation  of  an  interrupted  hissing  noise,  so  long 
as  th.e  connection  of  the  wires  was  maintained.  Inflammations 
within  the  ear,  or  in  its  neighborhood,  are  often  accompanied  by 
the  perception  of   various  noises,  like  the  ringing  of  bells,  the 

'  Traite  de  Physiologic,  vol.  ii.  p.  286. 


THE    CRANIAL    NERVES.  o»7 

washing  of  the  waves,  the  humming  of  insects;  sounds  which  have 
no  external  existence,  but  which  are  simulated  by  the  morbid  irri- 
tation of  the  auditory  nerve. 

It  is  evident  from  the  facts  detailed  above  that  the  nerves  of 
special  sense  are  neither  motor  nor  sensitive,  properly  speaking; 
and  that  they  are  distinct  in  their  nature  from  the  ordinary  spinal 
nerves. 

The  remainder  of  the  cranial  nerves,  however,  have  no  such 
essential  peculiarities.  Some  of  them  are  exclusively  motor  in 
character,  others  exclusively  sensitive;  while  most  of  them  exhibit 
the  two  properties  to  a  certain  extent,  as  mixed  nerves.  They 
may  be  conveniently  arranged  in  three  pairs,  according  to  the 
regions  in  which  they  are  distributed,  corresponding  very  closely 
with  the  motor  and  sensitive  roots  of  the  spinal  nerves.  According 
to  such  a  plan,  the  arrangement  of  the  cranial  nerves  would  be  as 
follows : — 


Ck 

vxiAL  Nerves. 

Nerves 

of  Special  Sense. 

1.  Olfactory. 

2.  Optic.     3.  Auditory. 

Motor  Nerves. 

Distributed  to                       Seasitive  Nerves. 

Motor  oculi  com. 

■ 

Patheticus 

Face.                  Large  root  of  5  th 

1st  PAIR.      • 

Motor  oc.  externus 

Small  root  of  5th  pai 

r 

L  Facial 

, 

2d  PAIR. 

Sublingual 

Tongue.             Glosso-pharyngeal 

3d   PAIR. 

Spinal  accessory 

Neck,  &c.          Pneumogastric. 

The  above  arrangement  of  the  cranial  nerves  is  not  absolutely 
perfect  in  all  its  details.  Thus,  while  the  sublingual  supplies  the 
muscles  of  the  tongue  alone,  the  glosso-pharyngeal  sends  part  of 
its  sensitive  fibres  to  the  tongue  and  part  to  the  pharynx;  and 
while  the  large  root  of  the  5th  pair  is  mostly  distributed  in  the 
face,  one  of  its  branches,  viz.,  the  gustatory,  is  distributed  to  the 
tongue.  Notwithstanding  these  irregularities,  however,  the  above 
division  of  the  cranial  nerves  is  in  the  main  correct,  and  will  be 
found  extremely  useful  as  an  assistant  in  the  study  of  their  func- 
tions. 

There  is  no  impropriety,  moreover,  in  regarding  all  the  motor 
branches  distributed  upon  the  face  as  one  nerve;  since  even  the 
anterior  roots  of  the  spinal  nerves  originate  from  the  spinal  cord, 
each  by  several  distinct  filaments,  which  are  associated  into  a  single 
bundle  only  at  a  certain  distance  from  their  point  of  origin.     The 


388  THE    CRANIAL    NERVES. 

mere  fact  that  two  nerves  leave  the  cavity  of  the  cranium  by  the 
same  foramen  does  not  indicate  that  they  have  the  same  or  even  a 
similar  function.  Thus  the  facial  and  auditory  both  escape  from 
the  cavity  of  the  cranium  by  the  foramen  auditorium  internum,  and 
yet  we  do  not  hesitate  to  regard  them  as  entirely  distinct  in  their 
nature  and  functions.  It  is  the  ultimate  distribution  of  a  nerve, 
and  not  its  course  through  the  bones  of  the  skull,  that  indicates 
its  physiological  character  and  position.  For  while  the  ultimate 
distribution  of  any  particular  nerve  is  always  the  same,  its  arrange- 
ment as  to  trunks  and  branches  may  vary,  in  different  species 
of  animals,  with  the  anatomical  arrangement  of  the  bones  of  the 
skull.  This  is  well  illustrated  by  a  fact  first  pointed  out  by  Dr. 
Jeffries  Wyman^  in  the  anatomy  of  the  nervous  system  of  the 
bullfrog.  In  this  animal,  both  the  facial  nerve  and  motor  oculi 
externus,  instead  of  arising  as  distinct  nerves,  are  actually  given 
off  as  branches  of  the  5th  pair ;  while  their  ultimate  distribution  is 
the  same  as  in  other  animals.  All  the  motor  and  sensitive  nerves 
distributed  to  the  face  are  accordingly  to  be  regarded  as  so  many 
different  branches  of  the  same  trunk;  varying  sometimes  in  their 
course,  but  always  the  same  in  their  ultimate  distribution. 


MOTOR  NERVES. 

The  motor  nerves  of  the  head  are  in  all  respects  identical  in  their 
properties  with  the  anterior  roots  of  the  spinal  nerves.  For,  in 
the  first  place,  they  are  distributed  to  muscles,  and  not  to  the 
inteo-ument  or  to  mucous  membranes;  secondly,  their  division 
causes  muscular  paralysis;  and  thirdly,  mechanical  irritation  ap- 
plied at  their  origin  produces  muscular  contraction  in  the  parts  to 
which  they  are  distributed,  but  does  not  give  rise  to  a  painful 
sensation.  In  several  instances,  nevertheless,  the  motor  nerves, 
though  insensible  at  their  origin,  show  a  certain  degree  of  sensibi- 
lity when  irritated  after  their  exit  from  the  skull,  owing  to  fibres 
of  communication  which  they  receive  from  the  purely  sensitive 
nerves.  In  this  respect  they  resemble  the  spinal  nerves,  the  motor 
and  sensitive  filaments  of  which  are  at  first  distinct  in  the  anterior 
and  posterior  roots,  but  afterward  mingle  with  each  other,  on 
leaving  the  cavity  of  the  spinal  canal. 

'  Nervous  System  of  Rana  pipiens  ;  published  by  the  Smithsonian  Institution. 
Washington,  1853. 


MOTOR  CRANIAL  NERVES.  389 

Motor  OcuLi  Communis. — This  nerve,  which  is  sometimes  known 
bj  the  more  convenient  name  of  the  oculo-molorius,  originates  from 
the  inner  edge  of  the  eras  cerebri,  passes  into  the  cavity  of  the 
orbit  by  the  sphenoidal  fissure,  and  is  distributed  to  the  levator 
palpebra3  superioris,  and  to  all  the  muscles  moving  the  eyeball, 
except  the  external  rectus  and  the  superior  oblique.  Its  irritation 
accordingly  produces  convulsive  movements  in  these  parts,  and 
its  division  has  the  effect  of  paralyzing  the  muscles  to  which  it  is 
distributed.  The  superior  eyelid  falls  down  over  the  pupil,  and 
cannot  be  raised,  owing  to  the  inaction  of  its  levator  muscle,  so 
that  the  eye  appears  constantly  half  shut.  This  condition  is  known 
by  the  name  of  "  ptosis."  The  movements  of  the  eyeball  are  also 
nearly  suspended,  and  permanent  external  strabismus  takes  place, 
owing  to  the  paralysis  of  the  internal  rectus  muscle,  while  the  ex- 
ternal rectus,  animated  by  a  different  nerve,  preserves  its  activity. 

Patheticus. — This  nerve,  which  supplies  the  superior  oblique 
muscle  of  the  eyeball,  is  similar  in  its  general  properties  to  the  pre- 
ceding. Its  section  causes  paralysis  of  the  above  muscle,  without 
any  loss  of  sensibility. 

Motor  Externus. — This  nerve,  the  sixth  pair,  according  to  the 
usual  anatomical  arrangement,  is  distributed  to  the  external  rectus 
muscle  of  the  eyeball.  Its  division  or  injury  by  disease  is  followed 
by  internal  strabismus,  owing  to  the  unopposed  action  of  the  internal 
rectus  muscle. 

Small  Root  of  5th  Pair. — It  will  be  remembered  that  the  5th 
pair  of  nerves  arises  by  two  roots,  which  run  in  close  proximity 
to  each  other,  as  far  as  the  level  of  the  Casserian  ganglion.  The 
fibres  of  the  smaller  root,  however,  do  not  mingle  at  all  with  the 
substance  of  the  ganglion,  but  pass  underneath  it,  as  a  distinct  bun- 
dle, and  emerge  afterward  from  the  skull  by  the  foramen  ovale  of 
the  sphenoid  bone,  as  a  portion  of  the  inferior  maxillary  branch  of 
the  5th  pair.  While  the  remainder  of  the  5th  pair  is  distributed 
to  the  integument  and  mucous  membranes  about  the  face,  all  the 
fibres  derived  from  this  smaller  root  are  sent  to  the  muscles  con- 
cerned in  mastication,  viz.,  the  great  temporal,  the  masseter,  the 
internal  and  external  pterygoids,  the  digastric,  and  the  mylo-hyoid. 
It  is  therefore  sometimes  known  as  the  "  masticator"  nerve.  It  is 
exclusively  the  motor  nerve  of  these  muscles ;  for  while  galvaniza- 
tion of  the  large  root  of  the  5th  pair,  according  to  Longet,  pro- 


390 


THE    CRANIAL    NERVES. 


duces  no  convulsive  movement,  but  only  a  painful  sensation,  if  the 
irritation  be  applied  to  the  small  root  alone,  the  above  muscles  are 
immediately  thrown  into  contraction,  and  the  jaws  violently  brought 
together.  Section  of  this  nerve  paralyzes  the  muscles  of  mastica- 
tion, without  affecting  the  other  muscles  of  the  face. 


Facial. — This  nerve  was  known  to  the  older  anatomists  as  the 
"  portio  dura  of  the  seventh  pair."  Tt  leaves  the  cavity  of  the 
cranium  by  the  internal  auditory  foramen,  in  company  with  the 
auditory  nerve;  and  as  the  latter  is  of  a  softer  consistency  than  the 
facial,  they  have  received  the  names  respectively  of  the  "portio 
mollis"  and  "  portio  dura"  of  the  seventh  pair.  There  is,  however, 
no  physiological  connection  between  these  two  nerves;  for  while 
the  auditory  is  spread  out  in  the  cavity  of  the  internal  ear,  the  facial 
passes  onward  through  the  petrous  portion  of  the  temporal  bone, 
emerges  at  the  stylo  mastoid  foramen,  bends  round  beneath  the 
external  ear,  and  passes  forward  through  the  substance  of  the 
parotid  gland,  forming  a  plexus,  called  the  "  pes  anserinus,"  by  the 
abundant  inosculation  of  its  branches.  Tt  then  sends  its  filaments 
forward  in  a  diverging  course,  and  is  finally  distributed  to  the 
superficial  muscles  of  the  face;  those,  namely,  which  are  concerned 
in  the  production  of  expression.  (Fig.  146.) 

The  facial,  consequently,  is  the 
motor  nerve  of  the  face.  It  has  no- 
thing to  do  with  transmitting  sen- 
sitive impressions,  since  it  has  been 
frequently  shown  that  after  section 
of  the  5th  pair,  the  facial  remaining 
entire,  the  sensibility  of  the  face  is 
completely  lost;  so  that  the  integu- 
ment may  be  cut,  pricked,  burned, 
or  lacerated,  without  any  sign  of 
pain  being  exhibited  by  the  ani- 
mal. The  facial,  therefore,  does  not 
transmit  sensation  from  these  parts ; 
and  its  division,  which  was  formerly 
resorted  to  in  cases  of  tic  doulou- 
reux, is  accordingly  altogether  in- 
capable of  relieving  neuralgic  pains. 
This  nerve  is,  however,  directly  connected  with  muscular  action. 
Mechanical  or  galvanic  irritation  of  its  fibres  produces  convulsive 


Fig.  146. 


Facial  Nerve. 


MOTOR    CRANIAL    NERVES.  391 

twitchiijgs  in  the  nostrils,  lips,  cheeks,  &c.  Section  of  the  facial 
on  one  side,  its  destruction  by  disease,  or  compression  by  a  tumor, 
induces  the  extremely  characteristic  affection  known  as  "facial 
paralysis."  The  affected  side  of  the  face  in  these  cases,  up  to  the 
median  line,  loses  altogether  its  power  of  motion,  and  at  the  same 
time  its  natural  expression.  The  corner  of  the  mouth  falls  down- 
ward, and  the  whole  lower  part  of  the  face  is  drawn  over  to  the 
opposite  side  by  the  force  of  the  antagonistic  muscles.  The  lips 
are  unable  to  retain  the  fluids  of  the  mouth,  and  the  saliva  dribbles 
away  from  between  them,  giving  to  the  face  a  remarkably  vacant 
and  helpless  appearance.  The  lower  eyelid  also  sinks  downward 
from  paralysis  of  the  orbicularis  muscle,  and  the  eye  cannot  be 
completely  closed.  It  will  be  observed  that  precisely  opposite  effects 
are  produced  upon  the  eyelids  by  paralysis  of  the  oculo-motorius 
and  of  the  facial.  In  the  former  instance,  owing  to  paralysis  of  the 
levator  palpebrse  superioris,  the  eye  is  always  partially  closed ;  in 
the  latter,  owing  to  paralysis  of  the  orbicularis,  it  is  always  par- 
tially open. 

Though  the  facial,  however,  be  essentially  a  motor  nerve,  yet  its 
principal  branches  distributed  to  the  face  have  a  certain  degree  of 
sensibility ;  that  is,  when  irritated  in  the  middle  of  their  course,  the 
animal  immediately  gives  evidence  of  a  painful  sensation.  Longet 
has  shown,  by  an  extremely  ingenious  mode  of  experiment,^  that 
this  sensibility  of  the  branches  of  the  facial  does  not  depend  on 
any  sensitive  fibres  of  its  own,  but  upon  those  which  it  derives 
from  inosculation  with  the  fifth  pair.  He  exposes,  for  example,  the 
facial  nerve  in  the  dog,  and  irritating  its  principal  branches  one 
after  the  other,  at  each  application  of  the  irritant  there  are  evident 
signs  of  pain.  He  then  divides  the  facial  nerve  at  its  point  of  exit 
from  the  stylo-mastoid  foramen,  and  finds  that,  after  this  operation, 
the  sensibility  of  its  branches  still  remains.  The  fibres,  accordingly, 
upon  which  this  sensibility  depends,  do  not  pass  out  with  the  trunk 
of  the  nerve,  but  are  derived  from  some  other  source.  The  experi- 
menter, then,  upon  another  animal,  divides  the  5th  pair  within  the 
skull,  leaving  the  facial  untouched ;  and  afterward,  on  irritating  as 
before  the  exposed  branches  of  the  latter  nerve,  he  finds  that  its 
sensibility  has  entirely  disappeared.  It  is  by  filaments,  accordingly, 
derived  from  the  5th  pair,  that  a  certain  degree  of  sensibility  is 
communicated  to  the  branches  of  the  facial. 

'  Traite  de  Physiologie,  vol.  ii.  pp.  3.54-3.57. 


392  THE  CRANIAL  NERVES. 

These  facts  account  for  the  peculiar  circumstance  that,  in  cases 
of  tic  douloureux,  the  spasmodic  pain  sometimes  follows  exactly  the 
course  of  the  facial  nerve,  viz :  from  behind  the  ear  forward  upon 
the  side  of  the  face ;  and  yet  the  section  of  this  nerve  does  not  put 
an  end  to  the  neuralgia,  but  only  causes  paralysis  of  the  facial 
muscles. 

Sublingual. — The  sublingual  nerve  originates  from  the  anterior 
and  lateral  portions  of  the  medulla  oblongata,  and  passing  out  by 
the  anterior  condyloid  foramen,  is  distributed  exclusively  to  the 
muscles  of  the  tongue.  Irritation  of  its  fibres  in  any  part  of  their 
course  produces  convulsive  twitching  in  this  organ.  Its  section 
paralyzes  completely  the  movements  of  the  tongue,  without  affecting 
directly  the  sensibility  of  its  mucous  membrane.  If  irritated  at  its 
origin,  the  sublingual  nerve,  according  to  the  experiments  of  Longet, 
is  entirely  insensible ;  but  if  the  irritation  be  applied  in  the  middle 
of  its  course,  signs  of  pain  are  immediately  manifested.  Its  sensi- 
bility, like  that  of  the  facial,  is  consequently  derived  from  its  inos- 
culating with  other  sensitive  nerves  after  its  emergence  from  the 
skull. 

Spinal  Accessory. — This  nerve  originates  by  many  filaments 
from  the  side  of  the  medulla  oblongata  below  the  level  of  the  pneu- 
mogastric,  and  also  from  the  lateral  portion  of  the  spinal  cord, 
between  the  anterior  and  posterior  roots  of  the  upper  five  or  six 
cervical  nerves.  Its  fibres  pass  upward,  enter  the  cavity  of  the  cra- 
nium by  the  foramen  magnum,  and  again  emerge  from  it  by  the 
posterior  foramen  lacerum,  in  company  with  the  jugular  vein  and 
the  glosso-pharyngeal  and  pneumogastric  nerves,  to  the  latter  of 
which  it  gives  off  an  important  branch  of  communication.  It  is 
finally  distributed  to  the  sterno-mastoid  and  trapezius  muscles. 

The  above  muscles,  however,  are  also  supplied  by  branches  from 
the  cervical  and  dorsal  nerves ;  and  consequently,  it  has  been  found 
that  division  of  the  spinal  accessory  is  not  followed  by  their  com- 
plete paralysis ;  but  only  by  a  certain  debility,  owing  to  their  having 
lost  a  part  of  their  motor  force.  The  sterno-mastoid  and  trapezius 
serve  as  accessory  muscles  of  respiration,  and  come  into  play  when 
the  respiratory  movements  are  unusually  hurried  or  laborious. 
The  spinal  accessory  was  regarded  by  Sir  Charles  Bell  as  especially 
devoted  to  this  function  in  the  above  muscles,  and  was,  therefore^ 
called,  by  him,  the  "superior  respiratory  nerve." 


SENSITIVE    CRANIAL    NERVES.  393 

The  spinal  accessory  has  been  found  by  Bernard  to  be  insensible 
at  its  origin,  like  the  anterior  roots  of  the  spinal  nerves;  but  if  irri- 
tated after  its  exit  from  the  skull,  it  gives  signs  of  sensibility.  This 
may  be  attributed  to  its  receiving  filaments  of  inosculation  from  the 
anterior  branches  of  the  first  and  second  cervical  nerves.  The  rea- 
son for  the  above  anatomical  fact,  viz.,  that  motor  nerves  are  sup- 
plied daring  their  course  with  sensitive  fibres  by  inosculation, 
becomes  evident  when  we  reflect  that  the  muscles  themselves  pos- 
sess a  certain  degree  of  sensibility,  though  less  than  that  which 
belongs  to  the  integument  and  to  some  parts  of  the  mucous  mem- 
branes. This  sensibility  of  the  muscles  is  undoubtedly  essential 
to  the  perfect  performance  of  their  function ;  and,  as  the  motor 
nerves  are  incapable  by  themselves  of  transmitting  sensitive  im- 
pressions, they  are  joined,  soon  after  their  origin,  by  other  filaments 
which  communicate  to  them  the  necessary  power. 


SENSITIVE  NERVES. 

The  three  sensitive  nerves  originating  from  the  brain  are  the 
large  root  of  the  5th  pair,  the  glosso-pharyngeal,  and  the  pneumo- 
gastric.  It  will  be  observed  that,  in  all  their  essential  properties, 
they  correspond  with  the  posterior  roots  of  the  spinal  nerves.  Like 
them  they  are  inexcitable,  but  extremely  sensitive.  Irritated  at 
their  point  of  origin,  they  give  rise  to  acutely  painful  sensations, 
but  to  no  convulsive  movements.  Secondly,  if  divided  at  the  same 
situation,  the  operation  is  followed  by  loss  of  sensibility  in  the 
parts  to  which  they  are  distributed,  without  any  disturbance  of  the 
motive  power.  Each  of  these  nerves,  furthermore,  like  the  poste- 
rior root  of  a  spinal  nerve,  is  provided  with  a  ganglion  through 
which  its  fibres  pass :  the  5th  pair,  with  the  Casserian  ganglion, 
situated  near  the  inner  extremity  of  the  petrous  portion  of  the  tem- 
poral bone ;  the  glosso-pharyngeal,  with  the  ganglion  of  Andersch, 
situated  in  the  jugular  fossa;  while  the  pneumogastric  presents, 
just  before  its  passage  through  the  jugular  foramen,  a  ganglion 
known  as  the  ganglion  of  the  pneumogastric  nerve.  Finally,  the 
sensitive  fibres  of  all  these  nerves,  beyond  the  situation  of  their 
ganglia,  are  intermingled  with  others  of  a  motor  origin.  The  large 
root  of  the  5th  pair,  wbich  is  exclusively  sensitive,  is  accompanied 
by  the  fibres  of  the  small  root,  which  are  exclusively  motor.  The 
glosso-pharyngeal  receives  motor  filaments  from  the  facial  and  spinal 


394  THE  CRANIAL  NERVES. 

accessory,  becoming  consequently  a  mixed  nerve  outside  the  cra- 
nial cavity;  while  the  pneumogastric  is  joined  by  fibres  from  the 
spinal  accessory  and  various  other  nerves  of  a  motor  character. 
These  nerves,  accordingly,  are  exclusively  sensitive  only  at  their 
point  of  origin.  Though  they  afterward  retain  the  predominating 
character  of  sensitive  nerves,  they  are  yet  found,  if  irritated  in  the 
middle  of  their  course,  to  be  intermingled  with  motor  fibres,  and 
to  have  consequently  acquired,  to  a  certain  extent,  the  character 
of  mixed  nerves. 

The  resemblance,  therefore,  between  the  cranial  and  spinal  nerves 
is  complete. 

Fifth  Pair. — This  is  one  of  the  most  important  and  remarkable 
in  its  properties  of  all  the  cranial  nerves.  It  is  the  sensitive  nerve 
of  the  face,  and  of  the  adjoining  mucous  membranes.  We  have 
already  described  the  course  and  distribution  of  the  small  root 
of  this  nerve.  The  large  root,  after  emerging  from  the  outer  and 
under  surface  of  the  pons  Varolii,  passes  forward  over  the  inner 
extremity  of  the  petrous  portion  of  the  temporal  bone.  It  there 
expands  into  a  crescentic-shaped  swelling,  containing  a  quantity  of 
gray  matter  with  which  its  fibres  are  intermingled,  and  which  is 
known  as  the  Casserian  ganglion.  The  fibres  of  the  smaller  root, 
as  already  remarked,  do  not  take  any  part  in  the  formation  of  this 
ganglion,  but  may  be  seen  passing  beneath  it  as  a  distinct  bundle, 
and  continuing  their  course  forward  to  the  foramen  ovale,  through 
which  they  emerge  from  the  skull.  From  the  anterior  and  external 
border  of  the  Casserian  ganglion,  the  sensitive  portion  of  the  nerve 
emerges  in  three  separate  branches,  viz.,  the  ophthalmic,  the  su- 
perior maxillary,  and  the  inferior  maxillary.  The  first  of  these, 
viz.,  the  ophthalmic,  is  so  called  because  it  passes  through  the 
orbit  of  the  eye.  It  enters  the  sphenoidal  fissure,  and  runs  along 
the  upper  portion  of  the  orbit,  sending  branches  to  the  ophthalmic 
ganglion  of  the  sympathetic,  to  the  lachrymal  gland,  the  conjunc- 
tiva, and  the  mucous  membrane  of  the  lachrymal  sac.  It  also  sends 
off  a  small  branch  (nasal  branch)  which  penetrates  into  the  nasal 
passages  and  supplies  the  Schneiderian  mucous  membrane.  It  then 
emerges  upon  the  face  by  the  supra-orbital  foramen,  and  is  dis- 
tributed to  the  integument  of  the  forehead  and  side  of  the  head  as 
far  back  as  the  vertex. 

The  second  branch  of  this  nerve,  or  the  superior  maxillary,  passes 
out  by  the  foramen  rotund um,  and  runs  along  the  longitudinal  canal 


SENSITIVE    NERVES. 


395 


Fis.  147. 


Distribution  of  Fifth  Nerve 
UPON  T  H  !•;  F  A  c  R  .  — n.  Casserian  ganglion. 
1.  Ophtlialmic  branch.  2.  Superior  maxil- 
lary branch.     3.  Inferior  maxillary  branch. 


in  the  floor  of  the  orbit,  giving  oft'  branches  during  its  passage 
to  the  teeth  of  the  upper  jaw  and  to  the  mucous  membrane  of 
the  antrum  maxiHare.  It  finally 
emerges  upon  the  middle  of  the 
face  by  the  infra-orbital  foramen, 
and  is  distributed  to  the  lower  eye- 
lid, the  nose,  the  cheek  and  the 
upper  lip. 

The  third,  or  inferior  maxillary 
branch  of  the  fifth  pair,  leaves  the 
cavity  of  the  cranium  by  the  fora- 
men ovale.  It  first  sends  off"  a  few 
branches  to  the  integument  of  the 
temple  and  external  ear,  then  a 
large  and  important  branch,  vi%., 
the  "gustatory"  or  "lingual" branch, 
which  is  distributed  to  the  mucous 
membrane  of  the  anterior  two-thirds 
of  the  tongue.  The  main  trunk 
then  enters  the  inferior  dental  canal, 
sends  nerves  to  the  teeth  of  the 

lower  jaw,  emerges  at  the  mental  foramen,  and  is  finally  distributed 
to  the  integument  of  the  chin,  lower  lip,  and  inferior  part  of  the  face. 

This  nerve  is  accordingly  distributed  to  the  sensitive  surfaces, 
that  is,  the  integument  and  mucous  membranes,  about  the  face. 
A  few  of  its  fibres  are  sent  also  to  the  muscles  of  the  face ;  but 
these  fibres  are  sensitive  in  their  character,  and  serve  merely 
to  impart  to  the  muscles  a  certain  degree  of  sensibility.  It  has 
been  ascertained  by  Longet  that  if  the  ganglionic  portion  of  this 
nerve  be  irritated  by  a  galvanic  current,  no  convulsive  movements 
whatever  are  produced,  even  in  those  muscles  which  are  supplied 
with  filaments  from  its  infra-orbital  and  mental  branches;  but  if 
its  smaller  or  non-ganglionic  root  be  irritated  in  the  same  way, 
contractions  instantly  follow  in  the  muscles  of  mastication. 

Irritation  of  the  5th  pair,  in  any  part  of  its  course,  as  well  as  of 
its  larger  root  behind  the  Casserian  ganglion,  produces  intense  pain. 
Its  division  is  followed  by  complete  loss  of  sensibility  in  the  in- 
tegument of  the  face,  the  lips,  the  conjunctiva,  and  mucous  mem- 
brane of  the  nares  and  mouth.  The  sense  of  taste  is  also  destroyed 
throughout  the  anterior  two-thirds  of  the  tongue,  owing  to  the 
paralysis  of  the  lingual  or  gustatory  nerve.     The  skin  of  the  face 


396  THE  CRANIAL  XERVES. 

may  then  be  pricked,  burned,  cut  or  lacerated  in  any  way,  without 
producing  pain,  and  even  apparently  without  the  knowledge  of  the 
animal  upon  whom  the  operation  is  performed. 

The  5th  pair,  beside  supplying  the  sensibility  of  the  integument 
of  the  face,  has  a  peculiar  and  important  influence  on  the  organs 
of  special  sense.  This  influence  appears  to  consist  in  some  connec- 
tion between  the  action  of  the  5th  pair  and  the  processes  of  nutrition; 
so  that  when  the  former  is  injured,  the  latter  become  immediately 
deranged.  For  the  perfect  action  of  any  one  of  the  organs  of 
special  sense,  two  conditions  are  necessary :  first,  the  sensibility  of 
the  special  nerve  belonging  to  it,  and,  secondly,  the  integrity  of  the 
component  parts  of  the  organ  itself.  Xow  as  the  nutrition  of  the 
organ  is,  to  a  certain  extent,  under  the  control  of  the  5th  pair,  any 
serious  injury  to  this  nerve  produces  a  derangement  in  the  tissues 
of  the  organ,  and  consequently  interferes  with  the  due  performance 
of  its  function. 

The  mucous  membrane  of  the  nasal  passages,  for  example,  is 
supplied  by  two  different  nerves;  first,  the  olfactory,  distributed 
throughout  its  upper  portion,  by  which  it  is  endowed  with  the 
special  sense  of  smell ;  and,  secondly,  the  nasal  branch  of  the  5th 
pair,  distributed  throughout  its  middle  and  lower  portions,  by 
which  it  is  supplied  with  ordinary  sensibility.  Although  the 
Schneiderian  mucous  membrane,  therefore,  after  destruction  of  the 
olfactory  nerve,  loses  altogether  its  power  of  distinguisMng  odors, 
properly  so  called,  such  as  the  odor  of  flowers,  of  turpentine,  of 
sulphuretted  hydrogen,  and  the  like,  it  still  remains  sensitive  to 
the  action  of  vapors  which  are  merely  irritating  in  their  character, 
such  as  those  of  ammonia  and  acetic  acid.  These  substances  act  by 
exciting  the  ordinary  sensibility  of  the  mucous  membrane,  which  is 
supplied  by  fibres  of  the  5th  pair.  They  will  also  act  in  a  similar 
manner  upon  the  integument,  or  upon  other  mucous  membranes 
endowed  with  general  sensibility  ;  while  true  odors  are  perceptible 
by  the  olfactory  organ  alone. 

The  5th  pair  accordingly  supplies  general  sensibilit}'  to  the  nasal 
passages,  and  this  property  will  remain  after  the  special  sense  of 
smell  has  been  destroyed.  If,  however,  the  5th  pair  itself  be 
divided,  not  only  is  general  sensibility  destroyed  in  the  Schneider- 
ian mucous  membrane,  but,  according  to  the  experiments  of  Longet, 
a  disturbance  begins  to  take  place  in  the  nutrition  of  its  tissue, 
by  which  it  is  gradually  rendered  unfit  for  the  performance  of 
its  special  function,  and  the  power  of  smell  is  finally  lost.     The 


SENSITIVE    CRANIAL    NERVES.  397 

mucous  membrane,  under  these  circumstances,  becomes  injected 
and  swollen,  assumes  a  fungous  consistency,  and  is  liable  to  bleed 
at  the  slightest  touch.  The  effect  of  this  alteration  is  to  blunt  or 
altogether  destroy  the  sense  of  smell.  It  is  owing  to  a  similar 
unnatural  condition  of  the  mucous  membrane  that  the  power  of 
smell  is  always  more  or  less  impaired  in  cases  of  coryza  and 
influenza.  The  olfactory  nerves  become  inactive  in  consequence  of 
the  morbid  alteration  in  their  mucous  membrane,  and  in  the  secre- 
tions which  cover  it. 

The  influence  of  this  nerve  over  the  organ  of  vision  is  still  more 
remarkable.  It  has  been  known  for  many  years  that  division  of 
the  5th  pair  within  the  cranium,  or  of  its  ophthalmic  branch,  is  fol- 
lowed by  an  inflammation  of  the  corresponding  eye  which  usually 
goes  on  to  complete  and  permanent  destruction  of  the  organ. 
Immediately  after  the  operation,  the  pupil  becomes  contracted  and 
the  conjunctiva  loses  its  sensibility.  At  the  end  of  twenty-four 
hours,  the  cornea  begins  to  become  opaline,  and,  by  the  second 
day,  the  conjunctiva  is  already  inflamed  and  begins  to  discharge  a 
purulent  secretion.  The  inflammation,  after  commencing  in  the 
conjunctiva,  increases  in  intensity  and  soon  spreads  to  the  iris, 
which  becomes  covered  with  a  layer  of  inflammatory  exudation. 
The  cornea  grows  constantly  more  opaque,  until  it  is  at  last 
altogether  impermeable  to  light,  and  vision  is  consequently  sus- 
pended. Blindness,  therefore,  does  not  result  in  these  instances 
from  any  direct  affection  of  the  optic  nerve  or  of  the  retina,  but  is 
owing  simply  to  opacity  of  the  cornea.  Sometimes  the  diseased 
action  goes  on  until  it  results  in  ulceration  of  the  cornea  and  dis- 
charge of  the  humors  of  the  eye ;  sometimes,  after  the  lapse  of 
several  days,  the  inflammatory  appearances  subside,  and  the  eye  is 
finally  restored  to  its  natural  condition. 

It  has  been  observed,  however,  that,  although  the  above  conse- 
quences always  follow  division  of  the  5th  pair  when  performed  at 
the  level  of  the  Casserian  ganglion,  or  between  it  and  the  eyeball, 
they  are  either  much  diminished  in  intensity  or  altogether  wanting 
when  the  division  is  made  at  a  point  posterior  to  the  ganglion. 
This  circumstance  has  led  to  the  belief  that  the  influence  of  the  5th 
pair  on  the  nutrition  of  the  eyeball  does  not  reside  in  its  own 
proper  fibres,  but  in  some  filaments  of  the  sympathetic  which  join 
the  5th  pair  at  the  level  of  the  Casserian  ganglion.  If  the  section 
accordingly  be  made  at  this  point,  or  in  front  of  it,  the  fibres  of  the 
sympathetic  will  be  divided  with  the  others,  and  inflammation  of 


398  THE  CRANIAL  NERVES. 

the  eye  will  result;  but  if  the  section  be  made  behind  the  ganglion, 
the  fibres  of  the  sympathetic  will  escape  division,  and  the  injurious 
effects  upon  the  eye  will  be  wanting.  Such  is  the  explanation 
usually  given  of  the  above-mentioned  facts;  but  the  question  has 
not  as  yet  been  determined  in  a  direct  manner. 

Division  of  the  5th  pair  destroys  also  the  general  sensibility  of 
the  external  auditory  meatus,  the  lining  membrane  of  which  is 
supplied  by  its  filaments.  Inflammation  of  this  membrane  and  its 
consequent  alterations,  it  is  well  known,  interfere  seriously  with 
the  sense  of  hearing.  It  is  no  uncommon  occurrence  for  an 
accumulation  of  cerumen  to  take  place  after  inflammation  of  this 
part,  so  as  to  block  up  the  canal  and  produce  partial  or  complete 
deafness.  It  has  not  been  ascertained,  however,  whether  division 
of  the  5th  pair  is  usually  followed  by  similar  changes  in  this  part. 

The  lingual  branch  of  the  5th  pair  supplies  the  anterior  ex- 
tremity and  middle  portion  of  the  tongue  both  with  general  sensi- 
bility and  with  the  power  of  taste.  The  sensibility  of.  the  tongue 
is  accordingly  provided  for  by  two  difi'erent  nerves;  in  its  anterior 
two-thirds,  by  the  lingual  branch  of  the  5th  pair ;  in  its  posterior 
third,  by  fibres  of  the  glosso-pharyngeal. 

The  facial  branches  of  the  5th  pair  are  the  ordinary  seat  of  tic 
douloureux.  This  affection  is  not  unfrequently  confined  to  either 
the  supra-orbital,  the  infra-orbital,  or  the  mental  branch ;  and  the 
pain  may  be  accurately  traced  in  the  direction  of  their  diverging 
fibres.  It  has  already  been  mentioned  that  the  painful  sensations 
sometimes  also  follow  the  course  of  the  facial,  owing  to  some  sen- 
sitive filaments  which  that  nerve  receives  from  the  5th  pair. 

Glosso-Pharyngeal. — This  nerve  originates  from  the  lateral 
portion  of  the  medulla  oblongata,  passes  outward,  and  enters  the 
posterior  foramen  lacerum  in  company  with  the  pneumogastric  and 
spinal  accessory.  While  in  the  jugular  fossa  it  presents  a  gangliform 
enlargement,  called  the  ganglion  of  Andersch,  below  the  level  of 
which  it  receives  branches  of  communication  from  the  facial  and  the 
spinal  accessory.  It  then  runs  downward  and  forward  and  is  dis- 
tributed to  the  mucous  membrane  of  the  base  of  the  tongue,  pillars 
of  the  fauces,  soft  palate,  middle  ear,  and  upper  part  of  the  pharynx. 
It  also  sends  some  branches  to  the  constrictors  of  the  pharynx  and 
the  neighboring  muscles.  Longet  has  found  this  nerve  at  its  origin 
to  be  exclusively  sensitive ;  but  below  the  level  of  its  ganglion  it 
has  been  found  by  various  observers  to  be  both  sensitive  and  motor. 


PNEUMOGASTRIC    NERVE.  399 

owing  to  the  fibres  of  communication  received  from  the  motor  nerves 
mentioned  above.  Its  final  distribution  is,  however,  as  we  have 
seen,  principally  to  sensitive  surfaces.  The  principal  office  of  this 
nerve  is  to  impart  the  sense  of  taste  to  those  parts  of  the  tongue  to 
which  it  is  distributed.  It  also  presides  over  the  general  sensibility 
of  this  part  of  the  tongue,  as  well  as  of  the  fauces  and  pharynx. 

There  are  certain  reflex  actions,  furthermore,  which  take  place 
through  the  medium  of  the  glosso-pharyngeal  nerve.  After  the 
food  has  been  thoroughly  masticated,  it  is  carried,  by  the  move- 
ments of  the  tongue  and  sides  of  the  mouth,  through  the  fauces, 
and  brought  in  contact  with  the  mucous  membrane  of  the  pharynx. 
This  produces  an  impression  which,  conveyed  to  the  medulla 
oblongata  by  the  filaments  of  the  glosso-pharyngeal,  excites  the 
muscles  of  the  fauces  and  pharynx  by  reflex  action.  The  food  is 
consequently  grasped  by  these  muscles,  without  the  concurrence  of 
the  will,  and  the  process  of  deglutition  is  commenced.  This  action 
is  not  only  involuntary,  but  it  will  frequently  take  place  even  in 
opposition  to  the  will.  The  food,  once  past  the  isthmus  of  the  fauces, 
is  beyond  the  control  of  volition,  and  cannot  be  returned  except  by 
convulsive  action,  equally  involuntary  in  its  character. 

Natural  stimulants,  therefore,  applied  to  the  mucous  membrane 
of  the  pharynx,  excite  deglutition  ;  unnatural  stimulants,  applied  to 
the  same  part,  excite  vomiting.  If  the  finger  be  introduced  into 
the  fauces  and  pharynx,  or  if  the  mucous  membrane  of  these  parts 
be  irritated  by  prolonged  tickling  with  the  end  of  a  feather,  the 
sensation  of  nausea,  conveyed  through  the  glosso-pharyngeal  nerve, 
is  sometimes  so  great  as  to  produce  immediate  and  copious  vomit- 
ing. This  method  may  often  be  successfully  employed  in  cases  of 
poisoning,  when  it  is  desirable  to  excite  vomiting  rapidly,  and  when 
emetic  medicines  are  not  at  hand. 

Pneumogastric. — Owing  to  the  numerous  connections  of  the 
pneumogastric  with  other  nerves,  its  varied  and  extensive  distribu- 
tion, and  the  important  character  of  its  functions,  this  is  properly 
regarded  as  one  of  the  most  remarkable  nerves  in  the  whole  body. 
Owing  to  the  wandering  course  of  its  fibres,  which  are  distributed 
to  no  less  than  four  different  vital  organs,  viz.,  the  heart,  lungs, 
stomach,  and  liver,  as  well  as  to  several  other  parts  of  secondary 
importance,  it  has  been  often  known  by  the  name  of  the  jmr  vagum. 
The  pneumogastric  arises,  by  a  number  of  separate  filaments,  from 
the  lateral  portion  of  the  medulla  oblongata,  in  the  groove  between 


400 


THE    CRANIAL    NERVES. 


the  olivary  and  restiform  bodies.  These  filaments  unite  into  a 
single  trunk,  which  emerges  from  the  cranium  by  the  jugular  fora- 
men, where  it  is  provided  with  a  longitudinal  ganglionic  swelling, 
the  "ganglion  of  the  pneuraogastric  nerve."  Immediately  below 
the  level  of  this  ganglion  the  nerve  receives  an  important  branch 

of  communication  from  the  spinal  acces- 
sory, and  afterward  from  the  facial,  the 
sublingual,  and  the  anterior  branches  of 
the  first  and  second  cervicals. 

At  its  origin,  the  pneumogastric  is  ex- 
clusively a  sensitive  nerve.  Irritated 
above  the  situation  of  its  ganglion,  it  has 
been  found  to  convey  painful  sensations 
alone ;  but  if  the  irritation  be  applied  at 
a  lower  level,  it  causes  at  the  same  time 
muscular  contractions,  owing  to  the  fila- 
ments which  it  has  received  from  the 
above  mentioned  motor  nerves.  It  be- 
comes, consequently,  after  emerging  from 
the  cranial  cavity,  a  mixed  nerve;  and 
has  accordingly,  in  nearly  all  its  branches, 
a  double  distribution,  viz.,  to  the  mucous 
membranes  and  the  muscular  coat  of  the 
organs  to  which  it  belongs. 

In  passing  down  the  neck  this  nerve 
sends  branches  to  the  mucous  membranes 
and  muscular  coat  of  the  pharynx,  oeso- 
phagus, and  respiratory  passages.  Among 
the  most  important  of  these  are  the  two 
laryngeal  nerves,  viz.,  the  superior  and 
inferior.  The  superior  laryngeal  nerve, 
which  is  given  off"  from  the  trunk  of  the 
pneumogastric  just  after  it  has  emerged 
from  the  cavity  of  the  skull,  passes  down- 
ward and  forward,  penetrates  the  larynx 
by  an  opening  in  the  side  of  the  thyro- 
hyoid membrane,  and  is  distributed  to  the 
raucous  membrane  of  the  larynx  and  glottis,  and  also  to  a  single 
laryngeal  muscle,  viz.,  the  crico-thyroid.  This  branch  is  therefore 
partly  muscular,  but  mostly  sensitive  in  its  distribution.  The  infe- 
rior laryngeal  branch  is  given  off  just  after  the  pneumogastric  has 


Diagram  of  Pneumogastric 
N  E  B  V  E,  with  its  principal  branches. 
— ^1.  Pharyngeal  branch.  2.  Supe- 
rior laryngeal.  3.  Inferior  laryn- 
geal. 4.  Pulmonary  branches.  5. 
Stomach.     6.  Liver. 


PNEUMOGASTRIC.  401 

entered  the  cavity  of  the  chest.  It  curves  round  the  subclavian 
artery  on  the  right  side  and  the  arch  of  the  aorta  on  the  left,  and 
ascends  in  the  groove  between  the  trachea  and  oesophagus,  to  the 
larynx.  It  then  enters  the  larynx  between  the  cricoid  cartilage  and 
the  posterior  edge  of  the  thyroid,  and  is  distributed  to  all  the  mus- 
cles of  the  larynx,  with  the  exception  of  the  crico-thyroid.  This 
branch  is,  therefore,  exclusively  muscular  in  its  distribution. 

The  trunk  of  the  pneumogastric,  after  supplying  the  above 
branches,  as  well  as  sending  numerous  filaments  in  the  neck  to  the 
trachea  and  oesophagus,  gives  off  in  the  chest  its  pulmonary 
branches,  which  follow  the  bronchial  tubes  in  the  lungs  to  their 
minutest  ramifications.  It  then  passes  into  the  abdomen  and  sup- 
plies the  muscular  and  mucous  layers  of  the  stomach,  ramifying 
over  both  the  anterior  and  posterior  surfaces  of  the  organ;  after 
which  its  fibres  spread  out  and  are  distributed  to  the  liver,  spleen, 
pancreas,  and  gall-bladder. 

The  functions  of  the  pneumogastric  will  now  be  successively 
studied  in  the  various  organs  to  which  it  is  distributed. 

Pharynx   and   (Esophagus.  —  The   reflex   action   of  deglutition, 
which  has  already  been  described  as  commencing  in  the  upper 
part  of  the  pharynx,  by  means  of  the  glosso-pharyngeal,  is  con- 
tinued in  the  lower  portion  of  the  pharynx  and  throughout  the 
oesophagus  by  the  pneumogastric.     As  the  food  is  compressed  by 
the  superior  constrictor  muscle  of  the  pharynx  and  forced  down- 
ward, it  excites  the  mucous  membrane  with  which  it  is  brought  in 
contact  and  gives  rise  to  another  contraction  of  the  middle  constric- 
tor.    The  lower  constrictor  is  then  brought  into  action  in  its  turn 
in  a  similar  manner;  and  a  wave-like  or  peristaltic  contraction  is 
thence  propagated  throughout  the  entire  length  of  the  oesophagus, 
by  which  the  food  is  carried  rapidly  from  above  downward,  and 
conducted  at  last  to  the  stomach.     Each  successive  portion  of  the 
raucous  membrane,  in  this  instance,  receives  in  turn  the  stimulus 
of  the  food,  and  excites  instantly  its  own  muscles  to  contraction  ; 
so  that  the  food  passes  rapidly  from  one  end  of  the  oesophagus  to 
the  other  by  an  action  which  is  wholly  reflex  in  character  and 
entirely  withdrawn  from  the  control  of  the  will.     Section  of  the 
pneumogastric,  or  of  its  pharyngeal   and   oesophageal   branches, 
destroys  therefore  at  the  same  time  the  sensibility  and  the  motive 
power  of  these  parts.     The  food  is  no  longer  conveyed  readily  to 
the  stomach,  but  accumulates  in  the  paralyzed  oesophagus,  into 
which  it  is  forced  by  the  voluntary  movements  of  the  mouth  and 
26 


402  THE  CRANIAL  NERVES, 

fauces,  and  by  the  coDtinued  action  of  the  upper  part  of  the 
pharynx. 

It  must  be  remembered  that  the  general  sensibility  of  the  oeso- 
phagus is  very  slight,  as  compared  with  that  of  the  integument,  or 
even  of  the  mucous  membranes  near  the  exterior.  It  is  a  general 
rule,  in  fact,  that  the  sensibility  of  the  mucous  membranes  is  most 
acute  at  the  external  orifices  of  their  canals ;  as,  for  example,  at  the 
lips,  anterior  nares,  anus,  orifice  of  the  urethra,  &c.  It  diminishes 
constantly  from  without  inward,  and  disappears  altogether  at  a 
certain  distance  from  the  surface.  The  sensibility  of  the  pharynx 
is  less  acute  than  that  of  the  mouth,  but  is  still  sufficient  to  enable 
us  to  perceive  the  contact  of  ordinary  substances ;  while  in  the 
oesophagus  we  are  not  usually  sensible  of  the  impression  of  the 
food  as  it  passes  from  above  downward.  The  reflex  action  takes 
place  here  without  any  assistance  from  the  consciousness ;  and  it 
is  only  when  substances  of  an  unusually  pungent  or  irritating 
nature  are  mingled  with  the  food,  that  its  passage  through  the 
oesophagus  produces  a  distinct  sensation. 

Larynx. — We  have  already  described  the  course  and  distribution 
of  the  two  laryngeal  branches  of  the  pneumogastric.  The  superior 
laryngeal  nerve  is  principally  the  sensitive  nerve  of  the  larynx. 
Its  division  destroys  sensibility  in  the  mucous  membrane  of  this 
organ,  but  paralyzes  only  one  of  its  muscles,  viz  :  the  crico-thyroid. 
Galvanization  of  this  nerve  has  also  been  found  to  induce  con- 
tractions in  the  crico-thyroid,  but  in  none  of  the  other  muscles 
belonging  to  the  larynx.  The  inferior  laryngeal,  on  the  other 
hand,  is  a  motor  nerve.  Its  division  paralyzes  all  the  muscles  of 
the  larynx  except  the  crico-thyroid,  and  irritation  of  its  divided 
extremity  produces  contraction  in  the  same  muscles.  The  muscles 
and  mucous  membrane  of  the  larynx  are  therefore  supplied  by  two 
different  branches  of  the  same  trunk,  viz.,  the  superior  laryngeal 
nerve  for  the  mucous  membrane,  and  the  inferior  laryngeal  nerve 
for  the  muscles. 

The  larynx,  in  man  and  in  all  the  higher  animals,  performs  a 
double  function ;  one  part  of  which  is  connected  with  the  voice,  the 
other  with  respiration. 

The  formation  of  the  voice  in  the  larynx  takes  place  as  follows. 
If  the  glottis  be  exposed  in  the  living  animal,  as  already  described 
in  a  previous  chapter  (Section  I.,  Chap.  XII.),  it  will  be  seen  that 
so  long  as  the  vocal  chords  preserve  their  usual  relaxed  condition 
during  expiration,  no  sound  is  heard,  except  the  ordinary  faint 


PNEUMOGASTRIC.  403 

whisper  of  the  air  passing  gently  through  the  cavity  of  the  larynx. 
When  a  vocal  sound,  however,  is  to  be  produced,  the  chorus  are 
suddenly  made  tense  and  applied  closely  to  each  other,  so  as  to 
diminish  very  considerabl}"-  the  size  of  the  orifice;  and  the  air, 
driven  by  an  unusually  forcible  expiration  through  the  narrow 
opening  of  the  glottis,  in  passing  between  the  vibrating  vocal 
chords,  is  itself  thrown  into  vibrations  which  produce  the  sound 
required.  The  tone,  pitch,  and  intensity  of  this  sound,  vary  with 
the  conformation  o  the  larynx,  the  degree  of  tension  and  approxi- 
mation of  the  vocal  chords,  and  the  force  of  the  expiratory  effort. 
The  narrower  the  opening  of  the  glottis,  and  the  greater  the 
tension  of  the  chords,  under  ordinary  circumstances,  the  more 
acute  the  sound;  while  a  wider  opening  and  a  less  degree  of 
tension  produce  a  graver  note.  The  quality  of  the  sound  is  also 
modified  by  the  length  of  the  column  of  air  included  between  the 
glottis  and  the  month,  the  tense  or  relaxed  condition  of  the  walls 
of  the  pharynx  and  fauces,  and  the  state  of  dryness  or  moisture 
of  the  mucous  membrane  lining  the  aerial  passages. 

Articulation,  on  the  other  hand,  or  the  division  of  the  vocal 
sound  into  vowels  and  consonants,  is  accomplished  entirely  by  the 
lips,  tongue,  teeth,  and  fauces.  These  organs,  however,  are  under 
the  control  of  other  nerves,  and  the  mechanism  of  their  action  need 
not  occupy  us  here. 

Since  the  production  of  a  vocal  sound,  therefore,  depends  upon 
the  tension  and  position  of  the  vocal  chords,  as  determined  by  the 
action  of  the  laryngeal  muscles,  it  is  not  surprising  that  division  of 
the  inferior  laryngeal  nerves,  by  paraljT'zing  these  muscles,  should 
produce  a  loss  of  voice.  It  has  been  sometimes  found  that  in 
very  young  animals  the  crico-thyroid  muscles,  which  are  the  only 
ones  not  affected  by  division  of  the  inferior  laryngeal  nerves, 
are  still  sufficient  to  give  some  degree  of  tension  to  the  vocal 
chords,  and  to  produce  in  this  way  an  imperfect  sound;  but 
usually  the  voice  is  entirely  lost  after  such  an  operation. 

It  is  a  very  remarkable  fact,  however,  in  this  connection,  that  all 
the  motor  filaments  of  the  pneumogastric,  which  are  concerned  in 
the  formation  of  the  voice,  are  derived  from  a  single  source.  It 
will  be  remembered  that  the  pneumogastric,  itself  originally  a 
sensitive  nerve,  receives  motor  filaments,  on  leaving  the  cranial 
cavity,  from  no  less  than  five  different  nerves.  Of  these  filaments, 
however,  those  coming  from  the  spinal  accessory  are  the  only  ones 
necessary  to  the  production  of  vocal  sounds.     For  it  has  been 


404  THE    CRANIAL    NEEVES. 

found  by  Bischofif  and  by  Bernard^  that  if  all  the  roots  of  the 
spinal  accessory  be  divided  at  their  origin,  or  if  the  nerve  itself 
be  torn  away  at  its  exit  from  the  skull,  all  the  other  cranial  nerves 
remaining  untouched,  the  voice  is  lost  as  completely  as  if  the 
inferior  laryngeal  itself  had  been  destroyed.  All  the  motor  fibres 
of  the  pneumogastric,  therefore,  which  act  in  the  formation  of  the 
voice  are  derived,  by  inosculation,  from  the  spinal  accessory  nerve. 
In  respiration^  again,  the  larynx  performs  another  and  still  more 
important  function.  In  the  first  place,  it  stands  as  a  sort  of  guard, 
or  sentinel,  at  the  entrance  of  the  respiratory  passages,  to  prevent 
the  intrusion  of  foreign  substances.  If  a  crumb  of  bread  accidentally 
fall  within  the  aryteno-epiglottidean  folds,  or  upon  the  edges  of  the 
vocal  chords,  or  upon  the  posterior  surface  of  the  epiglottis,  the 
sensibility  of  these  parts  immediately  excites  a  violent  expulsive 
cough,  by  which  the  foreign  body  is  dislodged.  The  impression, 
received  and  conveyed  inward  by  the  sensitive  fibres  of  the  supe- 
rior laryngeal  nerve,  is  reflected  back  upon  the  expiratory  muscles 
of  the  chest  and  abdomen,  by  whicb  the  instinctive  movements  of 
coughing  are  accomplished.  Touching  the  above  parts  with  the 
point  of  a  needle,  or  pinching  them  with  the  blades  of  a  forceps, 
will  produce  the  same  effect.  This  reaction  is  essentially  dependent 
on  the  sensibility  of  the  laryngeal  mucous  membrane ;  and  it  can 
no  longer  be  produced  after  section  of  the  pneumogastric  nerve,  or 
of  its  superior  laryngeal  branch. 

In  the  second  place,  the  respiratory  movements  of  the  glottis^  already 
described  in  a  previous  chapter,  are  of  the  greatest  importance  to 
the  preservation  of  life.  We  have  seen  tbat  at  the  moment  of 
inspiration  the  vocal  chords  are  separated  from  each  other,  and  the 
glottis  opened,  by  the  action  of  the  posterior  crico  arytenoid  muscles; 
and  tbat  in  expiration  the  muscles  and  the  vocal  chords  are  botb 
relaxed,  and  the  air  allowed  to  pass  out  readily  througb  the  glottis. 
The  opening  of  the  glottis  in  inspiration  therefore  is  an  active 
movement,  while  its  partial  closure  or  collapse  in  expiration  is  a 
passive  one.  Furthermore,  the  opening  of  the  glottis  in  inspiration 
is  necessary  in  order  to  afford  a  sufficiently  wide  passage  for  the 
air,  in  its  way  to  the  trachea,  bronchi,  and  pulmonary  vesicles. 

Now  we  have  found,  as  Budge  and  Longet  had  previously  no- 
ticed, that  if  the  inferior  laryngeal  nerve  on  the  right  side  be 
divided  while  the  glottis  is  exposed  as  above,  the  respiratory  move- 

'  Reclierclies  Experimentales  sur  les  fonctions  du  nerf  spinal.     Paris,  1851. 


PNEUMOGASTEIC.  405 

ments  of  the  right  vocal  chord  instantly  cease,  owing  to  the  para- 
lysis of  the  posterior  crico-arytenoid  muscle  on  that  side.  If  the 
inferior  laryngeal  nerve  on  the  left  side  be  also  divided,  the  para- 
lysis of  the  glottis  is  then  complete,  and  its  respiratory  movements 
cease  altogether.  A  serious  difficulty  in  respiration  is  the  imme- 
diate consequence  of  this  operation.  For  the  vocal  chords,  being 
no  longer  stretched  and  separated  from  each  other  at  the  moment  of 
inspiration,  but  remaining  lax  and  flexible,  act  as  a  double  valve, 
and  are  pressed  inward  by  the  column  of  inspired  air ;  thus  par- 
tially blocking  up  the  passage  and  impeding  the  access  of  air  to 
the  lungs.  If  the  pneumogastrics  be  divided  in  the  middle  of  the 
neck,  the  larynx  is  of  course  paralyzed  precisely  as  after  section 
of  the  inferior  laryngeal  nerves,  since  these  nerves  are  given  ofi" 
only  after  the  main  trunks  have  entered  the  cavity  of  the  chest ; 
and  the  immediate  effect  of  either  of  these  operations  is  to  produce 
a  difficulty  of  inspiration,  accompanied  by  a  peculiar  wheezing  or 
sucking  noise,  evidently  produced  in  the  larynx  and  dependent  on 
the  falling  together  of  the  vocal  chords.  In  very  young  animals, 
as  for  example  in  pups  of  a  few  days  old,  in  whom  the  glottis  is 
smaller  and  the  larynx  less  rigid  than  in  adult  dogs,  this  difficulty 
is  much  more  strongly  marked.  Legallois'  has  even  seen  a  pup  of 
two  days  old  almost  instantly  suffocated  after  section  of  the  two 
inferior  laryngeal  nerves.  We  have  found  that  in  pups  of  two 
weeks  old,  division  of  the  inferior  laryngeals  is  followed  by  death 
at  the  end  of  from  thirty  to  forty  hours,  evidently  from  impeded 
respiration. 

The  importance,  therefore,  of  these  movements  of  the  glottis  in 
respiration  becomes  very  evident.  They  are,  in  fact,  part  and 
parcel  of  the  general  respiratory  movements,  and  are  necessary  to 
a  due  performance  of  the  function.  It  has  been  found,  moreover, 
that  the  motor  filaments  concerned  in  this  action  are  not  derived, 
like  those  of  the  voice,  from  a  single  source.  While  the  vocal 
movements  of  the  larynx  are  arrested,  as  mentioned  above,  by 
division  of  the  spinal  accessory  alone,  those  of  respiration  still  go 
on ;  and  in  order  to  put  a  stop  to  the  latter,  either  the  pneumo- 
gastrics themselves  must  be  divided,  or  all  five  of  the  motor  nerves 
from  which  their  accessory  filaments  are  derived.  This  fact  has 
been  noticed  by  Longet  as  showing  that  nature  multiplies  the  safe- 
guards of  a  function  in  proportion  to  its  importance ;  for  while  the 

'  lu  Longet's  Traite  de  Physiologie.  vol.  ii.  p.  324. 


406  THE    CEANIAL    NERVES. 

spinal  accessory,  or  any  other  one  of  the  above  mentioned  nerves, 
might  be  affected  by  local  accident  or  disease,  it  would  be  very 
improbable  that  any  single  injury  should  paralyze  simultaneously 
the  spinal  acessory,  the  facial,  the  sublingual,  and  the  first  and 
second  cervicals.  The  respiratory  movements  of  the  larynx  are 
consequently  much  more  thoroughly  protected  than  those  which 
are  merely  concerned  in  the  formation  of  the  voice. 

Lungs. — The  influence  of  the  pneumogastric  upon  the  function 
of  the  lungs  is  exceedingly  important.  The  nerve  acts  here,  as  in 
most  other  organs  to  which  it  is  distributed,  in  a  double  or  mixed 
capacity ;  but  it  is  principally  as  the  sensitive  nerve  of  the  lungs 
that  it  has  thus  far  received  attention.  It  is  this  nerve  which 
conveys  from  the  lungs  to  the  medulla  oblongata  that  peculiar 
impression,  termed  hesoin  de  respirer,  which  excites  by  reflex  action 
the  diaphragm  and  intercostal  muscles,  and  keeps  up  the  play  of 
the  respiratory  movements.  As  we  have  already  shown,  this  action 
is  an  involuntary  one,  and  will  even  take  place  when  consciousness 
is  entirely  suspended.  It  may  indeed  be  arrested  for  a  time  by  an 
effort  of  the  will;  but  the  impression  conveyed  to  the  medulla  soon 
becomes  so  strong,  and  the  stimulus  to  inspiration  so  urgent,  that 
it  can  no  longer  be  resisted,  and  the  muscles  contract  in  spite  of  our 
attempts  to  restrain  them. 

A  very  remarkable  effect  is  accordingly  produced  on  respiration 
by  simultaneous  division  of  both  pneumogastric  nerves.  This 
experiment  is  best  performed  on  adult  dogs,  which  may  be  ether- 
ized, and  the  nerves  exposed  while  the  animal  is  in  a  condition  of 
insensibility,  avoiding,  in  this  way,  the  disturbance  of  respiration, 
which  would  follow  if  the  dissection  were  performed  while  the  ani- 
mal was  conscious  and  sensible  to  pain.  After  the  effects  of  the 
etherization  have  entirely  passed  off,  and  respiration  and  circulation 
have  both  returned  to  a  quiescent  condition,  the  two  nerves,  which 
have  been  previously  exposed  and  secured  by  a  loose  ligature,  may 
be  instantaneously  divided,  and  the  effects  of  the  operation  readily 
appreciated. 

Immediately  after  the  division  of  the  nerves,  when  performed  in 
the  above  manner,  the  respiration  is  hurried  and  difStcult,  owing  to 
the  sudden  paralysis  of  the  larynx  and  partial  closure  of  the  glottis 
by  the  vocal  chords,  as  already  described.  This  condition,  how- 
ever, is  of  short  continuance.  In  a  few  moments,  the  difficulty  of 
breathing  and  the  general  agitation  subside,  the  animal  becomes 
perfectly  quiet,  and  the  only  remaining  visible  effect  of  the  opera- 


PNEUMOGASTRIC.  407 

tion  is  a  dimimshed  fnquency  in  the  movements  of  respiration.  This 
diminution  is  frequently  strongly  marked  from  the  first,  the  number 
of  respirations  falling  at  once  to  ten  or  fifteen  per  minute,  and  be- 
coming, in  an  hour  or  two,  still  farther  reduced.  The  respirations 
are  performed  easily  and  quietly ;  and  the  animal,  if  left  undisturbed, 
remains  usually  crouched  in  a  corner,  without  giving  any  special 
signs  of  discomfort.  If  he  be  aroused  and  compelled  to  move 
about,  the  frequency  of  the  respiration  is  temporarily  augmented  ; 
but  as  soon  as  he  is  again  quiet,  it  returns  to  its  former  standard. 
By  the  second  or  third  day,  the  number  of  respirations  is  often 
reduced  to  five,  four,  or  even  three  per  minute;  when  this  is  the 
case,  the  animal  usually  appears  very  sluggish,  and  is  roused  with 
difficulty  from  his  inactive  condition.  At  this  time,  the  respiration 
is  not  only  diminished  in  frequency,  but  is  also  performed  in  a 
peculiar  manner.  The  movement  of  inspiration  is  slow,  easy,  and 
silent,  occupying  several  seconds  in  its  accomplishment;  expiration, 
on  the  contrary,  is  sudden  and  audible,  and  is  accompanied  by  a  well 
marked  expulsive  effort,  which  has  the  appearance  of  being,  to  a 
certain  extent,  voluntary  in  character.  The  intercostal  spaces  also 
sink  inward  during  the  lifting  of  the  ribs;  and  the  whole  movement 
of  respiration  has  an  appearance  of  insufficiency,  as  if  the  lungs 
were  not  thoroughly  filled  with  air.  This  insufficiency  of  respira- 
tion is  undoubtedly  owing  to  a  peculiar  alteration  in  the  pulmonary 
texture,  which  has  by  this  time  already  commenced. 

Death  takes  place  at  a  period  varying  from  one  to  six  days  after 
the  operation,  according  to  the  age  and  strength  of  the  animal. 
The  only  symptoms  accompanying  it  are  a  steady  failure  of  the 
respiration,  with  increased  sluggishness  and  indisposition  to  be 
aroused.  There  are  no  convulsions,  nor  any  evidences  of  pain. 
After  death,  the  lungs  are  found  in  a  peculiar  state  of  solidification, 
which  is  almost  exclusively  a  consequence  of  this  operation,  and 
which  is  entirely  different  from  ordinary  inflammatory  hepatization. 
They  are  not  swollen,  but  rather  smaller  than  natural.  They  are 
of  a  dark  purple  color,  leathery  and  resisting  to  the  feel,  destitute 
of  crepitation,  and  infiltrated  with  blood.  Pieces  of  the  lung  cut 
out  sink  in  water.  The  pleural  surfaces,  at  the  same  time,  are  bright 
and  polished,  and  their  cavity  contains  no  effusion  or  exudation. 
The  lungs,  in  a  word,  are  simply  engorged  with  blood  and  empty 
of  air;  their  tissue  having  undergone  no  other  alteration. 

These  changes  are  not  generally  uniform  over  both  lungs.     The 
organs  are  usually  mottled  on  their  exterior;  the  variations  in  color 


408  THE    CRANIAL    NERVES. 

corresponding  with  the  different  degrees  of  alteration  exhibited  by 
different  parts. 

The  explanation  usually  adopted  of  the  above  consequences  fol- 
lowing division  of  the  pneumogastrics  is  as  follows:  The  nerves 
being  divided,  the  impression  which  originates  in  the  lungs  from 
the  accumulation  of  carbonic  acid,  and  which  is  destined  to  excite 
the  respiratory  movements  by  reflex  action,  can  no  longer  be  trans- 
mitted to  the  medulla  oblongata.  The  natural  stimulus  to  respira- 
tion being  wanting,  it  is,  accordingly,  less  perfectly  performed.  The 
respiratory  movements  diminish  in  frequency,  and,  growing  con- 
tinually slower  and  slower,  finally  cease  altogether,  and  death  is  the 
result. 

The  above  explanation,  however,  is  not  altogether  sufficient.  It 
accounts  very  well  for  the  diminished  frequency  of  the  respiration, 
but  not  for  its  partial  continuance.  For  if  the  pneumogastric  nerves 
be  really  the  channel  through  which  the  stimulus  to  respiration  is 
conveyed  to  the  medulla,  the  difficulty  is  not  to  understand  why 
respiration  should  be  retarded  after  division  of  these  nerves,  but 
why  it  should  continue  at  all.  In  point  of  fact,  the  respiratory 
movements,  though  diminished  in  frequency,  continue  often  for 
some  days  after  this  operation.  This  cannot  be  owing  to  force  of 
habit,  or  to  any  remains  of  nervous  influence,  as  has  been  some- 
times suggested,  since,  when  the  medulla  itself  is  destroyed,  respira- 
tion, as  we  know,  stops  instantaneously,  and  no  attempt  at  move- 
ment is  made  after  the  action  of  the  nervous  centre  is  suspended. 

It  is  evident,  therefore,  that  the  pneumogastric  nerve,  though  the 
chief  agent  by  which  the  respiratory  stimulus  is  conveyed  to  the 
medulla,  is  not  the  only  one.  The  lungs  are  undoubtedly  the 
organs  which  are  most  sensitive  to  an  accumulation  of  carbonic 
acid,  and  an  imperfect  arterialization  of  the  blood ;  and  the  sensa- 
tion which  results  from  such  an  accumulation  is  accordingly  first 
felt  in  them.  There  is  reason  to  believe,  however,  that  all  the  vas- 
cular organs  are  more  or  less  capable  of  originating  this  impression, 
and  that  all  the  sensitive  nerves  are  capable,  to  some  extent,  of  trans- 
mitting it.  Although  the  first  disagreeable  sensation  on  holding 
the  breath  makes  itself  felt  in  the  lungs,  yet,  if  we  persist  in  sus- 
pending the  respiration,  we  soon  become  conscious  that  the  feeling 
of  discomfort  spreads  to  other  parts ;  and  at  last,  when  the  accu- 
mulation of  carbonic  acid  and  the  impurity  of  the  blood  have 
become  excessive,  all  parts  of  the  body  suffer  alike,  and  are  per- 
vaded by  a  general  feeling  of  derangement  and  distress.    It  is  easy. 


PNEUMOGASTRIC.  409 

therefore,  to  understand  why  respiration  should  be  retarded,  after 
section  of  the  pneumogastrics,  since  the  chief  source  of  the  stimulus 
to  respiration  is  cut  ofl";  but  the  movements  still  go  on,  though  more 
slowly  than  before,  because  the  other  sensitive  nerves,  which  con- 
tinue to  act,  are  also  capable,  in  an  imperfect  manner,  of  conveying 
the  same  impression. 

The  immediate  cause  of  death,  after  this  operation,  must  no 
doubt  be  principally  sought  for  in  the  altered  condition  of  the 
lungs.  These  organs  are  evidently  very  imperfectly  filled  with  air, 
for  some  time  previous  to  death  ;  and  their  condition,  as  shown  in 
post-mortem  examination,  is  evidently  incompatible  with  a  due 
performance  of  the  respiratory  function.  It  is  not  at  all  certain, 
however,  that  these  alterations  in  the  pulmonary  tissue  are  directly 
dependent  on  division  of  the  pneumogastric  nerves.  It  must  be 
recollected  that  when  the  section  of  the  pneumogastrics  is  performed 
in  the  middle  of  the  neck,  the  filaments  of  the  inferior  laryngeal 
nerves  are  also  divided,  and  the  narrowing  of  the  glottis,  produced 
by  their  paralysis,  must  necessarily  interfere  with  the  free  admission 
of  air  into  the  chest.  This  diflSculty,  either  alone  or  combined  with 
the  diminished  frequency  of  respiration,  must  have  a  very  con- 
siderable effect  in  impeding  the  pulmonary  circulation,  and  bringing 
the  lungs  into  such  a  condition  as  unfits  them  for  maintaining  life. 

In  order  to  ascertain  the  comparative  influence  upon  the  lungs 
of  division  of  the  inferior  laryngeals  and  that  of  the  other  filaments 
of  the  pneumogastrics,  we  have  resorted  to  the  following  experi- 
ment. 

Two  pups  were  taken,  belonging  to  the  same  litter  and  of  the 
same  size  and  vigor,  about  two  weeks  old.  In  one  of  them  (No.  1) 
the  pneumogastrics  were  divided  in  the  middle  of  the  neck;  and 
in  the  other  (No.  2)  a  section  was  made  at  the  same  time  of  the 
inferior  laryngeals,  the  trunk  of  the  pneumogastrics  being  left  un- 
touched. For  the  first  few  seconds  after  the  operation,  there  was 
but  little  difi'erence  in  the  condition  of  the  two  animals.  There  was 
the  same  obstruction  to  the  breath  (owing  to  closure  of  the  glottis), 
the  same  gasping  and  sucking  inspiration,  and  the  same  frothing  at 
the  mouth.  Yery  soon,  however,  in  pup  No.  1,  the  respiratory  move- 
ments became  quiescent,  and  at  the  same  time  much  reduced  in 
frequency,  falling  to  ten,  eight,  and  five  respirations  per  minute,  as 
usual  after  section  of  the  pneumogastrics ;  while  in  No.  2  the  re- 
spiration continued  frequent  as  well  as  laborious,  and  the  general 
signs  of  agitation  and  discomfort  were  kept  up  for  one  or  two  hours. 


410  THE  CKANIAL  NERVES. 

The  animal,  however,  after  that  time  became  exhausted,  cool,  and 
partially  insensible,  like  the  other.  They  both  died,  between  thirty 
and  forty  hours  after  the  operation.  On  post-mortem  inspection  it 
was  found  that  the  peculiar  congestion  and  solidification  of  the 
lungs,  considered  as  characteristic  of  division  of  the  pneumogastrics, 
existed  to  a  similar  extent  in  each  instance ;  and  the  only  appre- 
ciable difference  between  the  two  bodies  was  that  in  No.  1  the  blood 
was  coagulated,  and  the  abdominal  organs  natural,  while  in  No.  2 
the  blood  was  fluid  and  the  abdominal  organs  congested.  We  are 
led,  accordingly,  to  the  following  conclusions  with  regard  to  the 
effect  produced  by  division  of  this  nerve. 

1.  After  section  of  the  pneumogastrics,  death  takes  place  by  a  pecu- 
liar congestion  of  the  lungs. 

2.  This  congestion  is  not  directly  produced  by  division  of  the 
nerves,  but  is  caused  by  the  imperfect  admission  of  air  into  the 
chest. 

In  adult  dogs,  the  closure  of  the  glottis  from  paralysis  of  the 
laryngeal  muscles  is  less  complete  than  in  pups ;  but  it  is  still 
sufficient  to  exert  a  very  decided  influence  on  respiration,  and  to 
take  an  active  part  in  the  production  of  the  subsequent  morbid 
phenomena. 

We  therefore  regard  the  death  which  takes  place  after  division 
of  both  pneuraogastric  nerves,  as  produced  in  the  following  man- 
ner : — 

The  glottis  is  first  narrowed  by  paralysis  of  the  laryngeal  mus- 
cles, and  an  imperfect  supply  of  air  is  consequently  admitted,  by 
each  inspiration,  into  the  trachea.  Next,  the  stimulus  to  respiration 
being  very  much  diminished,  the  respiratory  movements  take  place 
more  slowly  than  usual.  From  these  two  causes  combined,  the 
blood  is  imperfectly  arterialized,  and  the  usual  consequence  of  such 
a  condition  then  follows,  viz.,  a  partial  stagnation  of  the  pulmonary 
circulation.  This  stagnation  still  further  impedes  the  action  of  the 
lungs;  while  it  does  not  excite  the  respiratory  muscles  to  increased 
activity  as  it  would  do  in  health,  owing  to  the  division  of  the  pneu- 
mogastrics. At  the  same  time,  the  accumulation  of  carbonic  acid 
in  the  blood  and  the  tissues  begins  to  exert  a  narcotic  effect,  to 
diminish  the  sensibility  of  the  nervous  centres,  and  consequently 
to  retard  still  more  the  movements  of  respiration.  Thus  all  these 
causes  react  upon  and  aggravate  each  other ;  because  the  connection 
naturally  existing  between  imperfectly  arterialized  blood  and  the 
stimulus  to  respiration,  is  now  destroyed.     The  narcotism  and  pul- 


PNEUMOGASTRIC.  411 

monary  engorgement,  therefore,  continue  to  increase,  until  the  lungs 
are  so  seriously  altered  and  engorged  that  they  are  no  longer  capable 
of  transmitting  the  blood,  and  circulation  and  respiration  come  to 
an  end  at  the  same  time. 

It  must  be  remembered,  also,  that  the  pneumogastric  nerve  has 
other  important  distributions  beside  those  to  the  larynx  and  the 
lungs;  and  the  effect  produced  by  its  division  upon  these  other 
organs  has  no  doubt  a  certain  share  in  producing  the  results  which 
follow.  Bearing  in  mind  the  very  extensive  distribution  of  the 
pneumogastric  nerve  and  the  complicated  character  of  its  func- 
tions, we  may  conclude  that  after  section  of  this  nerve  death  takes 
place  from  a  combination  of  various  causes ;  the  most  active  of 
which  is  a  peculiar  engorgement  of  the  lungs  and  imperfect  per- 
formance of  the  respiratory  function. 

S(o7nach,  and  Digestive  Function. — After  division  of  the  pneumo- 
gastric nerves,  the  sensations  of  hunger  and  thirst  remain,  and  the 
secretion  of  gastric  juice  continues.  Nevertheless  the  digestive 
function  is  disturbed  in  various  ways,  though  not  altogether  abo- 
lished. The  appetite  is  more  or  less  diminished,  as  it  would  be  after 
any  serious  operation,  but  it  remains  sufficiently  active  to  show  that 
its  existence  is  not  directly  dependent  on  the  integrity  of  the  pneu- 
mogastric nerve.  Digestion,  however,  very  seldom  actually  takes 
place  to  any  considerable  extent,  owing  to  the  following  circum- 
stances :  The  animal  is  frequently  seen  to  take  food  and  drink  with 
considerable  avidity;  but  in  a  few  moments  afterward  the  food  and 
drink  are  suddenly  rejected  by  a  peculiar  kind  of  regurgitation. 
This  regurgitation  does  not  resemble  the  action  of  vomiting,  but 
the  substances  swallowed  are  again  discharged  so  easily  and  instan- 
taneously as  to  lead  to  the  belief  that  they  had  never  passed  into 
the  stomach.  Such,  indeed,  is  actually  the  case,  as  any  one  may 
convince  himself  by  watching  the  process,  which  is  often  repeated 
by  the  animal  at  short  intervals.  The  food  and  drink,  taken  volun- 
tarily, pass  down  into  the  oesophagus,  but  owing  to  the  paralysis  of 
the  muscular  fibres  of  this  canal,  are  not  conveyed  into  the  stomach. 
They  accumulate  consequently  in  the  lower  and  middle  part  of  the 
oesophagus ;  and  in  a  few  moments  are  rejected  by  a  sudden  anti- 
staltic  action  of  the  parts,  excited,  apparently,  through  the  influence 
of  the  great  sympathetic. 

The  muscular  coat  of  the  stomach  is  also  paralyzed  to  a  con- 
siderable extent  by  section  of  this  nerve.  Longet  has  shown,  by 
introducing  food  artificially  into  the  stomach,  that  gastric  juice 


412  THE    CRANIAL    NERVES. 

may  be  secreted  and  the  food  be  actually  digested  and  disappear, 
when  introduced  in  small  quantity.  But  when  introduced  in  large 
quantity,  it  remains  undigested,  and  is  found  after  death  with  the 
exterior  of  the  mass  softened  and  permeated  by  gastric  juice,  while 
the  central  portions  are  unaltered,  and  do  not  even  seem  to  have 
come  in  contact  with  the  digestive  fluid.  This  is  undoubtedly 
owing  both  to  the  diminished  sensibility  of  the  mucous  membrane 
of  the  stomach,  and  to  the  paralysis  of  its  muscular  fibres.  The 
peristaltic  action  of  the  organ  is  very  important  in  digestion,  in 
order  to  bring  successive  portions  of  the  food  in  contact  with  the 
mucous  membrane,  and  to  carry  away  such  as  are  already  softened 
or  as  are  not  capable  of  being  digested  in  the  stomach.  This 
constant  movement  and  agitation  of  the  food  is  probably  also  one 
great  stimulus  to  the  continued  secretion  of  the  gastric  juice.  The 
digestive  fluid  will  therefore  be  deficient  in  quantity  after  division 
of  the  pneumogastric  nerves,  at  the  same  time  that  the  peristaltic 
movements  of  the  stomach  are  suspended.  Under  these  circum- 
stances, the  secretion  of  gastric  juice  may  be  sufficient  to  permeate 
and  digest  small  quantities  of  food,  while  a  larger  mass  may  resist 
its  action,  and  remain  undigested.  The  effect  produced  by  division 
of  these  nerves  on  the  digestive,  as  on  the  respiratory  organs,  is 
therefore  of  a  complicated  character,  and  results  from  the  combined 
action  of  several  different  causes,  which  influence  and  modify  each 
other. 

The  effect  produced  upon  the  liver  by  section  of  the  pneumo- 
gastrics,  as  well  as  the  influence  usually  exerted  by  these  nerves 
upon  the  hepatic  functions,  has  been  so  little  studied  that  nothing 
definite  has  been  ascertained  in  regard  to  it.  We  shall  therefore 
pass  over  this  portion  of  the  subject  in  silence. 

That  part  of  the  nervous  system  which  we  have  hitherto 
studied,  viz.,  the  cerebro-spinal  system,  consists  of  an  apparatus  of 
nerves  and  ganglia,  destined  to  bring  the  individual  into  relation 
with  the  external  world.  By  means  of  the  special  senses,  he  is 
made  cognizant  of  sights,  sounds,  and  odors,  by  which  he  is 
attracted  or  repelled,  and  which  guide  him  in  the  pursuit  and 
choice  of  food.  By  the  general  sensations  of  touch  and  the  volun- 
tary movements,  he  is  enabled  to  alter  at  will  his  position  and 
location,  and  to  adapt  them  to  the  varying  conditions  under  which 
he  may  be  placed.  The  great  passages  of  entrance  into  the  body, 
and  of  exit  from  it,  are  guarded  also  by  the  same  portion  of  the 
nervous  system.     The  introduction  of  food  into  the  mouth,  and  its 


PNEUMOGASTRIC.  413 

passage  through  the  oesophagus  to  the  stomach,  are  regulated  by 
the  same  nervous  apparatus ;  and  even  the  passage  of  air  through 
the  larynx,  and  its  penetration  into  the  lungs,  are  equally  under 
the  guidance  of  sensitive  and  motor  nerves  belonging  to  the 
cerebro-spinal  system. 

It  will  be  observed  that  the  above  functions  relate  altogether 
either  to  external  phenomena  or  to  the  simple  introduction  into  the 
body  of  food  and  air,  which  are  destined  to  undergo  nutritive 
changes  in  the  interior  of  the  frame. 

If  we  examine,  however,  the  deeper  regions  of  the  body,  we  find 
located  in  them  a  series  of  internal  phenomena,  relating  only  to 
the  substances  and  materials  which  have  already  penetrated  into 
the  frame,  and  which  form  or  are  forming  a  part  of  its  structure. 
These  are  the  purely  vegetative  functions,  as  they  are  called ;  or 
those  of  growth,  nutrition,  secretion,  excretion,  and  reproduction. 
These  functions,  and  the  organs  to  which  they  belong,  are  not 
under  the  direct  influence  of  the  cerebro-spinal  nerves,  but  are 
regulated  by  another  portion  of  the  nervous  system,  viz.,  the 
"ganglionic  system;"  or,  as  it  is  more  commonly  called,  the  "sys- 
tem of  the  great  sympathetic." 


414  SYSTEM    OF    THE    GREAT    SYMPATHETIC. 


CHAPTER    VI. 

SYSTEM   OF   THE  GREAT   SYMPATHETIC. 

The  sympathetic  system  consists  of  a  double  chain  of  nervous 
ganglia,  running  from  the  anterior  to  the  posterior  extremity  of  the 
body,  along  the  front  and  sides  of  the  spinal  column,  and  connected 
with  each  other  by  slender  longitudinal  filaments.  Each  ganglion 
is  reinforced  by  a  motor  and  sensitive  filament  derived  from  the 
cerebro-spinal  system,  and  thus  the  organs  under  its  influence  are 
brought  indirectly  into  communication  with  external  objects  and 
phenomena.  The  nerves  of  the  great  sympathetic  are  distributed 
to  organs  over  which  the  consciousness  and  the  will  have  no  imme- 
diate control,  as  the  intestine,  kidneys,  heart,  liver,  &c. 

The  first  sympathetic  ganglion  in  the  head  is  the  ophthalmic  gan- 
glion. This  ganglion  is  situated  within  the  orbit  of  the  eye,  on  the 
outer  aspect  of  the  optic  nerve.  It  communicates  by  slender  fila- 
ments with  the  carotid  plexus,  which  forms  the  continuation  of  the 
sympathetic  system  from  below;  and  receives  a  motor  root  from 
the  oculo-motorius  nerve,  and  a  sensitive  root  from  the  ophthalmic 
branch  of  the  5th  pair.  Its  filaments  of  distribution,  known  as  the 
"ciliary  nerves,"  pass  forward  upon  the  eyeball,  pierce  the  sclerotic, 
and  finally  terminate  in  the  iris. 

The  next  division  of  the  great  sympathetic  in  the  head  is  the 
sphenopalatine  ganglion,  situated  in  the  spheno-maxillary  fossa.  It 
communicates,  like  the  preceding,  with  the  carotid  plexus,  and 
receives  a  motor  root  from  the  facial  nerve,  and  a  sensitive  root 
from  the  superior  maxillary  branch  of  the  5th  pair.  Its  filaments 
are  distributed  to  the  levator  palati  and  azygos  uvulae  muscles,  and 
to  the  mucous  membrane  about  the  posterior  nares. 

The  third  sympathetic  ganglion  in  the  head  is  the  submaxillary, 
situated  upon  the  submaxillary  gland.  It  communicates  with  the 
superior  cervical  ganglion  of  the  sympathetic  by  filaments  which 
accompany  the  facial  and  external  carotid  arteries.  It  derives  its 
sensitive  filaments  from  the  lingual  branch  of  the  5th  pair,  and  its 


SYSTEM    OF    THE    GREAT    SYMPATHETIC. 


415 


Fiff.  149. 


motor  filaments  from  the  facial  nerve,  by  means  of  the  chorda 
tympani.  Its  branches  of  distribution  pass  to  the  sides  of  the  tongue 
and  to  the  submaxillary  and  sublingual  glands. 

The  last  sympathetic  ganglion  in  the  head  is  the  otic  ganglion. 
It  is  situated  just  beneath  the 
base  of  the  skull,  on  the  inner 
side  of  the  third  branch  of  the 
trifacial  nerve.  It  sends  fila- 
ments of  communication  to 
the  carotid  plexus;  and  re- 
ceives a  motor  root  from  the 
facial  nerve,  and  a  sensitive 
root  from  the  inferior  maxil- 
lary branch  of  the  5th  pair. 
Its  branches  are  sent  to  the 
internal  muscle  of  the  mal- 
leus in  the  middle  ear  (tensor 
tympani),  and  to  the  mucous 
membrane  of  the  tympanum 
and  Eustachian  tube. 

The  continuation  of  the 
sympathetic  nerve  in  the  neck 
consists  of  two  and  some- 
times of  three  ganglia,  the 
superior,  middle,  and  inferior. 
These  ganglia  communicate 
with  each  other,  and  also 
with  the  anterior  branches 
of  the  cervical  spinal  nerves. 
Their  filaments  follow  the 
course  of  the  carotid  artery 
and  its  branches,  covering 
them  with  a  network  of  inter- 
lacing fibres,  and  are  finally 
distributed  to  the  substance  of 
the  thyroid  gland,  and  to  the 


Course  and  distribution  of  the  Great  Sympa- 
thetic. 


walls  of  the  larynx,  trachea, 

pharynx,  and  oesophagus.  By  the  superior,  middle,  and  inferior 
cardiac  nerves,  they  also  supply  sympathetic  fibres  to  the  cardiac 
plexuses  and  to  the  substance  of  the  heart. 

In  the  chest,  the  ganglia  of  the  sympathetic  nerve  are  situated  on 


416  SYSTEM    OF    THE    GREAT    SYMPATHETIC. 

each  side  the  spinal  column,  just  over  the  heads  of  the  ribs,  with 
which  they  accordingly  correspond  in  number.  Their  communi- 
cations with  the  intercostal  nerves  are  double ;  each  sympathetic 
ganglion  receiving  two  filaments  from  the  intercostal  nerve  next 
above  it.  The  filaments  originating  from  the  thoracic  ganglia  are 
distributed  upon  the  thoracic  aorta,  and  to  the  lungs  and  oesophagus. 
In  the  abdomen,  the  continuation  of  the  sympathetic  system  con- 
sists principally  of  the  aggregation  of  ganglionic  enlargements 
situated  upon  the  cceliac  artery,  known  as  the  semilunar  or  coeliac 
ganglion.  From  this  ganglion  a  multitude  of  radiating  and  inoscu- 
lating branches  are  sent  out,  which,  from  their  diverging  course  and 
their  common  origin  from  a  central  mass,  are  termed  the  "solar 
plexus,"  From  this,  other  diverging  plexuses  originate,  which 
accompany  the  abdominal  aorta  and  its  branches,  and  are  so  dis- 
tributed to  the  stomach,  small  and  large  intestine,  spleen,  pancreas, 
liver,  kidneys,  and  supra-renal  capsules,  and  the  internal  organs  of 
generation. 

Beside  the  above  ganglia  there  are  in  the  abdomen  four  other 
pairs,  situated  in  front  of  the  lumbar  vertebrae,  and  having  similar 
connections  with  those  occupying  the  cavity  of  the  chest.  Their 
filaments  join  the  plexuses  radiating  from  the  semilunar  ganglion. 

In  the  pelvis,  the  sympathetic  system  is  continued  by  four  or  five 
pairs  of  ganglia,  situated  on  the  anterior  aspect  of  the  sacrum,  and 
terminating,  at  the  lower  extremity  of  the  spinal  column,  in  a  single 
ganglion,  the  "  ganglion  impar,"  which  is  probably  to  be  regarded 
as  a  fusion  of  two  separate  ganglia. 

The  entire  sympathetic  series  is  in  this  way  composed  of  nume- 
rous small  ganglia  which  are  connected  throughout,  first,  with  each 
other,  secondly,  with  the  cerebro-spinal  system,  and  thirdly,  with 
the  internal  viscera  of  the  body. 

The  properties  and  functions  of  the  great  sympathetic  have  been 
less  successfully  studied  than  those  of  the  cerebro-spinal  system, 
owing  to  the  anatomical  difficulties  in  the  way  of  reaching  and 
operating  upon  this  nerve  for  purposes  of  experiment.  The  cerebro- 
spinal axis  and  its  nerves  are  easily  exposed  and  subjected  to  exami- 
nation. It  is  also  easy  to  isolate  particular  portions,  and  to  appreciate 
the  disturbances  of  sensation  and  motion  consequent  upon  local 
lesions  or  irritations.  The  phenomena,  furthermore,  which  result 
from  experiments  upon  this  part  of  the  nervous  system,  are  promptly 
produced,  are  well-marked  in  character,  and  are,  as  a  general  rule, 
readily  understood  by  the  experimenter.     On  the  other  hand,  the 


SYSTEM    OP    THE    GREAT    SYMPATHETIC.  417 

principal  part  of  the  sympathetic  system  is  situated  in  the  interior 
of  the  chest  and  abdomen ;  and  the  mere  operation  of  opening  these 
cavities,  so  as  to  reach  the  ganglionic  centres,  causes  such  a  disturb- 
ance in  the  functions  of  vital  organs,  and  such  a  shock  to  the  system 
at  large,  that  the  results  of  these  experiments  have  been  always 
more  or  less  confused  and  unsatisfactory.  Furthermore,  the  con- 
nections of  the  sympathetic  ganglia  Avith  each  other  and  with  the 
cerebro-spinal  axis  are  so  numerous  and  scattered,  that  these  ganglia 
cannot  be  completely  isolated  without  resorting  to  an  operation  still 
more  mutilating  and  injurious  in  its  character.  And  finally,  the 
sensible  phenomena  which  are  obtained  from  experimenting  on  the 
great  sympathetic  are,  in  the  majority  of  cases,  slow  in  making 
their  appearance,  and  not  particularly  striking  or  characteristic  in 
their  nature. 

Notwithstanding  these  difficulties,  however,  some  facts  have  been 
ascertained  with  regard  to  this  part  of  the  nervous  system,  which 
give  us  a  certain  degree  of  insight  into  its  character  and  functions. 

The  great  sympathetic  is  endowed  both  with  sensibility  and  the 
power  of  exciting  motion;  but  these  properties  are  less  active 
here  than  in  the  cerebro-spinal  system,  and  are  exercised  in  a  dif- 
ferent manner.  If  we  irritate,  for  example,  a  sensitive  nerve  in 
one  of  the  extremities,  or  apply  the  galvanic  current  to  the  poste- 
rior root  of  a  spinal  nerve,  the  evidences  of  pain  or  of  reflex 
action  are  acute  and  instantaneous.  There  is  no  appreciable  inter- 
val between  the  application  of  the  stimulus  and  the  sensations 
which  result  from  it.  On  the  other  hand,  experimenters  who  have 
operated  upon  the  sympathetic  ganglia  and  nerves  of  the  chest  and 
abdomen  find  that  evidences  of  sensibility  are  distinctly  manifested 
here  also,  but  less  acutely  and  only  after  somewhat  prolonged  ap- 
plication of  the  irritating  cause.  These  results  correspond  very 
closely  with  what  we  know  of  the  vital  properties  of  the  organs 
which  are  supplied  either  principally  or  exclusively  by  the  sympa- 
thetic; as  the  liver,  intestine,  kidneys,  &c.  These  organs  are 
insensible,  or  nearly  so,  to  ordinary  impressions.  We  are  not  con- 
scious of  the  changes  and  operations  going  on  in  them,  so  long  as 
these  changes  and  operations  retain  their  normal  character.  But 
they  are  still  capable  of  perceiving  unusual  or  excessive  irritations, 
and  may  even  become  exceedingly  painful,  when  in  a  state  of  in- 
flammation. 

There  is  the  same  peculiar  character  in  the  action  of  the  motor 
nerves  belonging  to  the  sympathetic.     If  the  facial  or  sublingual, 
27 


418  SYSTEM    OF    THE    GREAT    SYMPATHETIC. 

or  the  anterior  root  of  a  spinal  nerve  be  irritated,  the  convulsive 
movement  which  follows  is  instantaneous,  violent,  and  only  mo- 
mentary in  its  duration.  But  if  the  semilunar  ganglion  or  its 
nerves  be  subjected  to  a  similar  experiment,  no  immediate  effect  is 
produced.  It  is  only  after  a  few  seconds  that  a  slow,  vermicular, 
progressive  contraction  takes  place  in  the  corresponding  part  of  the 
intestine,  which  continues  for  some  time  after  the  exciting  cause 
has  been  removed. 

Morbid  changes  taking  place  in  organs  supplied  by  the  sympa- 
thetic present  a  similar  peculiarity  in  the  mode  of  their  produc- 
tion. If  the  body  be  exposed  to  cold  and  dampness,  for  example, 
congestion  of  the  kidneys  shows  itself  perhaps  on  the  following 
(lay.  Inflammation  of  any  of  the  internal  organs  is  very  rarely 
established  within  twelve  or  twenty-four  hours  after  the  application 
of  the  exciting  cause.  The  internal  processes  of  nutrition  together 
with  their  derangements,  which  are  regarded  as  especially  under 
the  control  of  the  great  sympathetic,  always  require  a  longer  time 
to  be  influenced  by  incidental  causes,  than  those  which  are  regulated 
by  the  nerves  and  ganglia  of  the  cerebro-spinal  system. 

In  the  head,  the  sympathetic  has  a  close  and  important  connec- 
tion with  the  exercise  of  the  special  senses.  This  is  illustrated 
more  particularly,  in  the  case  of  the  eye,  by  its  influence  over  the 
alternate  expansion  and  contraction  of  the  pupil.  The  ophthalmic 
ganglion  sends  off  a  number  of  ciliary  nerves,  which  are  distributed 
to  the  iris.  It  is  connected,  as  we  have  seen,  with  the  remaining 
sympathetic  ganglia  in  the  head,  and  receives,  beside,  a  sensitive 
root  from  the  ophthalmic  branch  of  the  5th  pair,  and  a  motor  root 
from  the  oculo-motorius.  The  reflex  action  by  which  the  pupil 
contracts  under  a  strong  light  falling  upon  the  retina,  and  expands 
under  a  diminution  of  light,  takes  place  accordingly  through  this 
ganglion.  The  impression  conveyed  by  the  optic  nerve  to  the 
tubercula  quadrigemina,  and  reflected  outward  by  the  fibres  of 
the  oculo-motorius,  is  not  transmitted  directly  by  the  last  named 
nerve  to  the  iris ;  but  passes  first  to  the  ophthalmic  ganglion,  and 
is  thence  conveyed  to  its  destination  by  the  ciliary  nerves. 

The  reflex  movements  of  the  iris  exhibit  consequently  a  some- 
what sluggish  character,  which  indicates  the  intervention  of  a  part 
of  the  sympathetic  system.  The  changes  in  the  size  of  the  pupil 
do  not  take  place  instantaneously,  with  the  variation  in  the  amount 
of  light,  but  always  require  an  appreciable  interval  of  time.  If 
we  pass  suddenly  from  a  brilliantly  lighted  apartment  into  a  dark 


SYSTEM    OF    THE    GREAT    SYMPATHETIC.  419 

room,  we  are  unable  to  distinguish  surrounding  objects  until  a 
certain  time  has  elapsed,  and  the  expansion  of  the  pupil  has  taken 
place;  and  vision  even  continues  to  grow  more  and  more  distinct 
for  a  considerable  period  afterward,  as  the  expansion  of  the  pupil 
becomes  more  complete.  Again,  if  we  cover  the  eyes  of  another 
person  with  the  hand  or  a  folded  cloth,  and  then  suddenly  expose 
them  to  the  light,  we  shall  find  that  the  pupil,  which  is  at  first  dilated, 
contracts  somewhat  rapidly  to  a  certain  extent,  and  afterward  con- 
tinues to  diminish  in  size  during  several  seconds,  until  the  proper 
equilibrium  is  fairly  established.  Furthermore,  if  we  pass  sud 
denly  from  a  dark  room  into  the  bright  sunshine,  we  are  immedi- 
ately conscious  of  a  painful  sensation  in  the  eye,  which  lasts  for  a 
considerable  time ;  and  which  results  from  the  inability  of  th^- 
pupil  to  contract  with  sufficient  rapidity  to  shut  out  the  excessive 
amount  of  light.  All  such  exposures  should  be  made  gradually, 
so  that  the  movements  of  the  iris  may  keep  pace  with  the  varying 
quantity  of  stimulus,  and  so  protect  the  eye  from  injurious  impres- 
sions. 

The  reflex  movements  of  the  iris,  however,  though  accomplished 
through  the  medium  of  the  ophthalmic  ganglion,  derive  their 
original  stimulus,  through  the  motor  root  of  this  ganglion,  from 
the  oculo-motorius  nerve.  For  it  has  been  found  that  if  the  last 
mentioned  nerve  be  divided  between  the  brain  and  the  eyeball, 
the  pupil  becomes  immediately  dilated,  and  will  no  longer  contract 
under  the  influence  of  light.  The  motive  power  originally  derived 
from  the  brain  is,  therefore,  in  the  case  of  the  iris,  modified  by 
passing  through  one  of  the  sympathetic  ganglia  before  it  reache& 
its  final  destination. 

An  extremely  interesting  fact  in  this  connection  is  the  following: 
Of  the  three  organs  of  special  sense  in  the  head,  viz.,  the  eye,  the 
nose,  and  the  ear,  each  one  is  provided  with  two  sets  of  muscles, 
superficial  and  deep,  which  together  regulate  the  quantity  of  stimu- 
lus admitted  to  the  organ.  The  superficial  set  of  these  muscles  is 
animated  by  branches  of  the  facial  nerve ;  the  deep  seated  or  in- 
ternal set,  by  filaments  from  a  sympathetic  ganglion. 

Thus,  the  front  of  the  eyeball  is  protected  by  the  orbicularis  and 
levator  palpebrae  superioris  muscles,  which  open  or  close  the  eye- 
lids at  will,  and  allow  a  larger  or  smaller  quantity  of  light  to  reach 
the  cornea.  These  muscles  are  supplied  by  the  oculo-motorius  and 
facial  nerves,  and  are  for  the  most  part  voluntary  in  their  action. 
The  iris,  on  the  other  hand,  is   a   more  deeply-seated  muscular 


420  SYSTEM    OF    THE    GREAT    SYMPATHETIC. 

curtain,  winch  regulates  the  quantity  of  light  admitted  through  the 
pupil.  It  is  supplied,  as  we  have  seen,  by  filaments  from  the 
ophthalmic  ganglion,  and  its  movements  are  altogether  involuntary 
in  character. 

In  the  olfactory  apparatus,  the  anterior  or  superficial  set  of 
muscles  are  the  compressors  and  elevators  of  the  alse  nasi,  which 
are  animated  by  filaments  of  the  facial  nerve.  By  their  action, 
odoriferous  vapors,  when  faint  and  delicate  in  their  character,  are 
snuffed  up  and  directed  into  the  upper  part  of  the  nasal  passages, 
where  they  come  in  contact  with  the  most  sensitive  portions  of  the 
olfactory  membrane ;  or,  if  too  pungent  or  disagreeable  in  flavor, 
are  excluded  from  entrance.  These  muscles  are  not  very  im- 
portant or  active  in  the  human  subject;  but  in  many  of  the  lower 
animals  with  a  more  active  and  powerful  sense  of  smell,  as  for 
example  the  carnivora,  they  may  be  seen  to  play  a  very  important 
part  in  the  mechanism  of  olfaction.  Furthermore,  the  levators  and 
depressors  of  the  velum  palati,  which  are  more  deeply  situated, 
serve  to  open  or  close  the  orifice  of  the  posterior  nares,  and  accom- 
plish a  similar  office  with  the  muscles  already  named  in  front. 
The  levator  palati  and  azygos  uvulae  muscles,  which,  by  their 
action,  tend  to  close  the  posterior  nares,  are  supplied  by  filaments 
from  the  spheno-palatine  ganglion,  and  are  involuntary  in  their 
character. 

The  ear  has  two  similar  sets  of  muscles,  similarly  supplied.  The 
first,  or  superficial  set,  are  those  moving  the  external  ear,  viz.,  the 
anterior,  superior,  and  posterior  auriculares.  Like  the  muscles  of 
the  anterior  nares,  they  are  comparatively  inactive  in  man,  but 
in  many  of  the  lower  animals  are  well  developed  and  important. 
In  the  horse,  the  deer,  the  sheep,  &c.,  they  turn  the  ear  in  various 
directions  so  as  to  catch  more  distinctly  faint  and  distant  sounds,  or 
to  exclude  those  which  are  harsh  and  disagreeable.  These  muscles 
are  supplied  by  filaments  of  the  facial  nerve,  and  are  voluntary  in 
their  action. 

The  deep  seated  set  are  the  muscles  of  the  middle  ear.  In 
order  to  understand  their  action,  we  must  recollect  that  sounds 
are  transmitted  from  the  external  to  the  middle  ear  through  the 
membrane  of  the  tympanum,  which  vibrates,  like  the  head  of  a 
drum,  on  receiving  sonorous  impulses  from  without.  Now  it  is 
well  known  that  any  resonant  membrane  or  cord  is  capable  of 
vibrating  in  unison  with  acute  or  grave  sounds,  according  to  its 
fctate  of  tension  or  relaxation.     For  any  such  membrane  or  cord,  at 


SYSTEM    OF    THE    GREAT    SYMPATHETIC.  421 

a  given  degree  of  tension,  there  is  a  limit  both  to  the  gravity  and 
acuteness  of  the  sounds  which  it  is  capable  of  transmitting.  The 
greater  its  tension,  the  more  acute  the  sounds  which  may  be  trans- 
mitted ;  the  lower  its  tension,  the  deeper  the  sounds  to  which  it 
is  capable  of  vibrating.  Furthermore,  any  elastic  membrane  is 
more  easily  thrown  into  sonorous  vibrations  when  in  a  tense  con- 
dition, and  is  consequently  more  capable,  when  tightly  strained,  of 
receiving  and  transmitting  sounds  of  feeble  intensity. 

The  membrane  of  the  tympanum,  accordingly,  which  is  an 
elastic  sheet  stretched  across  the  passage  to  the  ear,  may  be  made 
more  or  less  sensitive  to  sonorous  impressions  by  varying  its  con- 
dition of  tension  or  relaxation.  The  handle  of  the  malleus  is 
attached  to  the  membrana  tympani  in  such  a  manner  that  when 
the  internal  muscle  of  the  malleus  (tensor  tympani)  is  thrown  into 
contraction,  the  tympanic  membrane  is  drawn  inward,  and  its 
tension  increased.  On  the  relaxation  of  this  muscle,  the  chain  of 
bones  of  the  middle  ear  returns  to  its  ordinary  position  by  the 
elasticity  of  its  ligaments,  and  restores  the  previous  condition  of 
the  membrana  tympani.  It  is  undoubtedly  by  this  mechanism  that 
the  sensibility  of  the  hearing  is  increased  or  diminished  according 
to  circumstances.  In  listening  attentively  to  a  very  faint  sound,  or 
in  endeavoring  to  distinguish  slight  variations  at  a  high  pitch,  a 
sense  of  exertion  may  be  almost  always  perceived,  which  is  proba- 
bly due  in  a  great  degree  to  the  unusual  tension  of  the  membrana 
tympani.  On  the  other  hand,  sounds  of  a  very  sharp  and  acute 
character  are  distressing  to  the  ear,  and  may  be  diminished  in 
apparent  intensity  by  a  relaxation  of  the  same  membrane.  The 
internal  muscle  of  the  malleus,  by  which  this  action  is  accom- 
plished, corresponds  therefore  in  its  office  with  the  muscular  fibres 
of  the  iris,  and  to  those  which  open  and  close  the  posterior  nares. 
It  is  supplied  by  filaments  from  the  otic  ganglion,  the  fourth  in  the 
series  of  sympathetic  ganglia  situated  in  the  head. 

In  all  these  instances,  the  reflex  action  taking  place  in  the 
deeper  seated  muscles,  originates  from  a  sensation  which  is  con- 
veyed inward  to  the  cerebro-spinal  centres,  and  is  then  transmitted 
outward  to  its  final  destination  through  the  medium  of  one  of  the 
sympathetic  ganglia. 

Another  very  striking  fact  concerning  the  sympathetic  relates  to 
the  changes  produced  by  its  division,  in  the  nutritive  processes  of 
the  parts  supplied  by  it.  One  of  the  most  important  and  remark- 
able of  these  changes  is  an  elevation  of  temperalure  in  the  affected 


422  SYSTEM    OF    THE    GREAT    SYMPATHETIC. 

parts.  If  the  sympathetic  nerve  be  divided  on  one  side  of  the  neck, 
in  the  rabbit,  cat,  or  dog,  an  elevation  of  temperature  begins  to  be 
perceptible  on  the  corresponding  side  of  the  head  in  a  very  short 
time.  In  the  cat,  we  have  found  a  very  sensible  difference  in  tem- 
perature between  the  two  sides  at  the  end  of  five  or  ten  minutes ; 
and  in  the  rabbit,  at  the  end  of  half  an  hour.  A  vascular  conges- 
tion of  the  parts  also  takes  place,  which  may  be  seen  to  great 
advantage  in  the  ear  of  the  rabbit,  when  held  up  between  the  eye 
and  the  light.  The  elevation  of  temperature,  in  these  cases,  is  very 
perceptible  to  the  touch,  and  may  be  also  measured  by  the  thermo- 
meter. Bernard'  has  found  it  to  reach  8°  or  9°  F.  The  elevation 
<)f  temperature  and  congested  state  of  the  parts  are  sometimes  found 
to  be  diminished  by  the  next  day,  and  afterward  disappear  rapidly. 
Occasionally,  however,  they  last  for  a  long  time.  Bernard  {op.  cit.) 
has  seen  the  unnatural  temperature  of  the  affected  parts  remain  in 
the  rabbit  for  fifteen  to  eighteen  days,  and  in  the  dog  for  two 
months.  Where  the  superior  cervical  ganglion  has  been  extir- 
pated, he  has  even  found  the  above  appearances  to  continue  in  the 
<log  for  a  year  and  a  half.  They  may  also,  according  to  the  same 
authority,  be  reproduced  several  times  in  the  same  animal,  by 
repeated  divisions  of  the  sympathetic  nerve. 

The  above  effects  are  due  to  a  peculiar  modification  in  the  nutri- 
tion of  the  affected  parts,  which  has  some  analogy  with  inflamma- 
tion. The  unnatural  heat,  the  congestion,  and  the  increased  sensi- 
bility which,  are  present,  all  serve  to  indicate  a  certain  resemblance 
between  the  two  conditions.  None  of  the  more  serious  consequences 
of  inflammation,  however,  such  as  oedema,  exudation,  sloughing  or 
ulceration,  have  ever  been  known  to  follow  from  this  operation ; 
and  the  term  inflammation,  accordingly,  cannot  properly  be  applied 
to  its  results. 

Division  of  the  sympathetic  nerve  in  the  middle  of  the  neck 
has  also  a  very  singular  and  instantaneous  effect  on  the  muscular 
apparatus  of  the  eye.  Within  a  very  few  seconds  after  the  above 
operation  has  been  performed  upon  the  cat,  the  pupil  of  the  cor- 
responding eye  becomes  strongly  contracted,  and  remains  in  that 
condition.  At  the  same  time  the  third  eyelid,  or  "nictitating  mem- 
brane," with  which  these  animals  are  provided,  is  drawn  partially 
over  the  cornea,  and  the  upper  and  lower  eyelids  also  approxi- 
mate very  considerably  to  each  other;  so  that  all  the  apertures 

'  Reclierches  experimentales  sur  le  Grand  Sympatliique.     Paris,  1854. 


SYSTEM    OF    TPIE    GREAT    SYMPATHETIC. 


423 


Fiff.  150. 


Cat,  after  section  of  the  right  sympathetic. 


guarding  the  eyeball  are  very  perceptibly  narrowed,  and  the  ex- 
pression of  the  face  on  that  side  is  altered  in  a  corresponding  degree. 
This  effect  upon  the  pupil  has  been  explained  by  supposing  the 
circular  fibres  of  the  iris,  or  the 
constrictors  of  the  pupil,  to  be 
.inimated  exclusively  by  nervous 
filaments  derived  from  the  oculo- 
motorius ;  and  the  radiating  fibres, 
or  the  dilators,  to  be  supplied  by 
the  sympathetic.  Accordingly, 
while  division  of  the  oculo-mo- 
torius  would  produce  dilatation 
of  the  pupil  (as  it  actually  does), 
by  paralysis  of  the  circular  fibres 
only,  division  of  the  sympathetic 
would  be  followed  by  exclusive 
paralysis  of  the  dilators,  and  a  per- 
manent contraction  of  the  pupil  would  consequently  take  place.  The 
above  explanation,  however,  is  not  a  satisfactory  one ;  since  after 
division  of  the  sympathetic  nerve  in  the  cat,  as  we  have  already 
shown,  not  only  is  the  pupil  contracted,  but  both  the  upper  and  lower 
eyelids  and  the  nictitating  membrane  are  also  partially  drawn  over 
the  cornea,  and  assist  in  excluding  the  light.  The  last-named  effect 
cannot  be  owing  to  any  direct  paralysis,  from  division  of  the  fibres 
of  the  sympathetic.  It  is  more  probable  that  the  section  of  this 
nerve  operates  simply  by  exaggerating  for  a  time  the  sensibility  of 
the  retina,  as  it  does  that  of  the  integument ;  and  that  the  partial 
closure  of  the  eyelids  and  pupil  is  a  secondary  consequence  of  that 
condition. 

It  will  be  remembered  that  in  describing  the  inflammation  of  the 
eyeball,  consequent  upon  section  of  the  fifth  pair  of  nerves,  we 
found  that  there  were  reasons  for  believing  this  effect  to  be  due  to 
injury  of  certain  sympathetic  fibres  which  accompany  the  fifth  pair. 
If  the  fifth  pair  in  fact  be  divided  at  the  level  of  the  Casserian  gan- 
glion, where  it  is  joined  by  sympathetic  fibres  from  the  carotid 
plexus,  or  between  this  ganglion  and  the  eyeball,  a  destructive 
inflammation  of  the  organ  follows.  But  if  the  section  be  made 
behind  the  ganglion,  so  as  to  avoid  the  filaments  of  communication 
with  the  sympathetic,  no  inflammatory  change  takes  place.  If  this 
fact  be  really  owing  to  the  presence  of  s^^mpathetic  fibres  which 


424  SYSTEM    OF    THE    GKEAT    SYMPATHETIC. 

accompany  the  fifth  pair,  it  indicates  a  remarkable  difference  in  the 
effects  of  dividing  the  sympathetic  near  the  eyeball  and  at  a  dis- 
tance from  it ;  since  no  real  inflammation  of  the  eyeball  or  its 
appendages  is  ever  produced  by  division  of  this  nerve  in  the  middle 
of  the  neck,  but  only  the  elevation  of  temperature  and  increase  of 
sensibility  which  have  been  already  described. 

The  influence  of  the  sympathetic  nerve  and  the  consequences 
of  its  division  upon  the  thoracic  and  abdominal  viscera  have  been 
only  very  imperfectly  investigated  by  experimental  methods.  It 
undoubtedly  serves  as  a  medium  of  reflex  action  between  the  sensi- 
tive and  motor  portions  of  the  digestive,  excretory,  and  generative 
apparatuses ;  and  it  is  certain  that  it  also  takes  part  in  reflex  actions 
in  which  the  cerebro-spinal  system  is  at  the  same  time  interested. 
There  are  accordingly  three  different  kinds  of  reflex  action,  taking 
place  wholly  or  partially  through  the  sympathetic  system,  which 
may  be  observed  to  occur  in  the  living  body. 

1st.  Refiex  actions  taking  place  from  the  irdernal  organs,  through  the 
sym.pathetic  and  cerebro-spinal  systems,  to  the  voluntary  muscles  and 
sensitive  surfaces. — The  convulsions  of  young  children  are  often 
owing  to  the  irritation  of  the  undigested  food  in  the  intestinal  canal. 
Attacks  of  indigestion  are  also  known  to  produce  temporary  amau- 
rosis, double  vision,  strabismus,  and  even  hemiplegia.  Nausea,  and 
a  diminished  or  capricious  appetite,  are  often  prominent  symptoms 
of  early  pregnancy,  induced  by  the  peculiar  condition  of  the  uterine 
mucous  membrane. 

2d.  Reflex  actions  taking  place  from  the  sensitive  surfaces,  through 
the  cerebro-spinal  and  sympathetic  systems,  to  the  involuntary  muscles 
and  secreting  organs. — Imprudent  exposure  of  the  integument  to 
cold  and  wet,  will  often  bring  on  a  diarrhoea.  Mental  and  moral 
impressions,  conveyed  through  the  special  senses,  will  affect  the 
motions  of  the  heart,  and  disturb  the  processes  of  digestion  and 
secretion.  Terror,  or  an  absorbing  interest  of  any  kind,  will  pro- 
duce a  dilatation  of  the  pupil,  and  communicate  in  this  way  a  pecu- 
liarly wild  and  unusual  expression  to  the  eye.  Disagreeable  sights 
or  odors,  or  even  unpleasant  occurrences,  are  capable  of  hastening 
or  arresting  the  menstrual  discharge,  or  of  inducing  premature 
delivery. 

3d.  Refiex  actions  taking  place  through  the  sympathetic  system  from 
one  part  of  the  internal  organs  to  another. -^The  contact  of  food  with 
the  mucous  membrane  of  the  small  intestine  excites  a  peristaltic 


SYSTEM    OF    THE    GREAT    SYMPATHETIC.  4'25 

movement  in  the  muscular  coat.  The  mutual  action  of  the  digestive, 
urinary,  and  internal  generative  organs  upon  each  other  takes  place 
entirely  through  the  medium  of  the  sympathetic  ganglia  and  their 
nerves.  The  variations  of  the  capillary  circulation  in  different 
abdominal  viscera,  corresponding  with  the  state  of  activity  or  re- 
pose of  their  associated  organs,  are  to  be  referred  to  a  similar 
nervous  influence.  These  phenomena  are  not  accompanied  by  anv 
consciousness  on  the  part  of  the  individual,  nor  by  any  apparent 
intervention  of  the  cerebro-spinal  system. 


SECTION  III. 
HEPRODUCTION. 


CHAPTER    I. 

ON    THE    NATURE    OF    REPRODUCTION,    AND    THE 
ORIGIN   OF   PLANTS   AND   ANIMALS. 

The  process  of  reproduction  is  the  most  characteristic,  and  in 
many  respects  the  most  interesting,  of  all  the  phenomena  presented 
by  organized  bodies.  It  includes  the  whole  history  of  the  changes 
taking  place  in  the  organs  and  functions  of  the  individual  at  suc- 
cessive periods  of  life,  as  well  as  the  production,  growth,  and  de- 
velopment of  the  new  germs  which  make  their  appearance  by 
iieneration. 

For  all  organized  bodies  pass  through  certain  well  defined  epochs 
or  phases  of  development,  by  which  their  structure  and  functions 
undergo  successive  alterations.  We  have  already  seen  that  the 
living  animal  or  plant  is  distinguished  from  inanimate  substances 
by  the  incessant  changes  of  nutrition  and  growth  which  take  place 
in  its  tissues.  The  muscles  and  the  mucous  membranes,  the  osse- 
ous and  cartilaginous  tissues,  the  secreting  and  circulatory  organs, 
all  incessantly  absorb  oxygen  and  nutritious  material  from  with- 
out, and  assimilate  their  molecules;  while  new  substances,  produced 
by  a  retrogressive  alteration  and  decomposition,  are  at  the  same 
time  excreted  and  discharged.  These  nutritive  changes  correspond 
in  rapidity  with  the  activity  of  the  other  vital  phenomena ;  since 
the  production  of  these  phenomena,  and  the  very  existence  of  the 
vital  functions,  depend  upon  the  regular  and  normal  continuance 
of  the  nutritive  process.  Thus  the  organs  and  tissues,  which  are 
always  the  seat  of  this  double  change  of  renovation  and  decay, 
retain  nevertheless  their  original  constitution,  and  continue  to  be 
capable  of  exhibiting  the  vital  phenomena. 


428  NATURE    OF    REPRODUCTIOISr. 

The  above  changes,  however,  are  not  in  reality  the  only  ones 
which  talce  place.  For  although  the  structure  of  the  body  and  the 
composition  of  its  constituent  parts  appear  to  be  maintained  in  an 
unaltered  condition,  by  the  nutritive  process,  from  one  moment  to 
another,  or  from  day  to  day,  yet  a  comparative  examination  of 
them  at  greater  intervals  of  time  will  show  that  this  is  not  pre- 
cisely the  case;  but  that  the  changes  of  nutrition  are,  in  point  of 
fact,  progressive  as  well  as  momentary.  The  composition  and  pro- 
perties of  the  skeleton,  for  example,  are  not  the  same  at  the  age  of 
twenty-five  that  they  were  at  fifteen.  At  the  latter  period  it  con- 
tains more  calcareous  and  less  organic  matter  than  before ;  and  its 
solidity  is  accordingly  increased,  while  its  elasticity  is  diminished. 
Even  the  anatomy  of  the  bones  alters  in  an  equally  gradual  manner; 
the  medullary  cavities  enlarging  with  the  progress  of  growth,  and 
the  cancellated  tissue  becoming  more  open  and  spongy  in  texture. 
We  have  already  noticed  the  difference  in  the  quantity  of  oxygen 
and  carbonic  acid  inspired  and  exhaled  at  different  ages.  The 
muscles,  also,  if  examined  after  the  lapse  of  some  years,  are  found 
to  be  less  irritable  than  formerly,  owing  to  a  slow,  but  steady  and 
permanent  deviation  in  their  intimate  constitution. 

The  vital  properties  of  the  organs,  therefore,  change  with  their 
varying  structure;  and  a  time  comes  at  last  when  they  are  per- 
ceptibly less  capable  of  performing  their  original  functions  than 
before.  This  alteration  being  dependent  on  the  varying  activity  of 
the  nutritive  process,  continues  necessarily  to  increase.  The  very 
exercise  of  the  vital  powers  is  inseparably  connected  with  the  sub- 
sequent alteration  of  the  organs  employed  in  them ;  and  the  func- 
tions of  life,  therefore,  instead  of  remaining  indefinitely  the  same, 
pass  through  a  series  of  successive  changes,  which  finally  terminate 
in  their  complete  cessation. 

The  history  of  a  living  animal  or  plant  is,  therefore,  a  history  of 
successive  epochs  or  phases  of  existence,  in  each  of  which  the  struc- 
ture and  functions  of  the  body  differ  more  or  less  from  those  in 
every  other.  Every  living  being  has  a  definite  term  of  life,  through 
which  he  passes  by  the  operation  of  an  invariable  law,  and  which, 
at  some  regularly  appointed  time,  comes  to  an  end.  The  plant 
germinates,  grows,  blossoms,  bears  fruit,  withers,  and  decays.  The 
animal  is  born,  nourished  and  brought  to  maturity,  after  which  he 
retrogrades  and  dies.  The  very  commencement  of  existence,  by 
leading  through  its  successive  intermediate  stages,  conducts  at  last 
necessarily  to  its  own  termination. 


NATURE    OF    REPRODUCTION.  429 

But  while  individual  organisms  are  thus  constantly  perishing  and 
disappearing  from  the  stage,  the  particular  kind,  or  species^  remains 
in  existence,  apparently  without  any  important  change  in  the  cha- 
racter or  appearance  of  the  organized  forms  belonging  to  it.  The 
horse  and  the  ox,  the  pine  and  the  palm-tree,  the  different  kinds  of 
wild  and  domesticated  animals,  even  the  different  races  of  man 
himself,  have  remained  without  any  essential  alteration  ever  since 
the  earliest  historical  epochs.  Yet  during  this  period  innumerable 
individuals,  belonging  to  each  species  or  race,  must  have  lived 
through  their  natural  terin  and  successively  passed  out  of  existence. 
A  species  may  therefore  be  regarded  as  a  type  or  class  of  organized 
beings,  in  which  the  particular  forms  or  structures  composing  it  die 
off  constantly  and  disappear,  but  which  nevertheless  repeats  itself 
from  year  to  year,  and  maintains  its  ranks  constantly  full  by  the 
regular  accession  of  new  individuals.  This  process,  by  which  new 
organisms  make  their  appearance,  to  take  the  place  of  those  which 
are  destroyed,  is  known  as  the  process  of  reproduction  or  generation. 
Let  us  now  see  in  what  manner  it  is  accomplished. 

It  has  always  been  known  that,  as  a  general  rule  in  the  process 
of  generation,  the  young  animals  or  plants  are  produced  directly 
from  the  bodies  of  the  elder.  The  relation  between  the  two  is  that 
of  parents  and  progeny ;  and  the  new  organisms,  thus  generated, 
become  in  turn  the  parents  of  others  who  succeed  them.  For  this 
reason  wherever  such  plants  or  animals  exist,  they  indicate  the 
previous  existence  of  others  belonging  to  the  same  species;  and  if 
by  any  accident  the  whole  species  should  be  destroyed  in  any  par- 
ticular locality,  no  new  individuals  could  be  produced  there,  unless 
by  the  previous  importation  of  others  of  the  same  kind. 

The  commonest  observation  shows  this  to  be  true  in  regard  to 
those  animals  and  plants  with  whose  history  we  are  more  familiarly 
acquainted.  An  opinion,  however,  has  sometimes  been  maintained 
that  there  are  exceptions  to  this  rule  ;  and  that  living  beings  may, 
under  certain  circumstances,  be  produced  from  inanimate  substances, 
without  any  similar  plants  or  animals  having  preceded  them  ;  pre- 
senting, accordingly,  the  singular  phenomenon  of  a  progeny  without 
parents.  Such  a  production  of  organized  bodies  is  known  by  the 
name  oi  spontaneous  generation.  It  is  believed  by  the  large  majority 
of  physiologists  at  the  present  day  that  no  such  spontaneous  gene- 
ration ever  takes  place;  but  that  plants  and  animals  are  always 
derived,  by  direct  reproduction,  from  previously  existing  parents 
of  the  same  species.     As  this,  however,  is  a  question  of  some  im- 


430  NATURE    OF    REPRODUCTION. 

portance,  and  one  which  has  been  frequently  discussed  in  works  on 
physiology,  we  shall  proceed  to  pass  in  review  the  facts  which  have 
been  adduced  in  favor  of  the  occurrence  of  spontaneous  generation, 
as  well  as  those  which  would  lead  to  its  disproval  and  rejection. 

It  is  evident,  in  the  first  place,  that  many  apparent  instances  of 
spontaneous  generation  are  found  to  be  of  a  very  different  character 
so  soon  as  they  are  subjected  to  a  critical  examination.  Thus  grass- 
hoppers and  beetles,  earthworms  and  crayfish,  the  swarms  of  minute 
insects  that  fill  the  air  over  the  surface  of  stagnant  pools,  and  even 
frogs,  moles,  and  lizards,  have  been  supposed  in  former  times  to  be 
generated  directly  from  the  earth  or  the  atmosphere ;  and  it  was 
only  by  investigating  carefully  the  natural  history  of  these  animals 
that  they  were  ascertained  to  be  produced  in  the  ordinary  manner 
by  generation  from  parents,  and  were  found  to  continue  the  repro- 
duction of  their  species  in  the  same  way.  A  still  more  striking 
instance  is  furnished  by  the  production  of  maggots  in  putrefying 
meat,  vegetables,  flour  paste,  fermenting  dung,  &c.  If  a  piece  of 
meat  be  exposed,  for  example,  and  allowed  to  undergo  the  process 
of  putrefaction,  at  the  end  of  a  few  days  it  will  be  found  to  contain 
a  multitude  of  living  maggots,  which  feed  upon  the  decomposing 
flesh.  Now  these  maggots  are  always  produced  under  the  same 
conditions  of  warmth,  moisture  and  exposure,  and  at  the  same  stage 
of  the  putrefactive  process.  They  are  never  to  be  found  in  fresh 
meat,  nor,  in  fact,  in  any  other  situation  than  the  one  just  mentioned. 
They  appear,  consequently,  without  any  similar  individuals  having 
existed  in  the  same  locality ;  and  considering  the  regularity  of  their 
appearance  under  the  given  conditions,  and  their  absence  elsewhere, 
it  has  been  believed  that  they  were  spontaneously  generated,  under 
the  influence  of  warmth,  moisture,  and  the  atmosphere,  from  the 
decaying  organic  substances. 

A  little  examination,  however,  discovers  a  very  simple  solution 
of  the  foregoing  difficulty.  On  watching  the  exposed  animal  or 
vegetable  substances  during  the  earlier  periods  of  their  decompo- 
sition, it  is  found  that  flies  and  other  insects,  attracted  by  the  odor 
of  the  decaying  material,  hover  round  it  and  deposit  their  eggs 
upon  its  surface  or  in  its  interior.  These  eggs,  hatched  by  the 
warmth  to  which  they  are  exposed,  produce  the  maggots ;  which 
are  simply  the  young  of  the  winged  insects,  and  which  after  a  time 
become  transformed,  by  the  natural  progress  of  development,  into 
perfect  insects  similar  to  their  parents.  The  difficulty  of  account- 
ing for  the  presence  of  the  maggots  by  generation,  therefore,  de- 


IXFUSORIAL    ANIMALCULES.  431 

pended  simply  on  the  fact  that  thej  were  different  in  appearance 
from  the  parents  that  produced  them.  This  difference,  however,  is 
merely  a  temporary  one,  corresponding  with  the  difference  in  age, 
and  disappears  when  the  development  of  the  animal  is  complete ; 
just  as  the  young  chicken,  when  recently  hatched,  has  a  different 
form  and  plumage  from  those  which  it  presents  in  its  adult  condi- 
tion. 

Nearly  all  the  causes  of  error,  in  fact,  which  have  suggested  at 
various  times  the  doctrine  of  spontaneous  generation,  have  been 
derived  from  these  two  sources.  First,  the  ready  transportation  of 
eggs  or  germs,  and  their  rapid  hatching  under  favorable  circum- 
stances ;  and  secondly,  the  different  appearances  presented  by  the 
same  animal  at  different  ages,  in  consequence  of  which  the  youthful 
animal  may  be  mistaken,  by  an  ignorant  observer,  for  an  entirely 
different  species.  These  sources  of  error  are,  however,  so  readily 
detected,  as  a  general  rule,  by  scientific  investigation,  that  it  is 
hardly  necessary  to  point  out  the  particular  instances  in  which  they 
exist.  In  fact,  whenever  a  rare  or  comparatively  unknown  animal 
or  plant  has  been  at  any  time  supposed  to  be  produced  by  sponta- 
neous generation,  it  has  only  been  necessary,  for  the  most  part,  to 
investigate  thoroughly  its  habits  and  functions,  to  discover  its  secret 
methods  of  propagation,  and  to  show  that  they  correspond,  in  all 
essential  particulars,  with  the  ordinary  laws  of  reproduction.  The 
limits,  therefore,  within  which  the  doctrine  of  spontaneous  genera- 
tion can  be  applied,  have  been  narrowed  in  precisely  the  same 
degree  that  the  study  of  natural  history  and  comparative  physiology 
has  advanced.  At  present,  indeed,  there  remain  but  two  classes 
of  phenomena  which  are  ever  supposed  to  lend  any  support  to 
the  above  doctrine;  viz.,  the  existence  and  production,  1st,  of  in- 
fusorial animalcules,  and  2d,  of  animal  and  vegetable  parasites. 
We  shall  now  proceed  to  examine  these  two  parts  of  the  subject 
in  succession. 

Infusorial  Animalcules. — If  water,  holding  in  solution  organic 
substances,  be  exposed  to  the  contact  of  the  atmosphere  at  ordinary 
temperatures,  it  is  found  after  a  short  time  to  be  filled  with  swarms 
of  minute  living  organisms,  which  are  visible  only  by  the  micro- 
scope. The  forms  of  these  microscopic  animalcules  are  exceedingly 
varied;  owing  either  to  the  great  number  of  species  in  existence,  or  to 
their  rapid  alteration  during  the  successive  periods  of  their  growth. 
Ehrenberg  has  described  more  than  300  different  varieties  of  them. 


432 


NATUEE    OF    REPEODUCTION. 


Diiferent  kinds  of  Infusoria. 


They  are  generally  provided  with  cilia  attached  to  the  exterior  of 
their  bodies,  and  are,  for  the  most  part,  in  constant  and  rapid  motion 

in  the  flaid  which  they  inha- 
^'g- ^^1-  bit.   Owing  to  their  presence 

in  animal  and  vegetable 
watery  infusions,  they  have 
received  the  name  of  "  infu- 
soria," or  "  infusorial  animal- 
cules." 

Now  these  infusoria  are 
always  produced  under  the 
conditions  which  we  have  de- 
scribed above.  The  animal 
or  vegetable  substance  used 
for  the  infusion  may  be  pre- 
viously baked  or  boiled,  so 
as  to  destroy  all  living  germs 
which  it  might  accidentally 
contain ;  the  water  in  which  it  is  infused  may  be  carefully  distilled, 
and  thus  freed  from  all  similar  contamination;  and  yet  the  infusorial 
animalcules  will  make  their  appearance  at  the  usual  time  and  in  the 
usual  abundance.  It  is  only  requisite  that  the  infusion  be  exposed 
to  a  moderately  elevated  temperature,  and  to  the  access  of  atmo- 
spheric air ;  conditions  which  are  equally  necessary  for  maintaining 
the  life  of  all  animal  and  vegetable  organisms,  whatever  be  the 
source  from  which  they  are  derived.  Under  the  above  circum- 
stances, therefore,  either  the  animalcules  must  have  been  produced 
by  spontaneous  generation  in  the  watery  infusion,  or  their  germs 
must  have  been  introduced  into  it  through  the  medium  of  the  atmo- 
sphere. No  such  introduction  has  ever  been  directly  demonstrated, 
nor  have  even  any  eggs  or  germs  belonging  to  the  infusoria  ever 
been  detected. 

Nevertheless,  there  is  every  probability  that  the  infusoria  are 
produced  from  germs,  and  not  by  spontaneous  generation.  Since 
the  infusoria  themselves  are  microscopic  in  size,  it  is  not  surprising 
that  their  eggs,  which  must  be  smaller  still,  should  have  escaped 
observation.  We  know,  too,  that  in  many  instances  the  minute 
germs  of  animals  or  plants  may  be  wafted  about  in  a  dry  state  by 
the  atmosphere,  until,  by  accidentally  coming  in  contact  with  warmth 
and  moisture,  they  become  developed  and  bring  forth  living  organ- 
isms.    The  eggs  of  the  infusoria,  accordingly,  may  be  easily  raised 


INFUSORIAL    ANIMALCULES.  433 

and  held  suspended  in  the  atmosphere,  under  the  form  of  minute 
dust-like  particles,  ready  to  germinate  and  become  developed  when- 
ever they  are  caught  by  the  surface  of  a  stagnant  pool,  or  of  any 
artificially  prepared  infusion.  In  point  of  fact,  the  atmosphere 
does  really  contain  an  abundance  of  such  dust-like  particles,  even 
when  it  appears  to  be  most  transparent  and  free  from  impurities. 
This  may  be  readily  demonstrated  by  admitting  a  single  beam  of 
sunshine  into  a  darkened  apartment,  when  the  shining  particles  sus- 
pended in  the  atmosphere  become  immediately  visible  in  the  track 
of  the  sunbeam.  Again,  if  a  perfectly  clean  and  polished  mirror 
be  placed  with  its  face  upward  in  a  securely  closed  room,  and  left 
undisturbed  for  several  days,  its  surface  at  the  end  of  that  time  will 
be  found  to  be  dimmed  by  the  settling  upon  it  of  minute  dust, 
deposited  from  the  atmosphere.  There  is  no  reason  therefore  for 
disbelieving  that  the  air  may  always  contain  a  sufficient  number  of 
organic  germs  for  the  production  of  infusorial  animalcules. 

There  is  some  difficulty,  however,  in  obtaining  direct  proof  that  it 
is  through  the  medium  of  the  atmosphere  that  organic  germs  pene- 
trate into  the  watery  infusions.  It  is  true  that  if  such  an  infusion 
be  prepared  from  baked  meat  or  vegetables  and  distilled  water,  and 
afterward  hermetically  sealed,  no  infusoria  are  developed  in  it ;  but 
this  only  shows,  as  we  have  already  intimated,  that  the  free  access 
of  air  is  necessary  to  the  development  of  all  organic  life,  just  as  it  is 
to  the  support  of  animals  and  plants  under  ordinary  conditions  of 
growth  and  reproduction.  Such  a  result,  therefore,  proves  nothing 
with  regard  to  the  external  origin  of  the  infusoria.  In  order  to  be 
conclusive,  such  an  experiment  should  be  so  contrived  that  the 
watery  infusion,  previously  freed  from  all  foreign  contamination, 
should  be  supplied  with  a  free  access  of  atmospheric  air,  while  the 
introduction  of  living  germs  by  this  channel  should  at  the  same  time 
be  rendered  impossible.  An  experiment  of  this  kind  has  in  reality 
been  contrived  and  successfully  carried  out  by  Schultze,  of  Berlin.' 

This  observer  prepared  an  infusion  containing  organic  substances 
in  solution,  and  inclosed  it  in  a  glass  flask  (Fig.  152,  a)  of  such  a 
size,  that  the  infusion  filled  about  one-half  the  entire  capacity  of  the 
vessel.  The  mouth  of  the  flask  was  fitted  with  an  air-tight  stopper 
provided  with  two  holes,  through  which  were  passed  narrow  glass 
tubes  bent  at  right  angles.  To  each  of  these  tubes  was  attached  a 
potass  apparatus  (6,  c),  similar  to  those  used  for  condensing  carbonic 

'  Edinburgh  New  Philosopliical  Journal,  Oct.,  1837. 
28 


434 


NATUEE    OF    REPRODUCTION, 


Schultze's  experiment  on  Sponta- 
XEODs  Generation. — a  Flask  con 
tainiug  watery  infusion.  6.  Potass  ap 
paratus  containing  sulphuric  acid,  c 
Potass  apparatus  containing  caustic  po 
tass. 


acid  in  organic  analyses.     One  of  these  (a)  was  filled  with  concen- 
trated sulphuric  acid,  the  other  {h)  with  a  solution  of  caustic  potass. 

The  flask  with  the  organic  infusion 
having  been  subjected  to  a  boiling 
temperature,  in  order  to  destroy  any 
living  germs  which  it  might  con- 
tain, the  stopper  was  inserted,  and 
the  whole  apparatus  exposed  to  the 
light,  at  the  ordinary  summer  tempera- 
ture. The  connections  of  the  apparatus 
being  perfectly  tight,  no  air  could  pene- 
trate into  the  flask,  except  by  passing 
tlirough  either  the  sulphuric  acid  or 
the  potass;  either  of  which  would  retain 
and  destroy  any  organic  germs  which 
might  be  suspended  in  it.  Every  day 
a  fresh  supply  of  air  was  introduced 
into  the  flask  by  drawing  it  through 
the  tubas  5,  c;  and  in  this  way  the  atmospheric  air  above  the  infu- 
sion was  constantly  renewed,  while  at  the  same  time  the  introduction 
of  living  germs  from  without  was  effectually  prevented. 

Schultze  kept  this  apparatus  under  his  observation,  as  above,  from 
the  last  of  May  till  the  first  of  August;  frequently  examining  the 
edges  of  the  fluid  with  a  lens,  through  the  sides  of  the  glass  jar, 
but  without  ever  detecting  in  it  any  traces  of  living  organisms.  At 
the  end  of  that  period  the  flask  was  opened,  and  the  fluid  which  it 
contained  subjected  to  direct  examination,  equally  without  result. 
It  was  then  exposed,  in  the  same  vessel  and  in  the  same  situation 
as  before,  to  the  free  access  of  the  atmosphere,  and  at  the  end  of 
two  or  three  days  it  was  found  to  be  swarming  with  infusoria. 

It  is  plain,  therefore,  that  the  infusoria  cannot  be  regarded  as 
produced  by  spontaneous  generation,  but  must  be  considered  as 
originating  in  the  usual  manner  from  germs;  since  they  do  not 
make  their  appearance  in  the  watery  infusion,  when  the  accidental 
introduction  of  germs  from  without  has  been  effectually  prevented. 


Animal  and  Vegetable  Parasites. — This  very  remarkable 
group  of  organized  bodies  is  distinguished  by  the  fact  that  they 
live  either  upon  the  surface  or  in  the  interior  of  other  animal  or 
vegetable  organisms.  Thus,  the  mistletoe  fixes  itself  on  the  branches 
of  aged  trees;  the  Oldium  albicans  vegetates  upon  the  mucous  sur- 


ANIMAL    AND    VEGETABLE    PARASITES.  435 

faces  of  the  moiilh  and  pharynx ;  the  Botrytls  Bassiana  attacks  the 
body  of  the  silkworm,  and  plants  itself  in  its  tissues;  while  many 
species  of  trematoid  icorms  live  attached  to  the  gills  of  fish  and  of 
water-lizards. 

These  parasites  are  usually  nourished  by  the  fluids  of  the  animal 
whose  body  they  inhabit.  Each  particular  species  of  parasite  is 
found  to  inhabit  the  body  of  a  particular  species  of  animal,  and  is 
not  found  elsewhere.  They  are  met  with,  moreover,  as  a  general 
rule,  only  in  particular  organs,  or  even  in  particular  parts  of  a  single 
organ.  Thus  the  Tricocephalus  dispar  is  found  only  in  the  caecum  ; 
the  Strongylus  gigas  in  the  kidney;  the  Distoma  hepaticum  in  the 
biliary  passages.  The  Distoma  variegatum  is  found  only  in  the 
lungs  of  the  green  frog,  the  Distoma  cylindraceura  in  those  of  the 
brown.  The  Teenia  solium  is  found  in  the  intestine  of  the  human 
subject  in  certain  parts  of  Europe,  while  the  Taenia  lata  occurs  ex- 
clusively in  others.  It  appears,  therefore,  as  though  some  local 
combination  of  conditions  were  necessary  to  the  production  of  these 
parasites ;  and  they  have  been  supposed,  accordingly,  to  originate 
by  spontaneous  generation  in  the  localities  where  they  are  exclu- 
sively known  to  exist. 

A  little  consideration  will  "show,  however,  that  the  above  condi- 
tions are  not,  properly  speaking,  necessary  or  sufficient  for  the 
production^  but  only  for  the  development  of  these  parasites.  All  the 
parasites  mentioned  above  reproduce  their  species  by  generation. 
They  have  male  and  female  organs,  and  produce  fertile  eggs,  often 
in  great  abundance.  The  eggs  contained  in  a  single  female  Ascuris 
are  to  be  counted  by  thousands;  and  in  a  tapeworm,  it  is  said,  even 
by  millions.  Now  these  eggs,  in  order  that  they  may  be  hatched 
and  produce  new  individuals,  require  certain  special  conditions 
which  are  favorable  for  their  development;  in  the  same  manner 
as  the  seeds  of  plants  require,  for  their  germination  and  growth,  a 
certain  kind  of  soil  and  a  certain  supply  of  warmth  and  moisture. 
It  is  accordingly  no  more  surprising  that  the  Ascaris  vermicularix 
should  inhabit  the  rectum,  and  the  Ascaris  lumbricoides  the  ileum, 
than  that  the  Lobelia  inflata  should  grow  only  in  dry  pastures,  and 
the  Lobelia  cardinalis  by  the  side  of  running  brooks.  The  lichens 
flourish  on  the  exposed  surfaces  of  rocks  and  stone  walls ;  while 
the  fungi  vegetate  in  darkness  and  moisture,  on  the  decaying  trunks 
of  dead  trees.  Yet  no  one  imagines  these  vegetables  to  be  spon- 
taneously generated  from  the  soil  which  they  inhabit.  The  truth  is 
simply  this,  that  if  the  animal  or  vegetable  germ  bs  deposited  in  a 


436  NATURE    OF    KEPRODUCTION. 

locality  which  affords  the  requisite  conditions  for  its  development, 
it  becomes  developed;  otherwise  not.  Each  female  Ascaris  pro- 
duces, as  we  have  stated  above,  many  thousands  of  ova.  Now, 
though  the  chances  are  very  great  against  any  particular  one  of 
these  ova  being  accidentally  transported  into  the  intestinal  canal  of 
another  individual,  it  is  easy  to  see  that  there  are  many  causes  in 
operation  by  which  some  of  them  might  be  so  transported.  By  far 
the  greater  number  undoubtedly  perish,  from  not  meeting  with  the 
conditions  necessary  for  their  development.  One  in  a  thousand,  or 
perhaps  one  in  a  million,  is  accidentally  introduced  into  the  body 
of  another  individual,  and  consequently  becomes  developed  there 
into  a  perfect  Ascaris. 

The  circumstance,  therefore,  that  particular  parasites  are  confined 
to  particular  localities,  presents  no  greater  difficulty  as  to  their 
mode  of  reproduction,  than  the  same  fact  regarding  other  animal 
and  vegetable  organisms. 

Neither  is  there  any  difficulty  in  accounting  for  the  introduction 
of  parasitic  germs  into  the  interior  of  the  body.  The  air  and  the 
food  offer  a  ready  means  of  entrance  into  the  respiratory  and 
digestive  passages;  and,  a  parasite  once  introduced  into  the  intestine, 
there  is  no  difficulty  in  accounting  for  its  presence  in  any  of  the 
ducts  leading  from  or  opening  into  the  alimentary  canal.  Some 
parasites  are  known  to  insinuate  themselves  directly  underneath 
the  surface  of  the  skin ;  as  the  Pulex  penetrans  or  "  chiggo"  of 
South  America,  and  the  Ixodes  Americana  or  "tick."  Others, 
like  the  (Estrus  bovis,  penetrate  the  integument  for  the  purpose  of 
depositing  their  eggs  in  the  subcutaneous  areolar  tissue.  Some 
may  even  gain  an  entrance  into  the  bloodvessels,  and  circulate  in 
this  way  all  over  the  body.  Thus  the  Filaria  rubella  is  found  alive 
in  the  bloodvessels  of  the  frog;  and  a  species  of  Spiroptera  in  those 
of  the  dog.  It  is  easy  to  see,  therefore,  how,  by  such  means,  para- 
sitic germs  may  be  conveyed  to  any  part  of  the  body ;  and  may 
even  be  deposited,  by  accidental  arrest  of  the  circulation,  in  the 
substance  of  the  solid  organs. 

The  most  serious  difficulty,  however,  in  the  way  of  accounting 
for  the  production  of  parasitic  organisms,  was  that  presented  by  the 
existence  of  a  class  known  as  the  encysted  or  sexless  entpzoa.  These 
parasites  for  the  most  part  occupy  the  interior  of  the  solid  organs 
and  tissues,  into  which  they  could  not  have  gained  access  by  the 
mucous  canals.  Thus  the  Coenurus  cerebralis  is  found  imbedded 
in  the  substance  of  the  brain,  the  Trichina  spiralis  between  the 


ANIMAL    AND    VEGETABLE    PARASITES. 


437 


Trichina  Spiralis;  from  rectus  femoris  mus- 
cle of  human  subject.     Magnified  57  diameters.  i 


fibres  of  the  voluntary  muscles,  and  the  Cysticercus  cellulosse  in  the 
areolar  tissue  of  various  parts  of  the  body.  They  are  also  distin- 
guished from  all  other  parasites  by  two  peculiar  characters.  First, 
they  are  inclosed  in  a  distinct  cyst,  with  which  they  have  no  organic 
connection  and  from  which  they  may  be  readily  separated ;  and  se- 
condlj'-,  they  have  no  genera- 
tive organs,  nor  is  there  any  Fig.  153. 
apparent  difference  between 
the  sexes.  The  Trichina  spi- 
ralis, for  example  (Fig.  153), 
is  inclosed  in  an  ovoid  or 
spindle-shaped  cyst,  swollen 
in  the  middle  and  tapering  at 
each  extremity,  with  a  round- 
ed cavity  in  its  central  por- 
tion, in  which  the  worm  lies 

coiled  up  in  a  spiral  form.     The  worm  itself  has  neither  testicles 
nor  ovaries,  nor  does  it  present  any  trace  of  a  sexual  organization. 

Now  we  have  seen  that  it  is  easy  to  account  for  the  conveyance 
of  these  or  any  other  parasites  into  the  interior  of  vascular  organs 
and  tissues;  the  eggs  from  which  they  are  produced  being  trans- 
ported by  the  bloodvessels  to  any  part  of  the  body,  and  there 
retained  by  a  lacal  arrest  of  the  capillary  circulation.  In  the  case 
of  the  encysted  entozoa,  however,  we  have  a  much  greater  diffi- 
culty; since  these  parasites  are  entirely  without  sexual  organs  or 
generative  apparatus  of  any  sort,  nor  have  they  ever  been  dis- 
covered in  the  act  of  producing  eggs,  or  of  developing  in  any 
manner  a  progeny  similar  to  themselves.  It  appears,  accordingly, 
difficult  to  understand  how  animals,  which  are  without  a  sexual 
apparatus,  should  have  been  produced  by  sexual  generation.  As 
it  is  certain  that  they  can  have  no  progeny,  it  would  seem  equally 
evident  that  they  must  have  been  produced  without  a  parentage. 

This  difficulty,  however,  serious  as  it  at  first  appears,  is  susceptible 
of  a  very  simple  explanation.  The  case  is  in  many  respects  analogous 
to  that  of  the  maggots,  hatched  from  the  eggs  of  flies  in  putrefying 
meat.  These  maggots  are  also  without  sexual  organs ;  for  they 
are  still  imperfectly  developed,  and  in  a  kind  of  embryonic  condi- 
tion. It  is  only  after  their  metamorphosis  into  perfect  insects,  that 
generative  organs  are  developed  and  a  distinction  between  the 
sexes  manifests  itself.  This  is,  indeed,  more  or  less  the  case  with 
all  animals  and  with  all  vegetables.     The  blossom,  which  is  the 


438 


NATURE    OF    REPRODUCTION. 


Fig.  154. 


sexual  apparatus  of  the  plant,  does  not  appear,  as  a  general  rule, 
until  the  growth  of  the  vegetable  has  continued  for  a  certain  time, 
and  it  has  acquired  a  certain  age  and  strength.  Even  in  the  human 
subject  the  sexual  organs,  though  present  at  birth,  are  still  very 
imperfectly  developed  as  to  size,  and  altogether  inactive  in  func- 
tion. It  is  only  later  that  these  organs  acquire  their  full  growth, 
and  the  sexual  characters  become  complete.  In  very  many  of  the 
lower  animals  the  sexual  organs  are  entirely  absent  at  birth,  and 
appear  only  at  a  later  period  of  development. 

Now  the  encysted  or  sexless  entozoa  are  simply  the  undeveloped 
young  of  other  parasites  which  propagate  by  sexual  generation ; 
the  detached  membrane  in  which  they  are  enveloped  being  either 
the  external  membrane  of  the  egg,  not  yet  ruptured,  or  else  an 
adventitious  cyst  formed  round  the  parasitic  embryo.  These 
embryos  have  come,  either  accidentally,  or  in  the  natural  course  of 
their  migrations,  to  a  situation  which  is  not 
suitable  for  their  complete  development.  Their 
development  is  accordingly  arrested  before  it 
arrives  at  maturity ;  and  the  parasite  never 
reaches  the  adult  condition,  until  removed  from 
the  situation  in  which  it  has  been  placed,  and 
transported  to  a  more  favorable  locality. 

The  above  explanation  has  been  demon- 
strated to  be  the  true  one,  more  particularly 
with  regard  to  the  Teenia,  or  tapeworm,  and 
several  varieties  of  Cysticercus.  The  Taenia 
(Fig.  154)  is  a  parasite  of  which  different  species 
are  found  in  the  intestine  of  the  human  subject, 
the  dog,  cat,  fox,  and  other  of  the  lower  animals. 
Its  upper  extremity,  termed  the  "head,"  con- 
sists of  a  nearly  globular  mass,  presenting  upon 
its  lateral  surfaces  a  set  of  four  muscular  disks, 
or  "suckers,"  and  terminating  anteriorly  in  a 
conical  projection  which  is  provided  with  a 
crown  of  curved  processes  or  hooks,  by  which 
the  parasite  attaches  itself  to  the  intestinal 
mucous  membrane.  To  this  "head"  succeeds 
a  slender  ribbon-shaped  neck,  which  is  at  first 
smooth,  but  which  soon  becomes  transversely 
wrinkled,  and  afterward  divided  into  distinct 
rectangular  pieces  or  "articulations."     These 


ANIMAL    AND    VEGETABLE    PARASITES. 


439 


articulations  multiply  by  a  process  of  successive  growth  or  bud- 
ding, from  the  wrinkled  portion  of  the  neck;  and  are  constantly 
removed  farther  and  farther  from  their  point  of  origin  by  new 
ones  formed  behind  them.  As  they  gradually  descend,  by  the 
process  of  growth,  farther  down  the  body  of  the  tapeworm,  they 
become  larger  &nd  begin  to  exhibit  a  sexual  apparatus,  developed 
in  their  interior.  In  each  fully  formed  articulation  there  are  con- 
tained both  male  and  female  organs  of  generation  ;  and  the  mature 
eggs,  which  are  produced  in  great  numbers,  are  thrown  off  to- 
gether with  the  articulation  itself  from  the  lower  extremity  of  the 
tapeworm.  Since  the  articulations  are  successively  produced,  as 
we  have  mentioned  above,  by  budding  from  the  neck  and  the  back 
part  of  the  head,  the  parasite  cannot  be  effectually  dislodged  by 
taking  away  any  portion  of  the  body,  however  large ;  since  it  is 
subsequently  reproduced  from  the  head,  and  continues  its  growth 
as  before.  But  if  the  head  itself  be  removed  from  the  intestine,  no 
further  reproduction  of  the  articulations  can  take  place. 

The  Cysticercus  is  an  encysted  parasite,  different  varieties  of  which 
are  found  in  the  liver,  the  peritoneum,  and  the  meshes  of  the  areolar 
tissue  in  various  parts  of  the  body.  It  consists  (Fig.  155),  first,  of 
a  globular  sac,  or  cyst  (a),  which  is  not  adherent  to  the  tissues  of 
the  organ  in  which  the  parasite  is  found,  but  may  be  easily  sepa- 
rated from  them.     In  its  interior  is  found  another  sac  (6),  lying 


Fig.  155. 


Fig.  156. 


Cysticercus. — a.  External  cyst.  6.  In- 
tornal  sac,  coataining  fluid  c.  Narrow  canal, 
furmed  by  involution  of  walls  of  sac,  at  the 
bottom  of  which  is  the  head  of  the  tasuia. 


Ctsticekcus,   unfolded. 


loose  in  the  cavity  of  the  former,  and  filled  with  a  serous  fluid. 
This  second  sac  presents,  at  one  point  upon  its  surface,  a  puckered 
depression,  leading  into  a  long,  narrow  canal  (c).  This  canal,  which 
is  formed  by  an  involution  of  the  walls  of  the  second  sac,  presents 
at  its  bottom  a  small  globular  mass,  like  the  head  of  the  T^nia, 


440  NATURE    OF    REPRODUCTION. 

provided  with  suckers  and  hooks,  and  supported  upon  a  short 
slender  neck.  If  the  outer  investing  sac  be  removed,  the  narrow 
canal  just  described  may  be  everted  by  careful  manipulation,  and 
the  parasite  will  then  appear  as  in  Fig.  156,  with  the  head  and  neck 
resembling  those  of  a  Taenia,  but  terminating  behind  in  a  dropsical 
sac-like  swelling,  instead  of  the  chain  of  articulations  which  are 
characteristic  of  the  fully  formed  tapeworm. 

Now  it  has  been  shown,  by  the  experiments  of  Kiichenmeister, 
Siebold,  and  others,  that  the  Cysticercus  is  only  the  imperfectly 
developed  embryo,  or  young  of  the  T^nia.  If  the  mature  egg  of 
the  Taenia  be  conveyed  into  the  intestine  of  another  animal  of  simi- 
lar species,  it  hatches ;  and  the  globular  mass  or  head  which  is  pro- 
duced from  it,  after  fixing  itself  to  the  mucous  membrane,  produces 
the  long,  tape-like  series  of  articulations,  by  the  process  of  succes- 
sive growth,  or  budding,  already  described.  But  if  the  same  egg 
find  its  way  accidentally  into  the  cellular  tissue,  the  peritoneum,  or 
the  liver,  situations  which  are  unnatural  to  it  and  unfavorable  to 
its  development,  it  is  not  hatched.  The  head  remains  retracted 
within  the  neck,  as  in  Fig.  155,  and  still  covered  with  the  external 
membrane  of  the  egg,  or  investing  cyst. 

Prof.  Siebold  found  the  head  of  the  Cysticercus  fasciolaris,  met 
with  in  the  liver  of  rats  and  mice,  presenting  so  close  a  resem- 
blance to  the  Taenia  crassicollis,  inhabiting  the  intestine  of  the  cat, 
that  he  was  led  to  believe  the  two  parasites  to  be  identical.  This 
identity  was,  in  fact,  proved  by  the  experiments  of  Kiichenmeister ; 
and  Siebold  afterward  demonstrated'  the  same  relation  to  exist 
between  the  Cysticercus  pisiformis,  found  in  the  peritoneum  of  rab- 
bits, and  the  Taenia  serrata,  from  the  intestine  of  the  dog.  This 
experimenter  succeeded  in  administering  to  dogs  a  quantity  of  the 
cysticerci,  fresh  from  the  body  of  the  rabbit,  mixed  with  milk ;  and 
on  killing  the  dogs,  at  various  periods  after  the  meal,  from  three 
hours  to  eight  weeks,  he  found  the  cysticerci  in  various  stages  of 
development  in  the  intestine,  and  finally  converted  into  the  full 
grown  Taenia,  with  complete  articulations  and  mature  eggs. 

Dr.  Kiichenmeister*  has  also  performed  the  same  experiment,  with 
success,  on  the  human  subject.  A  number  of  cysticerci  were  admi- 
nistered to  a  criminal,  at  difi'erent  periods  before  his  execution, 

'  In  Buffalo  Medical  Journal,  Feb.  1853 ;  also  in  Siebold  on  Tape  and  Cystic 
Worms,  Sydenham  translation  :  London,  1857,  p.  59." 

^  On  Animal  and  Vegetable  Parasites,  Sydenham  Translation :  London,  1857, 
p.  115. 


ANIMAL    AND    VEGETABLE    PARASITES,  441 

varying  from  12  to  72  hours;  and  upon  post-mortem  examination 
of  the  body,  no  less  than  ten  young  tasniee  were  found  in  the 
intestine,  four  of  which  could  be  distinctly  recognized  as  specimens 
of  Taenia  solium. 

Finally,  both  Leuckart  and  Kiichenmeister'  have  shown,  on  the 
other  hand,  that  the  eggs  of  Taenia  solium,  introduced  into  the  body 
of  the  pig,  will  give  rise  to  the  development  of  Cysticercus  cellulosge; 
thus  demonstrating  that  the  two  kinds  of  parasites  are  identical  in 
their  nature,  and  differ  only  in  the  manner  and  degree  of  their 
development. 

There  remains,  accordingly,  no  good  reason  for  believing  that 
even  the  encysted  parasites  are  produced  by  spontaneous  genera- 
tion. Whatever  obscurity  may  hang  round  the  origin  or  reproduc- 
tion of  any  class  or  species  of  animals,  the  direct  investigations  of 
the  physiologist  always  tend  to  show  that  they  do  not^  in  reality, 
form  any  exception  to  the  general  law  in  this  respect;  and  the  only 
opinion  which  is  admissible,  from  the  facts  at  present  within  our 
knowledge,  is  that  organized  beings^  animal  and  vegetable^  ivherever  they 
may  be  found,  are  always  the  progeny  of  previously  existing  parents. 

'  Op  cit.,  p.  120. 


442 


SEXUAL    GENEEATION. 


CHAPTER    II. 

ON  SEXUAL  GENERATION,  AND  THE  MODE  OF  ITS 
ACCOMPLISHMENT. 


Fig.  157. 


The  function  of  generation  is  performed  by  means  of  two  sets  of 
organs,  each  of  which  gives  origin  to  a  peculiar  product,  capable  of 
uniting  with  the  other  so  as  to  produce  a  new  individual.     These 

two  sets  of  organs,  belonging  to  the 
two  different  sexes,  are  called  the  male 
and  female  organs  of  generation.  The 
female  organs  produce  a  globular  body 
called  the  germ^  or  egg^  which  is  capable 
of  being  developed  into  the  body  of 
the  young  animal  or  plant ;  the  male 
organs  produce  a  substance  which  is 
necessary  to  fecundate  the  germ,  and 
enable  it  to  go  through  with  its  natural 
growth  and  development. 

Such  are  the  only  essential  and  uni- 
versal characters  of  the  organs  of  gene- 
ration. These  organs,  however,  exhibit 
various  additions  and  modifications  in 
different  classes  of  organized  beings, 
while  they  show  throughout  the  same 
fundamental  and  essential  characters. 

In  the  flowering  plants,  for  example, 
the  blossom,  which  is  the  generative 
apparatus  (Fig.  157),  consists  first  of  a 
female  organ  containing  the  germ  (a),  situated  usually  upon  the 
highest  part  of  the  leaf-bearing  stalk.  This  is  surmounted  by  a 
nearly  straight  column,  termed  the  pistil  (6),  dilated  at  its  summit 
into  a  globular  expansion,  and  occupying  the  centre  of  the  flower. 
Around  it  are  arranged  several  slender  filaments,  or  stamens,  bear- 
ing upon  their  extremities  the  male  organs,  or  anthers  (c,  c).     The 


Blossom  op  Convolvuhts 
PtruPDREUS.  (Morniug  glory.) — a. 
Gorni.  6.  Pistil,  c,  c.  Stamen.s,  witli 
anthers,     d.  Corolla      e.  Calyx 


SEXUAL    GENERATION. 


443 


whole  is  surrounded  by  a  circle  or  crown  of  delicate  and  brilliantly 
colored  leaves,  termed  the  corolla  {d),  which  is  frequently  provided 
with  a  smaller  sheath  of  green  leaves  outside,  called  the  calyx  (e). 
The  anthers,  when  arrived  at  maturity,  discharge  a  fine  organic 
dust,  called  the  pollen,  the  granules  of  which  are  caught  upon  the 
extremity  of  the  pistil,  and  then  penetrate  downward  through  its 
tissues,  until  they  reach  its  lower  extremity  and  come  in  contact 
with  the  germ.  The  germ  thus  fecundated,  the  process  of  genera- 
tion is  accomplished.  The  pistil,  anthers,  and  corolla  wither  and 
fall  off,  while  the  germ  increases  rapidly  in  size,  and  changes  in 
form  and  texture,  until  it  ripens  into  the  mature  fruit  or  seed.  It 
is  then  ready  to  be  separated  from  the  parent  stem ;  and,  if  placed 
in  the  proper  soil,  will  germinate  and  at  last  produce  a  new  plant 
similar  to  the  old. 

In  the  above  instance,  the  male  and  female  organs  are  both 
situated  upon  the  same  flower;  as  in  the  lily,  the  violet,  the  con- 
volvulus, &c.  In  other  cases,  there  are  separate  male  and  female 
flowers  upon  the  same  plant,  of  which  the  male  flowers  produce 
only  the  pollen,  the  female,  the 

germ  and  fruit.     In  others  still,  Fig-  158. 

the  male  and  female  flowers  are 
situated  upon  different  plants, 
which  otherwise  resemble  each 
other,  as  in  the  willow,  poplar, 
and  hemp. 

In  animals,  the  female  organs 
of  generation  are  called  ovaries^ 
since  it  is  in  them  that  the  egg, 
or  "ovum,"  is  produced.  The 
male  organs  are  the  testicles^ 
which  give  origin  to  the  fecun- 
dating product,  or  "seminal 
fluid,"  by  which  the  egg  is  fer- 
tilized. We  have  already  men- 
tioned above  that  in  the  articula- 
tions of  the  tapeworm  the  ovaries 
and.  testicles  are  developed  to- 
gether.  (Fig.  158.)     The   ovary 

(a,  a,  a)  is  a  series  of  branching  follicles  terminating  in  rounded 
extremities,  and  communicating  with  each  other  by  a  central  canal. 
The  testicle  {h)  is  a  narrow,  convoluted   tube,  very  much  folded 


\s. 

,             ^^>^  1  " 

fevl. 

^ 

■^^•s           I 

'■^T^ 

-^":3  \ 

=.-•"  = 

-  ^-,   \ 

@- 

'    \ 

'^^^rrroiri^ 

_     \ 

Single  A  h t i c u  i,  a t i o x  of  T .b n  i  a 
Crassicoi, I, IS,  from  small  intestino  of  cat. — 
a,  a,  a.  Ovary  filled  with  eggs.  b.  Testicle,  c. 
Geaital  orifice. 


444  SEXUAL    GENERATION. 

upon  itself,  which  opens  by  an  external  orifice  (c)  upon  the  lateral 
border  of  the  articulation,  about  midway  between  its  two  ex- 
tremities. The  spermatic  fluid  produced  in  the  testicle  is  intro- 
duced into  the  female  generative  passage,  which  opens  at  the  same 
spot,  and,  penetrating  deeply  into  the  interior,  comes  in  contact 
with  the  eggs,  which  are  thereby  fecundated  and  rendered  fertile. 
The  fertile  eggs  are  afterward  set  free  by  the  rupture  or  decay  of 
the  articulation,  and  a  vast  number  of  young  produced  by  their 
development. 

In  snails,  also,  and  in  some  other  of  the  lower  animals,  the  ovaries 
and  testicles  are  both  present  in  the  same  individual ;  so  that  these 
animals  are  sometimes  said  to  be  "  hermaphrodite,"  or  of  double 
sex.  In  realit}^,  however,  it  appears  that  the  male  and  female 
organs  do  not  come  to  maturity  at  the  same  time;  but  the  ovaries 
•  are  first  developed  and  perform  their  function,  after  which  the  tes- 
ticles come  into  activity  in  their  turn.  The  same  individual,  there- 
fore, is  not  both  male  and  female  at  any  one  time ;  but  is  first 
female  and  afterward  male,  exercising  the  two  generative  functions 
at  different  ages. 

In  all  the  higher  animals,  however,  the  two  sets  of  generative 
organs  are  located  in  separate  individuals;  and  the  species  is 
consequently  divided  into  two  sexes,  male  and  female.  All  that 
is  absolutely  requisite  to  constitute  the  two  sexes  is  the  existence 
of  testicles  in  the  one,  and  of  ovaries  in  the  other.  Beside  these, 
however,  there  are,  in  most  instances,  certain  secondary  or  acces- 
sory organs  of  generation,  which  assist  more  or  less  in  the  accom- 
plishment of  the  process,  and  which  occasion  a  greater  difference 
in  tlie  anatomy  of  the  two  sexes.  Suet  are  the  uterus  and  mam- 
mary glands  of  the  female,  the  vesiculse  seminales  and  prostate 
of  the  male.  The  female  naturally  having  the  immediate  care  of 
the  young  after  birth,  and  the  male  being  occupied  in  providing 
food  and  protection  for  both,  there  are  also  corresponding  differ- 
ences in  the  general  structure  of  the  body,  which  affect  the  whole 
external  appearance  of  the  two  sexes,  and  which  even  show  them- 
selves in  their  mental  and  moral,  as  well  as  in  their  physical 
characteristics.  In  some  cases  this  difference  is  so  excessive  that 
the  male  and  female  would  never  be  recognized  as  belonging  to  the 
same  species,  unless  they  were  seen  in  company  with  each  other. 
Not  to  mention  some  extreme  instances  of  this  among  insects  and 
other  invertebrate  animals,  it  will  be  sufficient  to  refer  to  the  well 
known  examples  of  the  cock  and  the  hen,  the  lion  and  lioness,  the 


SEXUAL    GENERATION".  445 

buck  and  the  doe.  In  the  human  species,  also,  the  distinction 
between  the  sexes  shows  itself  in  the  mental  constitution,  the  dis- 
position, habits,  and  pursuits,  as  well  as  in  the  general  conforma- 
tion of  the  body,  and  the  peculiarities  of  external  appearance. 

We  shall  now  study  more  fully  the  character  of  the  male  and 
female  organs  of  generation,  together  with  their  products,  and  the 
manner  in  which  these  are  discharged  from  the  body,  and  brought 
into  relation  with  each  other. 


446 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


CHAPTER  III. 

ON  THE  EGG,  AND  THE  FEMALE  ORGANS  OF 
GENERATION. 


The  egg  is  a  globular  body  which  varies  considerably  in  size  in 
different  classes  of  animals,  according  to  the  peculiar  conditions 
under  which  its  development  is  to  take  place.  In  the  frog  it  mea- 
sures yig  of  an  inch,  in  the  lamprey  g'g,  in  quadrupeds  and  in  the 
human  species  y|(^.  It  consists,  first,  of  a  membranous  external 
sac  or  envelope,  the  vitelline  membrane;  and  secondly,  of  a  spherical 
mass  inclosed  in  its  interior,  called  the  vitellus. 

The  vitelline  membrane  in  birds  and  reptiles  is  very  thin,  measur- 
ing often  not  more  than  tsoct)  of  an  inch  in  thickness,  and  is  at  the 

same  time  of  a  somewhat  fibrous  texture, 
^^g-  ^^^-  In   man  and  the   higher  animals,  on  the 

contrary,  it  is  perfectly  smooth,  structure- 
less and  transparent,  and  is  about  ^^^-q  of 
an  inch  in  thickness.  Notwithstanding 
its  delicate  and  transparent  appearance,  it 
has  a  considerable  degree  of  resistance 
and  elasticity.  The  egg  of  the  human 
subject,  for  example,  may  be  perceptibly 
flattened  out  under  the  microscope  by 
pressing  with  the  point  of  a  needle  upon 
the  slip  of  glass  which  covers  it;  but  it 
still  remains  unbroken,  and  when  the 
pressure  is  removed,  readily  resumes  its  globular  form.  When  the 
egg  is  somewhat  flattened  under  the  microscope  in  this  way,  by 
pressure  of  the  glass  slip,  the  apparent  thickness  of  the  vitelline 
membrane  is  increased,  and  it  then  appears  (Fig.  159)  as  a  rather 
wide,  colorless,  and  pellucid  border  or  zone,  surrounding  the  granu- 
lar and  opaque  vitellus.  Owing  to  this  appearance,  it  has  some- 
times received  the  name  of  the  "zona  pellucida."  The  name  of 
vitelline  membrane,  however,  is  the  one  more  generally  adopted, 
and  is  also  the  more  appropriate  of  the  two. 


Human  Ovum,  magnified  S.3 
diameters,  a.  Virelline  mpmbrane. 
h.  Vitellus.  c.  Genniuative  vesicle. 
d.  Germinative  spot. 


EGG  AND  FEMALE  ORGANS  OF  GENERATION.    447 

The  vilellus  {h),  is  a  globular,  semi-solid  mass,  contained  within 
the  vitelline  membrane.  It  consists  of  a  colorless  albuminoid  sub- 
stance, with  an  abundance  of  minute  molecules  and  oleaginous 
granules  scattered  through  it.  These  minute  oleaginous  masses 
give  to  the  vitellus  a  partially  opaque  and  granular  aspect  under 
the  microscope.  Imbedded  in  the  vitellus,  usually  near  its  surface 
and  almost  immediately  beneath  the  vitelline  membrane,  there  is  a 
clear,  colorless,  transparent  vesicle  (c)  of  a  rounded  form,  known 
as  the  germinative  vesicle.  In  the  egg  of  the  human  subject  and  of 
the  quadrupeds,  this  vesicle  measures  ggo  to  g  J^  of  an  inch  in 
diameter.  It  presents  upon  its  surface  a 
dark  spot,  like  a  nucleus  {d),  which  is  known  ^'S*  ^'^^' 

by  the  name  of  the  germinative  spot.  The 
germinative  vesicle,  with  its  nucleus-like 
spot,  is  often  partially  concealed  by  the 
granules  of  the  vitellus  by  which  it  is  sur- 
rounded, but  it  may  always  be  discovered 
by  careful  examination. 

If  the  egg  be  ruptured  by  excessive  pres-       human  ovum,  luptmed  ly 

,  ,  .  ,  .      ,,  .  pressure;    showing  the  vitellus 

sure    under    the,   microscope,    the  vitellus     is       partially  expelled,  the  germlnu- 

seen  to  have  a  gelatinous  consistency.     It     '*'<^  ''^^'c'e  at «,  and  the  smooth 

.  fracture   of    the   vitelline   mem- 

is    gradually  expelled    from  the  vitelline     brane. 
cavity,  but  still  retains  the  granules  and  oil 

globules  entangled  in  its  substance.  (Fig.  160.)  The  edges  of  the 
fractured  vitelline  membrane,  under  these  circumstances,  present  a 
smooth  and  nearly  straight  outline,  without  any  appearance  of 
laceration  or  of  a  fibrous  structure.  The  membrane  is,  to  all  ap- 
pearance, perfectly  homogeneous. 

The  most  essential  constituent  of  the  egg  is  the  vitellus.  It  is 
from  the  vitellus  that  the  body  of  the  embryo  will  afterward  be 
formed,  and  the  organs  of  the  new  individual  developed.  The 
vitelline  membrane  is  merely  a  protective  inclosure,  intended  to 
jirotect  the  vitellus  from  injury,  and  enable  it  to  retain  its  figure 
during  the  ea:rly  periods  of  development. 

The  egg,  as  above  described,  consists  therefore  of  a  simple 
vitellus  of  minute  size,  and  a  vitelline  membrane  inclosing  it.  It 
is  such  an  egg  which  is  found  in  the  human  subject,  the  quadru- 
peds, most  aquatic  reptiles,  very  many  fish,  and  some  invertebrate 
jinimals.  In  nearly  all  those  species,  in  fact,  where  the  fecundated 
eggs  are  deposited  and  hatched  in  the  water,  as  well  as  those  in 
which  they  are  retained  in  the  body  of  the  female  until  the  develop- 


448    EGa  AND  FEMALE  ORGANS  OF  GENERATION. 

merit  of  the  young  is  completed,  such  an  egg  as  above  described  is 
sufficient  for  the  formation  of  the  embryo;  since  during  its  develop- 
ment it  can  absorb  freely,  either  from  the  water  in  which  it  floats, 
or  from  the  mucous  membrane  of  the  female  generative  organs,  the 
requisite  supply  of  nutritious  fluids.  But  in  birds  and  in  the 
terrestrial  reptiles,  such  as  lizards,  tortoises,  &c.,  where  the  eggs 
are  expelled  from  the  body  of  the  female  at  an  early  period,  and 
incubated  on  land,  there  is  no  external  source  of  nutrition,  to  pro- 
vide for  the  support  of  the  young  animal  during  its  development. 
In  these  instances  accordingly  the  vitellus,  or  "yolk,"  as  it  is  called, 
is  of  very  large  size;  and  the  bulk  of  the  egg  is  still  further  in- 
creased by  the  addition,  within  the  female  generative  passages,  of 
layers  of  albumen  and  various  external  fibrous  and  calcareous 
envelopes.  The  essential  constituents  of  the  egg,  however,  still 
remain  the  same  in  character,  and  the  process  of  embryonic  develop- 
ment follows  the  same  general  laws  as  in  other  cases. 

The  eggs  are  produced  in  the  interior  of  certain  organs,  situated 
in  the  abdominal  cavity,  called  the  ovaries.  These  organs  consist 
of  a  number  of  globular  sacs,  or  follicles,  known  as  the  "Graafian 
follicles,"  each  one  of  which  contains  a  single  egg.  The  follicles 
are  connected  with  each  other  by  a  quantity  of  vascular  areolar 
tissue,  which  binds  them  together  into  a  well  defined  and  consistent 
mass,  covered  upon  its  exterior  by  a  layer  of  peritoneum.  The 
egg  has  sometimes  been  spoken  of  as  a  "  product,"  or  even  as  a 
"  secretion"  of  the  ovary.  Nothing  can  be  more  inappropriate, 
however,  than  to  compare  the  egg  with  a  secretion,  or  to  regard  the 
ovary  as  in  any  respect  resembling  a  glandular  organ.  The  egg  is 
simply  an  organized  body,  growing  in  the  ovary  like  a  tooth  in  its 
follicle,  and  forming  a  constituent  part  of  the  body  of  the  female. 
It  is  destined  to  be  finally  separated  from  its  attachments  and  thrown 
off;  but  until  that  time,  it  is,  properly  speaking,  a  part  of  the 
ovarian  texture,  and  is  nourished  like  any  other  portion  of  the 
female  organism. 

The  ovaries,  accordingly,  since  they  are  directly  concerned  in 
the  production  of  the  eggs,  are  to  be  regarded  as  the  essential 
parts  of  the  female  generative  apparatus.  Beside  them,  however, 
there  are  usually  present  certain  other  organs,  which  play  a  secon- 
dary or  accessory  part  in  the  process  of  generation.  The  most 
important  of  these  accessory  organs  are  two  symmetrical  tubes,  or 
oviducts,  which  are  destined  to  receive  the  eggs  at  their  internal 
extremity  and  convey  them  to  the  external  generative  orifice.     The 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


449 


mucous  membrane  lining  the  oviducts  is  also  intended  to  supply 
certain  secretions  during  the  passage  of  the  egg,  which  are  requi- 
site either  to  complete  its  structure,  or  to  provide  for  the  nutrition 
of  the  embryo. 

In  the  frog,  for  example,  the  oviduct  commences  at  the  upper 
part  of  the  abdomen  by  a  rather  wide  orifice,  which  communicates 
directly  with  the  peritoneal  cavity.  It 
soon  after  contracts  to  a  narrow  tube, 
and  pursues  a  zigzag  course  down  the 
side  of  the  abdomen  (Fig.  161),  folded 
upon  itself  in  convolutions,  like  the 
small  intestine,  until  it  opens,  near  its 
fellow  of  the  opposite  side,  into  the 
"cloaca,"  or  lower  part  of  the  intestinal 
canal.  The  oviducts  present  the  same 
general  characters  with  those  described 
above,  in  nearly  all  species  of  reptiles 
and  birds ;  though  there  are  some  modi- 
fications, in  particular  instances,  which 
do  not  require  any  special  notice. 

The  ovaries,  as  well  as  the  egg  which 
they  contain,  undergo  at  particular  sea- 
sons a  periodical  development  or  increase 
in  growth.  If  we  examine  the  female 
frog  iti  the  latter  part  of  summer  or  the 
fall,  we  shall  find  the  ovaries  presenting 

the  appearance  of  small  clusters  of  minute  and  nearly  colorless 
eggs,  the  smaller  of  which  are  perfectly  transparent  and  not  over 
y^o  of  an  inch  in  diameter.  But  in  the  early  spring,  when  the 
season  of  reproduction  approaches,  the  ovaries  will  be  found  in- 
creased to  four  or  five  times  their  former  size,  and  forming  large 
lobulated  masses,  crowded  with  dark-colored  opaque  eggs,  measur- 
^i''g  T-2  of  ^^  ii^ch  in  diameter.  At  the  approach  of  the  generative 
season,  in  all  the  lower  animals,  a  certain  number  of  the  eggs,  which 
were  previously  in  an  imperfect  and  inactive  condition,  begin  to  in- 
crease in  size  and  become  somewhat  altered  in  structure.  The  vitel- 
lus  more  especially,  which  was  before  colorless  and  transparent, 
becomes  granular  in  texture  as  well  as  increased  in  volume ;  and 
assumes  at  the  same  time,  in  many  species  of  animals,  a  black, 
brown,  yellow,  or  orange  color.  In  the  human  subject,  however, 
29 


Female  Generative  Or- 
gans OF  Frog. — a,  a  Ovaries. 
b,  b.  Oviducts,  e,  c.  Tlieir  intertiiil 
oi-ifices.  d.  Cloaca,  shovviug  exter- 
nal orifices  of  oviducts. 


450    EGG  AND  FEMALE  ORGANS  OF  GENERATION. 

the  change  consists  only  in  an  increase  of  size  and  granulation, 
without  any  remarkable  alteration  of  color. 

The  eggs,  as  they  ripen  in  this  way,  becoming  enlarged  and 
changed  in  texture,  gradually  distend  the  Graafian  follicles  and 
project  from  the  surface  of  the  ovary.  At  last,  when  fully  ripe, 
they  are  discharged  by  a  rupture  of  the  walls  of  the  follicles,  and, 
passing  into  the  oviducts,  are  conveyed  by  them  to  the  external 
generative  orifice,  and  there  expelled.  In  this  way,  as  successive 
seasons  come  round,  successive  crops  of  eggs  enlarge,  ripen,  leave 
the  ovaries,  and  are  discharged.  Those  which  are  to  be  expelled 
at  the  next  generative  epoch  may  always  be  recognized  by  their 
greater  degree  of  development;  and  in  this  way,  in  many  animals, 
the  eggs  of  no  less  than  three  different  crops  may  be  recognized  in 
the  ovary  at  once,  viz.,  1st,  those  which  are  perfectly  mature  and 
ready  to  be  discharged ;  2d,  those  which  are  to  ripen  in  the  follow- 
ing season ;  and  3d,  those  which  are  as  yet  altogether  inactive  and 
undeveloped.  In  most  fish  and  reptiles,  as  well  as  in  birds,  this 
regular  process  of  maturation  and  discharge  of  eggs  takes  place 
but  once  a  year.  In  different  species  of  quadrupeds  it  may  take 
place  annually,  semi-annually,  bimonthly,  or  even  monthly;  but 
in  every  instance  it  recurs  at  regular  intervals,  and  exhibits  accord- 
ingly, in  a  marked  degree,  the  periodic  character  which  we  have 
seen  to  belong  to  most  of  the  other  vital  phenomena. 

Action  of  the  Oviducts  and  Female  Generative  Passages. — In  frogs 
and  lizards,  the  ripening  and  discharge  of  the  eggs  take  place,  as 
above  mentioned,  in  the  early  spring.  At  the  time  of  leaving  the 
ovary,  the  eggs  consist  simply  of  the  dark  colored  and  granulnr 
vitellus,  inclosed  in  the  vitelline  membrane.  They  are  then  received 
by  the  inner  extremity  of  the  oviducts,  and  carried  downward  by 
the  peristaltic  movement  of  these  canals,  aided  by  the  more  power- 
ful contraction  of  the  abdominal  mus- 
Fig.  162.  cles.    During  the  passage  of  the  eggs, 

moreover,  the  mucous  membrane  of 
the  oviduct  secretes  a  colorless,  viscid, 


%*•  (®  "  *  ^  -<       albuminoid  substance,  which  is  depo- 

•®  ^-7  ^-V**)       sited  in  successive  layers  round  each 


»  %ti^  ggg^  forming  a  thick  and  tenacious 

Mature  Frogs'  eogs.-«.  While    coating or envclopc.  (Fig.  162.)  When 
«tiii  in  the  ovary.    6.  After  passing    ^^^  ^^^  finally  discharged,  this 

through  the  oviduct.  OO  .  -^  o       ' 

albuminoid  matter  absorbs  the  water 
in  which  the  spawn  is  deposited,  and  swells  up  into  a  transparent 


EGG  AND  FEMALE  ORGANS  OF  GENERATION.    451 

gelatinous  mass,  in  which  the  eggs  are  separately  imbedded.  This 
substance  supplies,  by  its  subsequent  liquefaction  and  absorption, 
a  certain  amount  of  nutritious  material,  during  the  development 
and  early  growth  of  the  embryo. 

In  the  terrestrial  reptiles  and  in  birds,  the  oviducts  perform  a 
still  more  important  secretory  function.  In  the  common  fowl,  the 
ovary  consists,  as  in  the  frog,  of  a  large  number  of  follicles,  loosely 
connected  by  areolar  tissue,  in  which  the  eggs  can  be  seen  in  different 
stages  of  development.  (Fig,  ld3,  a.)  As  the  egg  which  is  approach- 
ing maturity  enlarges,  it  distends  the  cavity  of  its  follicle  and  pro- 
jects farther  from  the  general  surface  of  the  ovary;  so  that  it  hangs 
at  last  into  the  peritoneal  cavity,  retained  only  by  the  attenuated 
wall  of  the  follicle,  and  a  slender  pedicle  through  which  run  the 
bloodvessels  by  which  its  circulation  is  supplied.  A  rupture  of  the 
follicle  then  occurs,  at  its  most  prominent  part,  and  the  egg  is  dis- 
charged from  the  lacerated  opening. 

At  the  time  of  its  leaving  the  ovary,  the  egg  of  the  fowl  consists 
of  a  large,  globular,  orange-colored  vitellus,  or  "  yolk,"  inclosed  in 
a  thin  and  transparent  vitelline  membrane.  Immediately  under- 
neath the  vitelline  membrane,  at  one  point  upon  the  surface  of  tlie 
vitellus,  is  a  round  white  spot,  consisting  of  a  layer  of  minute 
granules,  termed  the  ''cicatricula."  It  is  in  the  central  part  of  the 
cicatricula  that  the  germinative  vesicle  is  found  imbedded,  at  an 
early  stage  of  the  development  of  the  egg.  At  the  time  of  its 
discharge  from  the  ovary,  the  germinative  vesicle  has  usually  dis- 
appeared ;  but  the  cicatricula  is  still  a  very  striking  and  important 
part  of  the  vitellus,  as  it  is  from  this  spot  that  the  body  of  the  chick 
begins  afterward  to  be  developed. 

At  the  same  time  that  the  egg  protrudes  from  the  surface  of  the 
ovary,  it  projects  into  the  inner  orifice  of  the  oviduct ;  so  that;  when 
discharged  from  its  follicle,  it  is  immediately  embraced  by  the  upper 
or  fringed  extremity  of  this  tube,  and  commences  its  passage  down- 
ward. In  the  fowl,  the  muscular  coat  of  the  oviduct  is  highly  deve- 
loped, and  its  peristaltic  contractions  gently  urge  the  egg  from  above 
downward,  precisely  as  the  oesophagus  or  the  intestines  transport  the 
food  in  a  similar  direction.  While  passing  through  the  first  two  or 
three  inches  of  the  oviduct  (c,  <i),  where  the  mucous  membrane  is 
smooth  and  transparent,  the  yolk  merely  absorbs  a  certain  quantity 
of  fluid,  so  as  to  become  more  flexible  and  yielding  in  consistency. 
It  then  passes  into  a  second  division  of  the  generative  canal,  in 
which  the  raucous  membrane  is  thick  and  glandular  in  texture,  and 


452    EGG  AND  FEMALE  ORGANS  OF  GENERATION. 

•is  also  thrown  into  numerous  longitudinal  folds,  which  project  into 
the  cavity  of  the  oviduct.  This  portion  of  the  oviduct  (o?,  e)  extends 
over  about  nine  inches  of  its  entire  length.  In  its  upper  part,  the 
mucous  membrane  secretes  a  viscid  material,  by  which  the  yolk  is 
encased,  and  which  soon  consolidates  into  a  gelatinous,  membranous 
deposit;  thus  forming  a  second  homogeneous  layer,  outside  the 
vitelline  membrane. 

Now  the  peristaltic  movements  of  this  part  of  the  oviduct  are 
such  as  to  give  a  rotatory,  as  well  as  a  progressive  motion  to  the 
egg ;  and  the  two  extremities  of  the  membranous  layer  described 
above  become,  accordingly,  twisted,  in  opposite  directions,  into  two 
fine  cords,  which  run  backward  and  forward  from  the  opposite  poles 
of  the  egg.  These  cords  are  termed  the  "chalazte,"  and  the  membrane 
with  which  they  are  connected,  the  "  chalaziferous  membrane." 

Throughout  the  remainder  of  the  second  division  of  the  oviduct, 
the  mucous  membrane  exudes  an  abundant,  gelatinous,  albuminoid 
substance,  which  is  deposited  in  successive  layers  round  the  yolk, 
inclosing  at  the  same  time  the  chalaziferous  membrane  and  the 
chalazee.  This  substance,  which  forms  the  so-called  albumen,  or 
"  white  of  egg,"  is  semi-solid  in  consistency,  nearly  transparent,  and 
of  a  faint  amber  color.  It  is  deposited  in  greater  abundance  in  front 
of  the  advancing  Qgg  than  behind  it,  and  forms  accordingly  a 
pointed  or  conical  projection  in  front,  while  behind,  its  outline  is 
rounded  off,  parallel  with  the  spherical  surface  of  the  yolk.  In  this 
way,  the  egg  acquires,  when  covered  with  its  albumen,  an  ovoid 
form,  of  which  one  end  is  round,  the  other  pointed ;  the  pointed 
extremity  being  always  directed  downward,  as  the  egg  descends 
along  the  oviduct. 

In  the  third  division  of  the  oviduct  (/),  which  is  about  three  and 
a  half  inches  in  length,  the  mucous  membrane  is  arranged  in  longi- 
tudinal folds,  which  are  narrower  and  more  closely  packed  than  in 
the  preceding  portion.  The  material  secreted  in  this  part,  and  de- 
posited upon  the  egg^  condenses  into  a  firm  fibrous  covering,  com- 
posed of  three  different  layers  which  closely  embrace  the  surface 
of  the  albuminous  mass,  forming  a  tough,  flexible,  semi-opaque 
envelope  for  the  whole.  These  layers  are  known  as  the  external, 
middle,  and  internal  fibrous  membranes  of  the  egg. 

Finally  the  egg  passes  into  the  fourth  division  of  the  oviduct  [g)^ 
which  is  wider  than  the  rest  of  the  canal,  but  only  a  little  over  two 
inches  in  length.  Here  the  mucous  membrane,  which  is  arranged 
in  abundant,  projecting,  leaf-like  villosities,  exudes  a  fluid  very  rich 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


453 


in  calcareous  salts.  The  most  external  of  the  three  membranes 
just  described  is  permeated  by  this  fluid,  and  very  soon  the  calcare- 
ous matter  begins  to  crystallize  in  the  interstices  of  its  fibres.  This 
deposit  of  calcareous  matter  goes  on,  growing  constantly  thicker 
and  more  condensed,  until  the  entire 
external  membrane  is  converted  into  Fig.  163. 

a  white,  opaque,  brittle,  calcareous 
shell,  which  incloses  the  remaining 
portions  and  protects  them  from  ex- 
ternal injury.  The  egg  is  then  driven 
outward  by  the  contraction  of  the 
muscular  coat  through  a  narrow  por- 
tion of  the  oviduct  (A),  and,  gradually 
dilating  the  passages  by  its  conical 
extremity,  is  finally  discharged  from 
the  external  orifice. 

The  egg  of  the  fowl,  after  it  has 
been  discharged  from  the  body,  con- 
sists, accordingly,  of  various  parts; 
some  of  which,  as  the  yolk  and  the 
vitelline  membrane,  entered  into  its 
original  formation,  while  the  remain- 
der have  been  deposited  round  it  dur- 
ing its  passage  through  the  oviduct. 
On  examining  such  an  egg  (Fig.  164), 
we  find  externally  the  calcareous 
shell  (/i),  while  immediately  beneath 
it  are  situated  the  middle  and  internal 
fibrous  shell-membranes  (e,/). 

Soon  after  the  expulsion  of  the  egg 
there  is  a  partial  evaporation  of  its 
watery  ingredients,  which  are  replaced 
by  air  penetrating  through  the  pores 
of  the  shell  at  its  rounded  extremity. 
The  air  thus  introduced  accumulates 
between  the  middle  and  internal 
fibrous  membranes  at  this  spot,  sepa- 

Female  Generative  Organs  o*  Fowl  —a.  Ovary.  6.  Graafian  vesicle,  from  which  (he 
egg  has  j ust  been  discharged,  c.  Yolk,  entering  upper  extremity  of  oviduct,  d,  e.  Second  division 
of  oviduct,  in  vrhich  chalaziferous  membrane,  chalazje,  and  albumen  are  formed.  /.  Third  portion, 
in  which  the  fibrous  shell  membranes  are  produced,  ff.  Fourth  portion  laid  open,  showing  egg  com- 
pletely formed,  with  calcareous  shell,     h.  Narrow  canal  through  which  the  egg  is  dlt^charged. 


454 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


rating  them  from  each  other,  and  forming  a  cavity  or  air-chamber 
{g\  which  is  always  found  between  the  two  fibrous  membranes  at 
the  rounded  end  of  the  egg.  Next  we  come  to  the  albumen  or 
"  white"  of  the  egg  {d) ;  next  to  the  chalaziferous  membrane  and 
chalazae  (c);  and  finally  to  the  vitelline  membrane  {h)  inclosing  the 


Fig.  164. 


Diagram  of  Fowl' s  Egg. — a.  Yolk.     b.  Vitelline  membrane,     c.  Chalaziferous  membrane,    d. 
Albumen,    e.  f   Middle  and  internal  shell  membranes,     g.  Air-chamber,    h.  Calcareous  shell. 

yolk  (a).  After  the  expulsion  of  the  egg,  the  external  layers  of  the 
albumen  liquefy ;  and  the  vitellus,  being  specifically  lighter  than 
the  albumen,  owing  to  the  large  proportion  of  oleaginous  matter 
which  it  contains,  rises  toward  the  surface  of  the  egg,  with  the  cica- 
tricula  uppermost.  This  part,  therefore,  presents  itself  almost  im- 
mediately on  breaking  open  the  egg  upon  its  lateral  surface,  and  is 
placed  in  the  most  favorable  position  for  the  action  of  warmth  and 
atmospheric  air  in  the  development  of  the  chick. 

The  vitellus,  therefore,  is  still  the  essential  and  constituent  portion 
of  the  egg;  while  all  the  other  parts  consist  either  of  nutritious  mate- 
rial, like  the  albumen,  provided  for  the  support  of  the  embryo,  or 
of  protective  envelopes,  like  the  shell  and  the  fibrous  membranes. 

In  the  quadrupeds,  another  and  still  more  important  modification 
of  the  oviducts  takes  place.  In  these  animals,  the  egg,  which  is 
originally  very  minute  in  size,  is  destined  to  be  retained  within  the 
generative  passages  of  the  female  during  the  development  of  the 
embryo.  While  the  upper  part  of  the  oviduct,  therefore,  is  quite 
narrow,  and  intended  merely  to  transmit  the  egg  from  the  ovary, 
and  to  supply  it  with  a  little  albuminous  secretion,  its  lower  por- 
tions are  very  much  increased  in  size,  and  are  lined,  moreover,  with 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


455 


a  mucous  membrane,  so  constructed  as  to  provide  for  the  protection 
and  nourishment  of  the  embryo,  during  the  entire  period  of  gesta- 
tion. The  upper  and  narrower  portions  of  the  oviduct  are  known 
as  the  "Fallopian  tubes"  (Fig.  165);   while  the  lower  and  more 


Fig.  165. 


Utkri-s    and   Ovaries   of   thr   Sow. — a,  n.  Ovaries.     h,h.  Fallopiau  tubes,    c,  c.  Horns  of 
uterus,     d.   Body  of  uterus,     e.   Vagiua. 

highly  developed  portions  constitute  the  uterus.  These  lower  por- 
tions unite  with  each  other  upon  the  median  line  near  their  infe- 
rior termination,  so  as  to  form  a  central  organ,  termed  the  "  body" 
of  the  uterus;  while  the  remaining  ununited  parts  are  known  as 
its  "cornua,"  or  "horns." 

In  the  human  subject,  the  female  generative  apparatus  presents 
the  following  peculiarities.  The  ovaries  consist  of  Graafian  follicles, 
which  are  imbedded  in  a  somewhat  dense  areolar  tissue,  supplied 
with  an  abundance  of  bloodvessels.  The  entire  mass  is  covered 
with  a  thick,  opaque,  yellowish-white  layer  of  fibrous  tissue,  called 
the  "albuglneous  tunic."  Over  the  whole  is  a  layer  of  peritoneum, 
which  is  reflected  upon  the  vessels  which  supply  the  ovary,  and  is 
continuous  with  the  broad  ligaments  of  the  uterus. 

The  oviducts  commence  by  a  wide  expansion,  provided  with 
fringed  edges,  called  the  "  fimbriated  extremity  of  the  Fallopian 
tube."  The  Fallopian  tubes  themselves  are  very  narrow  and  con- 
voluted, and  terminate  on  each  side  in  the  upper  part  of  the  body 
of  the  uterus.  In  the  human  subject,  the  body  of  the  uterus  is  so 
much  developed  at  the  expense  of  the  cornua,  that  the  latter  hardly 
appear  to  have  an  existence;  and  in  fact  no  trace  of  them  is  visible 
externally.  But  on  opening  the  body  of  the  uterus  its  cavity  is 
seen  to  be  nearly  triangular  in  shape,  its  two  superior  angles  run- 
ning out  on  each  side  to  join  the  lower  extremities  of  the  Fallopian 
tabes.     This  portion  evidently  consists  of  the  cornua,  which  .have 


456 


EGG  AND  FEMALE  ORGANS  OF  GENERATION. 


been  consolidated  with  the  body  of  the  uterus,  and  enveloped  in 
its  thickened  layer  of  muscular  fibres. 


Fig.  166. 


Generative    Organs    of     He; man     Female. — a,  a.    Ovaries.      6,  6.    Fallopian    tubes, 
e.  Body  of  uterus,    d.  Cervix,     e.  Vagiua. 

The  cavity  of  the  body  of  the  uterus  terminates  below  by  a  con- 
stricted portion  termed  the  os  internum,  by  which  it  is  separated 
from  the  cavity  of  the  cervix.  These  two  cavities  are  not  only 
different  from  each  other  in  shape,  but  differ  also  in  the  structure 
of  their  mucous  membrane  and  the  functions  which  it  is  destined 
to  perform. 

The  mucous  membrane  of  the  body  of  the  uterus  in  its  usual 
condition  is  smooth  and  rosy  in  color,  and  closely  adherent  to  the 
subjacent  muscular  tissue.  It  consists  of  minute  tubular  follicles 
somewhat  similar  to  those  of  the  gastric  mucous  membrane,  ranged 
side  by  side,  and  opening  by  distinct  orifices  upon  its  free  surface. 
The  secretion  of  these  follicles  is  destined  for  the  nutrition  of  the 
embryo  during  the  earlier  periods  of  its  formation. 

The  internal  surface  of  the  neck  of  the  uterus,  on  the  other  hand, 
is  raised  in  prominent  ridges,  which  are  arranged  usually  in  two 
lateral  sets,  diverging  from  a  central  longitudinal  ridge;  presenting 
the  appearance  known  as  the  "arbor  Yitsa  uterina."  The  follicles 
of  this  part  of  the  uterine  mucous  membrane  are  different  in  struc- 
ture from  those  of  the  foregoing.  They  are  of  a  globular  or  sac- 
like form,  and  secrete  a  very  firm,  adhesive,  transparent  mucus, 
which  is  destined  to  block  up  the  cavity  of  the  cervix  during  ges- 


EGG  AND  FEMALE  ORGANS  OF  GENERATION.    457 

tation,  and  guard  against  the  accidental  displacement  of  the  egg. 
Some  of  these  follicles  are  frequently  distended  with  their  secretion, 
and  project,  as  small,  hard,  rounded  eminences,  from  the  surface 
of  the  mucous  membrane.  In  this  condition  they  are  sometimes 
designated  by  the  name  of  "  ovula  Nabothi,"  owing  to  their  having 
been  formerly  mistaken  for  eggs,  or  ovules. 

The  cavity  of  the  cervix  uteri  is  terminated  below  by  a  second 
constriction,  the  "os  externum."  Below  this  comes  the  vagina, 
which  constitutes  the  last  division  of  the  female  generative  pas- 
sages. 

The  accessory  female  organs  of  generation  consist  therefore  of 
ducts  or  tubes,  by  means  of  which  the  egg  is  conveyed  from  within 
outward.  These  ducts  vary  in  the  degree  and  complication  of 
their  development,  according  to  the  importance  of  the  task  assigned 
to  them.  In  the  lower  orders,  they  serve  merely  to  convey  the  egg- 
rapidly  to  the  exterior,  and  to  supply  it  more  or  less  abundantly 
with  an  albuminous  secretion.  In  the  higher  classes  and  in  the 
human  subject,  they  are  adapted  to  the  more  important  function  of 
retaining  the  egg  during  the  period  of  gestation,  and  of  providing 
during  the  same  time  for  the  nourishment  of  the  young  embryo. 


458  MALE  OKGANS  OF  GENERATION, 


CHAPTER   ly. 

ON  Xrf^  SPERMATIC  FLUID,  AND  THE   MALE  ORGANS 
OF   GENERATION. 

The  mature  egg  is  not  by  itself  capable  of  being  developed  into 
the  embryo.  If  simply  discharged  from  the  ovary  and  carried 
through  the  oviducts  toward  the  exterior,  it  soon  dies  and  is  de- 
composed, like  any  other  portion  of  the  body  separated  from  its 
natural  connections.  It  is  only  when  fecundated  by  the  spermatic 
fluid  of  the  male,  that  it  is  stimulated  to  continued  development, 
and  becomes  capable  of  a  more  complete  organization. 

The  product  of  the  male  generative  organs  consists  of  a  colorless, 
somewhat  viscid,  and  albuminous  fluid,  containing  an  innumerable 
quantity  of  minute  filamentous  bodies,  termed  spermatozoa.  The 
name  spermatozoa  has  been  given  to  these  bodies,  on  account  of 
their  exhibiting  under  the  microscope  a  very  active  and  continu- 
ous movement,  bearing  some  resemblance  to  that  of  certain  animal- 
cules. 

The  spermatozoa  of  the  human  subject  (Fig.  167,  a)  are  about 
g^o  of  an  inch  in  length,  according  to  the  measurements  of  Kol- 
liker.  Their  anterior  extremity  presents  a  somewhat  flattened, 
triangular-shaped  enlargement,  termed  the  "head."  The  head  con- 
stitutes about  one-tenth  part  the  entire  length  of  the  spermato- 
zoon. The  remaining  portion  is  a  very  slender  filamentous  pro- 
longation, termed  the  "tail,"  which  tapers  gradually  backward, 
becoming  so  exceedingly  delicate  towards  its  extremity,  that  it  is 
difiicult  to  be  seen  except  when  in  motion.  There  is  no  further 
organization  or  internal  structure  to  be  detected  in  any  part  of  the 
spermatozoon ;  and  the  whole  appears  to  consist,  so  far  as  can  be 
seen  by  the  microscope,  of  a  completely  homogeneous,  tolerably 
firm,  albuminoid  substance.  The  terms  head  and  tail,  therefore, 
as  justly  remarked   by  Bergmann  and  Leuckart,'  are  not   used, 

'  Vergleichende  Physiologic.     Stuftgnrt,  1852. 


MALE  ORGANS  OF  GENERATION. 


459 


when  describing  the  different  parts  of  the  spermatozoon,  in  the 
sanae  sense  as  that  in  which  they  would  be  applied  to  the  corre- 
sponding parts  of  an  animal,  but  simply  for  the  sake  of  conveni- 
ence; just  as  one  might  speak  of  the  head  of  an  arrow,  or  the  tail 
of  a  comet. 

In  the  lower  animals,  the  spermatozoa  have  usually  the  same 
general  form  as  in  the  human  subject ;  that  is,  they  are  slender 
filamentous  bodies,  with  the  anterior  extremity  more  or  less  en- 
larged. In  the  rabbit  they  have  a  head  which  is  roundish  and 
flattened  in  shape,  somewhat  resembling  the  globules  of  the  blood. 
In  the  rat  (Fig.  167,  b)  they  are  much  larger  than  in  man,  raeasur- 

Fig.  167. 


Spkrmatozoa. — a.  Humao.    b.  Of  Rat.     c.  Of  Menobranchus.     Magnified  4S0  times. 


ing  nearly  y^?  of  an  inch  in  length.  The  head  is  conical  in  shape, 
about  one-twentieth  the  whole  length  of  the  filament,  and  often 
slightly  curved  at  its  anterior  extremity.  In  the  frog  and  in  rep- 
tiles generally,  the  spermatozoa  are  longer  than  in  quadrupeds. 
In  the  Menobranchus,  or  great  American  water-lizard,  they  are  of 
very  unusual  size  (Fig.l(>7,  c),  measuring  not  less  than  ^\  of  an 


460  MALE  ORGANS  OF  GENERATION. 

inch  in  length,  about  one-third  of  which  is  occupied  by  the  head, 
or  enlarged  portion  of  the  filament. 

The  most  remarkable  peculiarity  of  the  spermatozoa  is  their 
very  singular  and  active  movement,  to  which  we  have  already 
alluded.  If  a  drop  of  fresh  seminal  fluid  be  placed  under  the 
microscope,  the  numberless  minute  filaments  with  which  it  is 
crowded  are  seen  to  be  in  a  state  of  incessant  and  agitated  motion. 
This  movement  of  the  spermatozoa,  in  many  species  of  animals, 
strongly  resembles  that  of  the  tadpole;  particularly  when,  as  in 
the  human  subject,  the  rabbit,  &c.,  the  spermatozoa  consist  of  a 
short  and  well  defined  head,  followed  by  a  long  and  slender  tail. 
Here  the  tail-like  filament  keeps  up  a  constant  lateral  or  vibratory 
movement,  by  which  the  spermatozoon  is  driven  from  place  to 
place  in  the  spermatic  fluid,  just  as  the  fish  or  the  tadpole  is  pro- 
pelled through  the  water.  In  other  instances,  as  for  example  in 
the  water-lizard,  and  in  some  parasitic  animals,  the  spermatozoa 
have  a  continuous  writhing  or  spiral-like  movement,  which  pre- 
sents a  very  peculiar  and  elegant  appearance  when  large  numbers 
of  them  are  viewed  together. 

It  is  the  existence  of  this  movement  which  first  suggested  the 
name  of  spermatozoa  to  designate  the  animated  filaments  of  the 
spermatic  fluid ;  and  which  has  led  some  writers  to  attribute  to 
them  an  independent  animal  nature.  This  is,  however,  a  very 
erroneous  mode  of  regarding  them ;  since  they  cannot  properly  be 
considered  as  animals,  notwithstanding  the  active  character  of  their 
movement,  and  the  striking  resemblance  which  it  sometimes  pre- 
sents to  a  voluntary  act.  The  spermatozoa  are  organic  forms, 
which  are  produced  in-  the  testicles,  and  constitute  a  part  of  their 
tissue ;  just  as  the  eggs,  which  are  produced  in  the  ovaries,  natu- 
rally form  a  part  of  the  texture  of  these  organs.  Like  the  egg, 
also,  the  spermatozoon  is  destined  to  be  discharged  from  the  organ 
where  it  grew,  and  to  retain,  for  a  certain  length  of  time  afterward, 
its  vital  properties.  One  of  the  most  peculiar  of  these  properties 
is  its  power  of  keeping  in  constant  motion  ;  which  does  not,  how- 
ever, mark  it  as  a  distinct  animal,  but  only  distinguishes  it  as  a 
peculiar  structure  belonging  to  the  parent  organism.  The  motion 
of  a  spermatozoon  is  precisely  analogous  to  that  of  a  ciliated  epi- 
thelium cell.  The  movement  of  the  latter  will  continue  for  some 
hours  after  it  has  been  separated  from  its  mucous  membrane,  pro- 
vided its  texture  be  not  injured,  nor  the  process  of  decomposition 
allowed  to  commence.     In  the  same  manner,  the  movement  of  the 


MALE  ORGANS  OF  GENERATION.        •   461 

spermatozoa  is  a  characteristic  property  belonging  to  them,  which 
continues  for  a  certain  time,  even  after  they  have  been  separated 
from  all  connection  with  the  rest  of  the  body. 

In  order  to  preserve  their  vitality,  the  spermatozoa  must  be 
kept  at  the  ordinary  temperature  of  the  body,  and  preserved 
from  the  contact  of  the  air  or  other  unnatural  fluids.  In  this  way, 
they  may  be  kept  without  difficulty  many  hours  for  purposes  of 
examination.  But  if  the  fluid  in  which  they  are  kept  be  allowed 
to  dry,  or  if  it  be  diluted  by  the  addition  of  water,  in  tli'e  case 
of  birds  and  quadrupeds,  or  if  it  be  subjected  to  extremes  of  heat 
or  cold,  the  motion  ceases,  and  the  spermatozoa  themselves  soon 
begin  to  disintegrate. 

The  spermatozoa  are  produced  in  certain  glandular-looking 
organs,  the  testicles^  w^hich  are  characteristic  of  the  male,  as  the 
ovaries  are  characteristic  of  the  female.  In  man  and  all  the  higher 
animals,  the  testicles  are  solid,  ovoid-shaped  bodies,  composed 
principally  of  numerous  long,  narrow,  and  convoluted  tubes,  the 
"seminiferous  tubes,"  somewhat  similar  in  their  general  anatomical 
characters  to  the  tubuli  uriniferi  of  the  kidneys.  These  tubes  lie 
for  the  most  part  closely  in  contact  with  each  other,  so  that  nothing 
intervenes  between  them  except  capillary  bloodvessels  and  a  little 
areolar  tissue.  They  commence,  by  blind,  rounded  extremities,  near 
the  external  surface  of  the  testicle,  and  pursue  an  intricately  con- 
voluted course  toward  its  central  and  posterior  part.  They  are 
not  strongly  adherent  to  each  other,  but  may  be  readily  unravelled 
by  manipulation,  and  separated  from  each  other. 

The  formation  of  the  spermatozoa,  as  it  takes  place  in  the 
substance  of  the  testicle,  has  been  fully  investigated  by  Kolliker. 
According  to  his  observations,  as  the  age  of  puberty  approaches, 
beside  the  ordinary  pavement  epithelium  lining  the  seminiferous 
tubes,  other  cells  or  vesicles  of  larger  size  make  their  appearance 
in  these  tubes,  each  containing  from  one  to  fifteen  or  twenty  nuclei, 
with  nucleoli.  It  is  in  the  interior  of  these  vesicles  that  the 
spermatozoa  are  formed ;  their  number  corresponding  usually  with 
that  of  the  nuclei  just  mentioned.  They  are  at  first  developed  in 
bundles  of  ten  to  twenty,  held  together  by  the  thin  membranous 
substance  which  surrounds  them,  but  are  afterward  set  free  by  the 
liquefaction  of  the  vesicle,  and  then  fill  nearly  the  entire  cavity  of 
the  seminiferous  ducts,  mingled  only  with  a  YGvy  minute  quantity 
of  transparent  fluid. 

In  the  seminiferous  tubes  themselves,  the  spermatozoa  are  always 


462  MALE  ORGANS  OF  GENERATION, 

inclosed  in  the  interior  of  their  parent  vesicles;  they  are  liberated, 
and  mingled  promiscuously  together,  only  after  entering  the  rete 
testis  and  the  head  of  the  epididymis. 

Beside  the  testicles,  which  are,  as  above  stated,  the  primary  and 
essential  parts  of  the  male  generative  apparatus,  there  are  certain 
secondary  or  accessory  organs,  by  means  of  which  the  spermatic 
fluid  is  conveyed  to  the  exterior,  and  mingled  with  certain  secre- 
tions .which  assist  in  the  accomplishment  of  its  functions. 

As  the  sperm  leaves  the  testicle,  it  consists,  as  above  mentioned, 
almost  entirely  of  the  spermatozoa,  crowded  together  in  an  opaque, 
white,  semi-fluid  mass,  which  fills  up  the  vasa  eflferentia,  and  com- 
pletely distends  their  cavities.  It  then  enters  the  single  duct 
which  forms  the  body  and  lower  extremity  of  the  epididymis, 
following  the  long  and  tortuous  course  of  this  tube,  until  it 
becomes  continuous  with  the  vas  deferens;  through  which  it  is  still 
conveyed  onward  to  the  point  where  this  canal  opens  into  the 
urethra.  Throughout  this  course,  it  is  mingled  with  a  glairy, 
mucus-like  fluid,  secreted  by  the  walls  of  the  epididymis  and  vas 
deferens,  in  which  the  spermatozoa  are  enveloped.  The  mixture 
is  then  deposited  in  the  vesiculee  seminales,  where  it  accumulates 
as  fresh  quantities  are  produced  in  the  testicle  and  conveyed  down- 
ward by  the  spermatic  duct.  It  is  probable  that  a  second  secretion 
is  supplied  also  by  the  internal  surface  of  the  vesiculs  seminales, 
and  that  the  sperm,  while  retained  in  their  cavities,  is  not  only 
stored  up  for  subsequent  use,  but  is  at  the  same  time  modified  in 
its  properties  by  the  admixture  of  another  fluid. 

At  the  time  when  the  evacuation  of  the  sperm  takes  place,  it  is 
driven  out  from  the  seminal  vesicles  by  the  muscular  contraction 
of  the  surrounding  parts,  and  meets  in  the  urethra  with  the  secre- 
tions of  the  prostate  gland,  the  glands  of  Cowper,  and  the  mucous 
follicles  opening  into  the  urethral  passage.  All  these  organs  are  at 
that  time  excited  to  an  unusual  activity  of  secretion,  and  pour  out 
their  different  fluids  in  great  abundance. 

The  sperm,  therefore,  as  it  is  discharged  from  the  urethra,  is  an 
exceedingly  mixed  fluid,  consisting  of  the  spermatozoa  derived 
from  the  testicles,  together  with  the  secretions  of  the  epididymis 
and  vas  deferens,  the  prostate,  Cowper's  glands,  and  the  mucous 
follicles  of  the  urethra.  Of  all  these  ingredients,  it  is  the  sperma- 
tozoa which  constitute  the  essential  part  of  the  seminal  fluid.  They 
are  the  true  fecundating  element  of  the  sperm,  while  all  the  others 
are  secondary  in  importance  and  perform  only  accessory  functions. 

Spallanzani  found  that  if  frog's  semen  be  passed  through  a  sue- 


MALE  OEGANS  OF  GENERATION.  463 

cession  of  filters,  so  as  to  separate  the  spermatozoa  from  the  liquid 
portions,  the  filtered  fluid  is  destitute  of  any  fecundating  properties; 
while  the  spermatozoa  remaining  entangled  in  the  filter,  if  mixed 
with  a  sufficient  quantity  of  fluid  of  the  requisite  density  for  dilu- 
tion, may  still  be  successfully  used  for  the  impregnation  of  eggs. 
It  is  well  known,  also,  that  animals  or  men  from  whom  both 
testicles  have  been  removed,  are  incapable  of  impregnating  the 
female  or  her  eggs  ;  while  a  removal  or  imperfection  of  any  of  the 
other  generative  organs  does  not  necessarily  prevent  the  accom- 
plishment of  the  function. 

In  most  of  the  lower  orders  of  animals  there  is  a  periodical 
development  of  the  testicles  in  the  male,  corresponding  in  time  with 
that  of  the  ovaries  in  the  female.  As  the  ovaries  enlargje  and  the 
eggs  ripen  in  the  one  sex,  so  in  the  other  the  testicles  increase  in 
size,  as  the  season  of  reproduction  approaches,  and  become  turgid 
with  spermatozoa.  The  accessory  organs  of  generation,  at  the 
same  time,  share  the  unusual  activity  of  the  testicles,  and  become 
increased  in  vascularity  and  ready  to  perform  their  part  in  the 
reproductive  function. 

In  the  fish,  for  example,  where  the  testicles  occupy  a  similar  posi- 
tion in  the  abdomen  as  the  ovaries  in  the  opposite  sex,  these  bodies 
enlarge,  become  distended  with  their  contents,  and  project  into  the 
peritoneal  cavity.  Each  of  the  two  sexes  is  then  at  the  same  time 
under  the  influence  of  a  corresponding  excitement.  The  unusual 
development  of  the  generative  organs  reacts  upon  the  entire  system, 
and  produces  a  state  of  peculiar  activity  and  excitability,  known  as 
the  condition  of  "erythism."  The  female,  distended  with  eggs,  feels 
the  impulse  which  leads  to  their  expulsion  ;  while  the  male,  bear- 
ing the  weight  of  the  enlarged  testicles  and  the  accumulation  of 
newly-developed  spermatozoa,  is  impelled  by  a  similar  sensation  to 
the  discharge  of  the  spermatic  fluid.  The  two  sexes,  accordingly, 
are  led  by  instinct  at  this  season  to  frequent  the  same  situations. 
The  female  deposits  her  eggs  in  some  spot  favorable  to  the  protec- 
tion and  development  of  the  young ;  after  which  the  male,  appa- 
rently attracted  and  stimulated  by  the  sight  of  the  new-laid  eggs, 
discharges  the  spermatic  fluid  upon  them,  and  their  impregnation 
is  accomplished. 

In  such  instances  as  the  above,  where  the  male  and  female  gene- 
rative products  are  discharged  separately  by  the  two  sexes,  the 
subsequent  contact  of  the  eggs  with  the  spermatic  fluid  would  seem 
to  depend  altogether  on  the  occurrence  of  fortuitous  circumstances, 
and  their  impregnation,  therefore,  be  often  liable  to  fail.     In  point 


464   *        MALE  ORGANS  OF  GENERATION. 

of  fact,  however,  the  simultaneous  functional  excitement  of  the 
two  sexes  and  the  operation  of  corresponding  instincts,  leading 
them  to  ascend  the  same  rivers  and  to  frequent  the  same  spots, 
provide  with  sufficient  certainty  for  the  impregnation  of  the  eggs. 
In  these  animals,  also,  the  number  of  eggs  produced  by  the  female 
is  very  large,  the  ovaries  being  often  so  distended  as  to  fill  nearly 
the  whole  of  the  abdominal  cavity;  so  that,  although  many  of  the 
eggs  may  be  accidentally  lost,  a  sufficient  number  will  still  be  im- 
pregnateid  and  developed  to  provide  for  the  continuation  of  the 
species. 

In  other  instances,  an  actual  contact  takes  place  between  the 
sexes  at  the  time  of  reproduction.  In  the  frog,  for  example,  the 
male  fastens  himself  upon  the  back  of  the  female  by  the  anterior 
extremities,  which  seem  to  retain  their  hold  by  a  kind  of  spasmodic 
contraction.  This  continues  for  one  or  two  days,  during  which 
time  the  mature  eggs,  which  have  been  discharged  from  the  ovary, 
are  passing  downward  through  the  oviducts.  At  last  they  are  ex- 
pelled from  the  anus,  while  at  the  same  time  the  seminal  fluid  of 
the  male  is  discharged  upon  them,  and  impregnation  takes  place. 

In  the  higher  classes  of  animals,  however,  and  in  man,  where  the 
egg  is  to  be  retained  in  the  body  of  the  female  parent  during  its 
development,  the  spermatic  fluid  is  introduced  into  the  female 
generative  passages  by  sexual  congi-ess,  and  meets  the  egg  at  or 
soon  after  its  discharge  from  the  ovary.  The  same  correspondence, 
however,  between  the  periods  of  sexual  excitement  in  the  male  and 
female,  is  visible  in  many  of  these  animals,  as  well  as  in  fish  and 
reptiles.  This  is  the  case  in  most  species  which  produce  young  but 
once  a  year,  and  at  a  fixed  period,  as  the  deer  and  the  wild  hog.  In 
other  species,  on  the  contrary,  such  as  the  dog,  as  well  as  the  rabbit, 
the  guinea  pig,  &c.,  where  several  broods  of  young  are  produced 
during  the  year,  or  where,  as  in  the  human  subject,  the  generative 
epochs  of  the  female  recur  at  short  intervals,  so  that  the  particular 
period  of  impregnation  is  comparatively  indefinite,  the  generative 
apparatus  of  the  male  is  almost  constantly  in  a  state  of  full  deve- 
lopment ;  and  is  excited  to  action  at  particular  periods,  apparently 
by  some  influence  derived  from  the  condition  of  the  female. 

In  the  quadrupeds,  accordingly,  and  in  the  human  species,  the 
contact  of  the  sperm  with  the  egg  aud  the  fecundation  of  the  latter 
take  place  in  the  generative  passages  of  the  female ;  either  in  the 
uterus,  the  Fallopian  tubes,  or  even  upon  the  surface  of  the  ovary ; 
in  each  of  which  situations  the  spermatozoa  have  been  found,  after 
the  accomplishment  of  sexual  intercourse. 


PERIODICAL    OVULATION.  465 


CHAPTER    V. 

ON    PERIODICAL    OVULATION,    AND    THE    FUNCTION 
OF   MENSTRUATION. 


L   PERIODICAL   OVULATION. 

We  have  already  spoken  in  general  terms  of  the  periodical  ripen- 
ing of  the  eggs  and  their  discharge  from  the  generative  organs  of 
the  female.  This  function  is  known  by  the  name  of  "  ovulation," 
and  may  be  considered  as  the  primary  and  most  important  act  in 
the  process  of  reproduction.  We  shall  therefore  enter  more  fully 
into  the  consideration  of  certain  particulars  in  regard  to  it,  by 
which  its  nature  and  conditions  may  be  more  clearly  understood. 

1st,  Eggs  exist  originally  in  the  ovaries  of  all  animals^  as  part  of 
their  natural  structure.  In  describing  the  ovaries  of  iish  and  reptiles 
we  have  said  that  they  consist  of  nothing  more  than  Graafian  vesi- 
cles, each  vesicle  containing  an  egg^  and  united  with  each  other  by 
loose  areolar  tissue  and  a  peritoneal  investment.  In  the  higher 
animals  and  in  the  human  subject,  the  essential  constitution  of  the 
ovary  is  the  same ;  only  its  fibrous  tissue  is  more  abundant,  so  that 
the  texture  of  the  entire  organ  is  more  dense,  and  its  figure  more 
compact.  In  all  classes,  however,  without  exception,  the  interior 
of  each  Graafian  vesicle  is  occupied  by  an  Qgg ;  and  it  is  from  this 
egg  that  the  young  ofispring  is  afterward  to  be  produced. 

The  process  of  reproduction  was  formerly  regarded  as  essentially 
different  in  the  oviparous  and  viviparous  animals.  In  the  ovipa- 
rous classes,  such  as  most  fish,  and  all  reptiles  and  birds,  the  young 
animal  was  well  known  to  be  formed  from  an  egg  produced  by  the 
female;  while  in  the  viviparous  animals,  or  those  which  brino- 
forth  their  young  alive,  such  as  the  quadrupeds  and  the  human 
species,  the  embryo  was  supposed  to  originate  in  the  body  of  the 
female,  by  some  altogether  peculiar  and  mysterious  process,  in 
consequence  of  sexual  intercourse.  As  soon,  however,  as  the 
microscope  began  to  be  used  in  the  examination  of  the  tissues, 
30 


466        OVULATION    AND    FUNCTION    OF    MENSTRUATION. 

the  ovaries  of  quadrupeds  were  also  found  to  contain  eggs.  These 
eggs  had  previously  escaped  observation  on  account  of  their  simple 
structure  and  minute  size ;  but  they  were  nevertheless  found  to 
possess  all  the  most  essential  characters  belonging  to  the  larger 
eggs  of  the  oviparous  animals. 

The  true  difference  in  the  process  of  reproduction,  between  the 
two  classes,  is  therefore  merely  an  apparent,  not  a  fundamental  one. 
In  fish,  reptiles,  and  birds,  the  egg  is  discharged  by  the  female 
before  or  immediately  after  impregnation,  and  the  embryo  subse- 
quently developed  and  hatched  externally.  In  the  quadrupeds  and 
the  human  species,  on  the  other  hand,  the  egg  is  retained  within 
the  body  of  the  female  until  the  embryo  is  developed ;  when  the 
membranes  are  ruptured  and  the  young  expelled  at  the  same  time. 
In  all  classes,  however,  viviparous  as  well  as  oviparous,  the  young 
is  produced  equally  from  an  egg;  and  in  all  classes  the  egg, 
sometimes  larger  and  sometimes  smaller,  but  always  consisting 
essentially  of  a  vitellus  and  a  vitelline  membrane,  is  contained 
originally  in  the  interior  of  an  ovarian  follicle. 

The  egg  is  accordingl}'-,  as  we  have  already  intimated,  an  integral 
part  of  the  ovarian  tissue.  It  may  be  found  there  long  before  the 
generative  function  is  established,  and  during  the  earliest  periods 
of  life.  It  may  be  found  without  difficulty  in  the  newly  bora 
female  infant,  and  may  even  be  detected  in  the  foetus  before  birth. 
Its  growth  and  nutrition,  also,  are  provided  for  in  the  same  man- 
ner with  that  of  other  portions  of  the  bodily  structure. 

2d.  27iese  eggs  become  more  fully  developed  at  a  certain  age,  ichen 
the  generative  function  is  about  to  be  established.  During  the  early 
periods  of  life,  the  ovaries  and  their  contents,  like  many  other 
organs,  are  imperfectly  developed.  They  exist,  but  they  are  as 
yet  inactive,  and  incapable  of  performing  any  function.  In  the 
yo^ng  chick,  for  example,  the  ovary  is  of  small  size ;  and  the  eggs, 
instead  of  presenting  the  voluminous,  yellow,  opaque  vitellus  which 
they  afterward  exhibit,  are  minute,  transparent,  and  colorless.  In 
the  young  quadrupeds,  and  in  the  human  female  during  infancy 
and  childhood,  the  ovaries  are  equally  inactive.  They  are  small, 
friable,  and  of  a  nearly  homogeneous  appearance  to  the  naked  eye ; 
presenting  none  of  the  enlarged  follicles,  filled  with  transparent 
fluid,  which  are  afterward  so  readily  distinguished.  At  this  time, 
accordingly,  the  female  is  incapable  of  bearing  young,  because  the 
ovaries  are  inactive,  and  the  eggs  which  they  contain  immature. 

At  a  certain  period,  however,  which  varies  in  the  time  of  its 


PERIODICAL    OVULATION.  467 

occurrence  for  different  species  of  animals,  the  sexual  apparatus 
begins  to  enter  upon  a  state  of  activity.  The  ovaries  increase  in 
size,  and  their  circulation  becomes  more  active.  The  eggs,  also, 
instead  of  remaining  quiescent,  take  on  a  rapid  growth,  and  the 
structure  of  the  vitellus  is  completed  by  the  abundant  deposit  of 
oleaginous  granules  in  its  interior.  Arrived  at  this  state,  the  eggs 
are  ready  for  impregnation,  and  the  female  becomes  capable  of 
bearing  young.  She  is  then  said  to  have  arrived  at  tl^  state  of 
"  puberty,"  or  that  condition  in  which  the  generative  organs  are 
fully  developed.  This  condition  is  accompanied  by  a  visible 
alteration  in  the  system  at  large,  which  indicates  the  complete 
development  of  the  entire  organism.  In  many  birds,  for  example, 
the  plumage  assumes  at  this  period  more  varied  and  brilliant 
colors;  and  in  the  common  fowl  the  comb,  or  "crest,"  enlarges 
and  becomes  red  and  vascular.  In  the  American  deer  (Cervus 
virginianus),  the  coat,  which  during  the  first  year  is  mottled  with 
white,  becomes  in  the  second  year,  of  a  uniform  tawny  or  reddish 
tinge.  In  nearly  all  species,  the  limbs  become  more  compact  and 
the  body  more  rounded ;  and  the  whole  external  appearance  is  so 
altered,  as  to  indicate  that  the  animal  has  arrived  at  the  period  of 
puberty,  and  is  capable  of  reproduction. 

3d.  Successive  crops  of  eggs^  in  the  adult  female,  ripen  and  are 
discharged  independently  of  sexual  intercourse.  It  was  formerly  sup- 
posed, as  we  have  mentioned  above,  that  in  the  viviparous  animals 
the  germ  was  formed  in  the  body  of  the  female  only  as  a  conse- 
quence of  sexual  intercourse.  Even  after  the  important  fact 
became  known  that  eggs  exist  originally  in  the  ovaries  of  these 
animals,  and  are  only  fecundated  by  the  influence  of  the  sperm- 
atic fluid,  the  opinion  still  prevailed  that  the  occurrence  of  sexual 
intercourse  was  the  cause  of  their  being  discharged  from  the  ovary, 
and  that  the  rupture  of  a  Graafian  vesicle  in  this  organ  was  a 
certain  indication  that  coitus  had  taken  place. 

This  opinion,  however,  was  altogether  unfounded.  We  already 
know  that  in  fish  and  reptiles  the  mature  eggs  not  only  leave  the 
ovary,  but  are  actually  discharged  from  the  body  of  the  female 
while  still  unimpregnated,  and  only  subsequently  come  in  contact 
with  the  spermatic  fluid.  In  fowls,  also,  it  is  a  matter  of  common 
observation  that  the  hen  will  continue  to  lay  fully-formed  eggs,  if 
well  supplied  with  nourishment,  without  the  presence  of  the  cock  ; 
only  these  eggs,  being  unimpregnated,  are  incapable  of  producing 


468        OVULATION    AND    FUNCTION    OF    MENSTRUATION. 

chicks.  In  oviparous  animals,  therefore,  the  discharge  of  the  egg, 
as  well  as  its  formation,  is  independent  of  sexual  intercourse. 

Continued  observation  shows  this  to  be  the  case,  also,  in  the 
viviparous  quadrupeds.  The  researches  of  Bischoff,  Pouchet,  and 
Coste  have  demonstrated  that  in  the  sheep,  the  pig,  the  bitch,  the 
rabbit,  &c.,  if  the  female  be  carefully  kept  from  the  male  until  after 
the  period  of  puberty  is  established,  and  then  killed,  examination 
of  the  q«iries  will  show  that  Graafian  vesicles  have  matured,  rup- 
tured, and  discharged  their  eggs,  in  the  same  manner  as  though 
sexual  intercourse  had  taken  place.  Sometimes  the  vesicles  are 
found  distended  and  prominent  upon  the  surface  of  the  ovary ; 
sometimes  recently  ruptured  and  collapsed;  and  sometimes  in  vari- 
ous stages  of  cicatrization  and  atrophy,  Bischoff','  in  several  in- 
stnnces  of  this  kind,  actually  found  the  unimpregnated  eggs  in  the 
oviduct,  on  their  way  to  the  cavity  of  the  uterus.  In  those  animals 
in  which  the  ripening  of  the  eggs  takes  place  at  short  intervals,  as, 
for  example,  the  sheep,  the  pig,  and  the  cow,  it  is  very  rare  to  exa- 
mine the  ovaries  in  any  instance  where  traces  of  a  more  or  less 
recent  rupture  of  the  Graafian  follicles  are  not  distinctly  visible. 

One  of  the  most  important  facts,  derived  from  the  examination 
of  such  cases  as  the  above,  is  that  the  ovarian  eggs  become  deve- 
loped and  are  discharged  in  successive  crops,  which  follow  each 
other  regularly  at  periodical  intervals.  If  we  examine  the  ovary 
of  the  fowl,  for  example  (Fig.  163),  we  see  at  a  glance  how  the  eggs 
grow  and  ripen,  one  after  tlie  other,  like  fruit  upon  a  vine.  In  this 
instance,  the  process  of  evolution  is  very  rapid ;  and  it  is  easy  to 
distinguish,  at  the  same  time,  eggs  which  are  almost  microscopic  in 
size,  colorless,  and  transparent;  those  which  are  larger,  firmer, 
somewhat  opaline,  and  yellowish  in  hue ;  and  finally  those  which 
are  fully  developed,  opaque,  of  a  deep  orange  color,  and  just  ready 
to  leave  the  ovary. 

It  will  be  observed  that  in  this  instance  the  difference  between 
the  undeveloped  and  mature  eggs  consists  principally  in  the  size  of 
the  vitellus,  which  is  furthermore,  for  reasons  previously  given 
(Chap.  III.),  very  much  larger  than  in  the  quadrupeds.  It  is  also 
seen  that  it  is  the  increased  size  of  the  vitellus  alone,  by  which  the 
ovarian  follicle  is  distended  and  ruptured,  and  the  egg  finally  dis- 
charged. 

In  the  human  species  and  the  quadrupeds,  on  the  other  hand, 

'  Memoire  sur  la  cliute  perioflique  de  I'oeuf,  &c.,  Annales  fles  Sciences  Naturelles, 
Aoiit — Septembre,  1844. 


PERIODICAL    OVULATION".  469 

the  microscopic  egg  never  becomes  large  enough  to  distend  the 
follicle  by  its  own  size.  The  rupture  of  the  follicle  and  the  libera- 
tion of  the  egg  are  accordingly  provided  for,  in  these  instances,  by 
a  totally  different  mechanism. 

In  the  earlier  periods  of  life,  in  man  and  the  higher  animals,  the 
egg  is  contained  in  a  Graafian  follicle  which  closely  embraces  its 
exterior,  and  is  consequently  hardly  larger  than  the  egg  itself.  As 
puberty  approaches,  those  follicles  which  are  situated  near  the  free 
surface  of  the  ovary  become  enlarged  by  the  accumulation  of  a 
colorless  serous  fluid  in  their  cavity.  We  then  find  that  the  ovary, 
when  cut  open,  shows  a  considerable  number  of  globular,  transpa- 
rent vesicles,  readily  perceptible  by  the  eye,  the  smaller  of  which 
are  deep  seated,  but  which  increase  in  size  as  they  approach  the 
free  surface  of  the  organ.  These  vesicles  are  the  Graafian  follicles, 
which,  in  consequence  of  the  advancing  maturity  of  the  eggs  con- 
tained in  them,  gradually  enlarge  as  the  period  of  generation  ap- 
proaches. 

The  Graafian  follicle  at  this  time  consists  of  a  closed  globular 
sac  or  vesicle,  the  external  wall  of  which,  though  quite  translucent, 
has  a  fibrous  texture  under  the  microscope  and  is  well  supplied 
with  bloodvessels.  This  fibrous  and  vascular  wall  is  distinguished 
by  the  name  of  the  "  membrane  of  the  vesicle."  It  is  not  very 
firm  in  texture,  and  if  roughly  handled  is  easily  ruptured. 

The  membrane  of  the  vesicle  is  lined  throughout  by  a  thin  layer 
of  minute  granular  cells,  which  form  for  it  a  kind  of  epithelium, 
similar  to  the  epithelium  of  the  pleura,  pericardium,  and  other 
serous  membranes.  This  layer  is  termed  the  membrana  granulosa. 
It  adheres  but  slightly  to  the  membrane  of  the  vesicle,  and  may 
easily  be  detached  by  careless  manipulation  before  the  vesicle  is 
opened,  being  then  mingled,  in  the  form  of  light  flakes  and  shreds, 
with  the  serous  fluid  contained  in  the  vesicle. 

At  the  most  superficial  part  of  the  Graafian  follicle,  or  that 
which  is  nearest  the  surface  of  the  ovary,  the  membrana  granulosa 
is  thicker  than  elsewhere.  Its  cells  are  here  accumulated,  in  a 
kind  of  mound  or  "heap,"  which  has  received  the  name  of  the 
cumulus  proligervs.  It  is  sometimes  called  the  discus  proligerus^ 
because  the  thickened  mass,  when  viewed  from  above,  has  a  some- 
what circular  or  disk-like  form.  In  the  centre  of  this  thickened 
portion  of  the  membrana  granulosa  the  egg  is  imbedded.  It  is 
accordingly  always  situated  at  the  most  superficial  portion  of  the 
follicle,  and  advances  in  this  way  toward  the  surface  of  the  ovary. 


470        OVULATION    AND    FUNCTION    OF    MENSTRUATION. 

As  the  period  approaches  at  which  the  egg  is  destined  to  be  dis- 
charged, the  Graafian  follicle  becomes  more  vascular,  and  enlarges 
by  an  increased  exudation  of  serum  into  its  cavity.     It  then  begins 


Fig.  168. 


Graafian  Follicle,  near  the  period  of  rupture. — a.  Membrane  of  the  vesicle.  6.  Membrana 
granulosa,  c.  Cavity  of  follicle,  d.  Egg.  e.  Peritoneum.  /.  Tunica  albuginea.  g,  g.  Tissue  of 
llie  ovary. 

to  project  from  the  surface  of  the  ovary,  still  covered  by  the  albu- 
gineous  tunic  and  the  peritoneum,  (Fig.  168.)  The  constant  accu- 
mulation of  fluid,  however,  in  the  follicle,  exerts  such  a  steady  and 
increasing  pressure  from  within  outward,  that  the  albugineous  tunic 
and  the  peritoneum  successively  yield  before  it;  until  the  Graafian 
follicle  protrudes  from  the  ovary  as  a  tense,  rounded,  translucent 
vesicle,  in  which  the  sense  of  fluctuation  can  be  readily  perceived 
on  applying  the  fingers  to  its  surface.  Finally,  the  process  of  effu- 
sion and  distension  still  going  on,  the  wall  of  the  vesicle  yields  at 
its  most  prominent  portion,  the  contained  fluid  is  driven  out  with  a 
o'ush,  by  the  reaction  and  elasticity  of  the  neighboring  ovarian 

tissues,  carrying  with  it  the  egg^ 
still  entangled  in  the  cells  of  the 
proligerous  disc. 

The  rupture  of  the  Graafian 
vesicle  is  accompanied,  in  some 
instances,  by  an  abundant  hemor- 
rhage, which  takes  place  from  the 
internal  surface  of  the  congested 
follicle,  and  by  which  its  cavity 
is  filled  with  blood.  This  occurs 
in  the  human  subject  and  in  the 
pig,  and  to  a  certain  extent,  also, 
in  other  of  the  lower  animals. 
Sometimes,  as  in  the  cow,  where 


Fig.  169, 


Ovary  with  Graafian  Follicle 
kdptured;  at  a, egg  just  discluirged  with  a 
portion  of  membraua  granulosa. 


PERIODICAL    OVULATION.  471 

iio  hemorrhage  takes  place,  the  Graafian  vesicle  when  ruptured 
simply  collapses;  after  which,  a  slight  exudation,  more  or  less  tinged 
with  blood,  is  poured  out  during  the  course  of  a  few  hours. 

Notwithstanding,  however,  these  slight  variations,  the  expulsion 
of  the  egg  takes  place,  in  the  higher  animals,  always  in  the  manner 
above  described,  viz.,  bj  the  accumulation  of  serous  fluid  in  the 
cavity  of  the  Graafian  follicle,  by  which  its  walls  are  gradually  dis- 
tended and  finally  ruptured. 

This  process  takes  place  in  one  or  more  Graafian  follicles  at  a 
time,  according  to  the  number  of  young  which  the  animal  produces 
at  a  birth.  In  the  bitch  and  the  sow,  where  each  litter  consists  of 
from  six  to  twenty  young  ones,  a  similar  number  of  eggs  ripen  and 
are  discharged  at  each  period.  In  the  mare,  the  cow,  and  in  the 
iiuman  female,  where  there  is  usually  but  one  foetus  brought  forth 
at  a  birth,  the  eggs  are  matured  singly,  and  the  Graafian  vesicles 
luptured,  one  after  another,  at  successive  periods  of  ovulation. 

4th.  The  ripening  and  discharge  of  the  egg  are  accompanied  by  a  pecu- 
liar condition  of  the  entire  system^  known  as  the  "  rutting''''  condition^  or 
'■'' (xstruationr  The  peculiar  congestion  and  functional  activity  of 
the  ovaries  at  each  period  of  ovulation,  act  by  sympathy  upon  the 
other  generative  organs,  and  produce  in  them  a  greater  or  less  de- 
gree of  excitement,  according  to  the  particular  species  of  animal. 
Almost  always  there  is  a  certain  amount  of  congestion  of  the  entire 
generative  apparatus ;  Fallopian  tubes,  uterus,  vagina,  and  external 
organs.  The  secretions  of  the  vagina  and  neighboring  parts  are 
more  particularly  affected,  being  usually  increased  in  quantity  and 
at  the  same  time  altered  in  quality.  In  the  bitch,  the  vaginal  raur 
cous  membrane  becomes  red  and  tumefied,  and  pours  out  an  abun- 
dant secretion  which  is  often  more  or  less  tinged  with  blood.  The 
secretions  acquire  also  at  this  time  a  peculiar  odor,  which  ap- 
]iears  to  attract  the  male,  and  to  excite  in  him  the  sexual  impulse. 
An  unusual  tumefaction  and  redness  of  the  vagina  and  vulva  are 
also  very  perceptible  in  the  rabbit ;  and  in  some  species  of  apes  it 
has  been  observed  that  these  periods  are  accompanied  not  only  by 
a  bloody  discharge  from  the  vulva,  but  also  by  an  engorgement  and 
infiltration  of  the  neighboring  parts,  extending  even  to  the  skin  of 
the  buttocks,  the  thighs,  and  the  under  part  of  the  tail.^ 

The  system  at  large  is  also  visibly  affected  by  the  process  going 
on  in   the  ovary.     In  the  cow,  for  example,  the  approach  of  an 

'  Pouchet,  Tlieorie  positive  de  I'ovulation,  &c.     Paris,  1847,  p.  230. 


472        OVULATION    AND    FUNCTION    OF    MENSTRUATION. 

oestrual  period  is  marked  by  an  unusual  restlessness  and  agitation, 
easily  recognized  by  an  ordinary  observer.  The  animal  partially 
loses  her  appetite.  She  frequently  stops  browsing,  looks  about  un- 
easily, perhaps  runs  from  one  side  of  the  field  to  the  other,  and  then 
recommences  feeding,  to  be  disturbed  again  in  a  similar  manner 
after  a  short  interval.  Her  motions  are  rapid  and  nervous,  and  her 
hide  often  rough  and  disordered ;  and  the  whole  aspect  of  the  ani- 
mal indicates  the  presence  of  some  unusual  excitement.  After  this 
condition  is  fully  established,  the  vaginal  secretions  show  them- 
selves in  unusual  abundance,  and  so  continue  for  one  or  two  days; 
after  which  the  symptoms,  both  local  and  general,  subside  sponta- 
neously, and  the  animal  returns  to  her  usual  condition. 

It  is  a  remarkable  fact,  in  this  connection,  that  the  female  of 
these  animals  will  allow  the  approaches  of  the  male  only  during  and 
immediately  after  the  oestrual  period ;  that  is,  just  when  the  egg  is 
recently  discharged  and  ready  for  impregnation.  At  other  times, 
when  sexual  intercourse  would  be  necessarily  fruitless,  the  instinct 
of  the  animal  leads  her  to  avoid  it ;  and  the  concourse  of  the  sexes 
is  accordingly  made  to  correspond  in  time  with  the  maturity  of  the 
egg  and  its  aptitude  for  fecundation. 


II,   MENSTRUATION. 

In  the  human  female,  the  return  of  the  periods  of  ovulation  is 
marked  by  a  peculiar  group  of  phenomena  which  are  known  as 
menstruation,  and  which  are  of  sufficient  importance  to  be  described 
by  themselves. 

During  infancy  and  childhood  the  sexual  system,  as  we  have 
mentioned  above,  is  inactive.  No  discharge  of  eggs  takes  place 
from  the  ovaries,  and  no  external  phenomena  show  themselves, 
connected  with  the  reproductive  function. 

At  the  age  of  fourteen  or  fifteen  years,  however,  a  change  begins 
to  manifest  itself.  The  limbs  become  rounder,  the  breasts  increase 
in  size,  and  the  entire  aspect  undergoes  a  peculiar  alteration,  which 
indicates  the  approaching  condition  of  maturity.  At  the  same 
time  a  discharge  of  blood  takes  place  from  the  generative  passages, 
accompanied  by  some  disturbance  of  the  general  system,  and  the 
female  is  then  known  to  have  arrived  at  the  period  of  puberty. 

Afterward,  the  bloody  discharge  just  spoken  of  returns  at  regular 


MENSTRUATION.  473 

intervals  of  four  weeks;  and,  on  account  of  this  recurrence  corres- 
ponding with  the  passage  of  successive  lunar  months,  its  phenomena 
are  designated  by  the  name  of  the  "menses"  or  the  "menstrual 
periods."  The  menses  return  with  regularity,  from  the  time  of 
their  first  appearance,  until  the  age  of  about  forty-five  years. 
During  this  period,  the  female  is  capable  of  bearing  children,  and 
sexual  intercourse  is  liable  to  be  followed  by  pregnancy.  After 
the  forty-fifth  year,  the  periods  first  become  irregular,  and  then 
cease  altogether;  and  their  final  disappearance  is  an  indication  that 
the  woman  is  no  longer  fertile,  and  that  pregnancy  cannot  again 
take  place. 

Even  during  the  period  above  referred  to,  from  the  age  of  fifteen 
to  forty-five,  the  regularity  and  completeness  of  the  menstrual 
periods  indicate  to  a  great  extent  the  aptitude  of  individual  females 
for  impregnation.  It  is  well  known  that  all  those  causes  of  ill 
health  which  derange  menstruation  are  apt  at  the  same  time  to 
interfere  with  pregnancy  ;  so  that  women  whose  menses  are  habi- 
tually regular  and  natural  are  much  more  likely  to  become  preg- 
nant, after  sexual  intercourse,  than  those  in  whom  the  periods  are 
absent  or  irregular. 

If  pregnancy  happen  to  take  place,  however,  at  any  time  during 
the  child-bearing  period,  the  menses  are  suspended  during  the  con- 
tinuance of  gestation,  and  usually  remain  absent  after  delivery,  as 
long  as  the  woman  continues  to  nurse  her  child.  They  then  re- 
commence, and  subsequently  continue  to  appear  as  before. 

The  menstrual  discharge  consists  of  an  abundant  secretion  of 
mucus  mingled  with  blood.  When  the  expected  period  is  about 
to  come  on,  the  female  is  affected  with  a  certain  degree  of  discomfort 
and  lassitude,  a  sense  of  weight  in  the  pelvis,  and  more  or  less  dis- 
inclination to  society.  These  symptoms  are  in  some  instances 
slightly  pronounced,  in  others  more  troublesome.  An  unusual 
discharge  of  vaginal  mucus  then  begins  to  take  place,  which  soon 
becomes  yellowish  or  rusty  brown  in  color,  from  the  admixture  of 
a  certain  proportion  of  blood;  and  by  the  second  or  third  day  the 
discharge  has  the  appearance  of  nearly  pure  blood.  The  unpleasant 
sensations  which  were  at  first  manifest  then  usually  subside ;  and 
the  discharge,  after  continuing  for  a  certain  period,  begins  to  grow 
more  scanty.  Its  color  changes  from  a  pure  red  to  a  brownish  or 
rusty  tinge,  until  it  finally  disappears  altogether,  and  the  female 
returns  to  her  ordinary  condition. 

The  menstrual  epochs  of  the  human  female  correspond  with  the 


474        OVULATION    AND    FUNCTION    OF    MENSTEUATION. 

periods  of  oestruation  in  the  lower  animals.  Their  general  resem- 
blance to  these  periods  is  too  evident  to  require  demonstration. 
Like  them,  they  are  absent  in  the  immature  female ;  and  begin 
to  take  place  only  at  the  period  of  puberty,  when  the  aptitude 
for  impregnation  first  commences.  Like  them,  they  recur  during 
the  child-bearing  period  at  regular  intervals ;  and  are  liable  to  the 
same  interruption  bj'  pregnancy  and  lactation.  Finally,  their  dis- 
appearance corresponds  with  the  cessation  of  fertility. 

The  periods  of  oestruation,  furthermore,  in  many  of  the  lower 
animals,  are  accompanied,  as  we  have  already  seen,  with  an  unusual 
discharge  from  the  generative  passages;  and  this  discharge  is  fre- 
quently more  or  less  tinged  with  blood.  In  the  human  female  the 
bloody  discharge  is  more  abundant  than  in  other  instances,  but  it  is 
evidently  a  phenomenon  differing  only  in  degree  from  that  which 
shows  itself  in  many  species  of  animals. 

The  most  complete  evidence,  however,  that  the  period  of  men- 
struation is  in  realitv  that  of  ovulation,  is  derived  from  the  results 
of  direct  observation.  A  sufficient  number  of  instances  have  now 
been  observed  to  show  that  at  the  menstrual  epoch  a  Graafian 
vesicle  becomes  enlarged,  ruptures,  and  discharges  its  egg.  Cruik- 
shank*  noticed  such  a  case  so  long  ago  as  1797.  Negrier^  relates 
two  instances,  communicated  to  him  by  Dr.  Ollivier  d' Angers,  in 
which,  after  sudden  death  during  menstruation,  a  bloody  and  rup- 
tured Graafian  vesicle  was  found  in  the  ovary.  Bischoff^  speaks  of 
four  similar  cases  in  his  own  observation,  in  three  of  which  the 
vesicle  was  just  raptured,  and  in  the  fourth  distended,  prominent, 
and  ready  to  burst.  Coste^  has  met  with  several  of  the  same  kind. 
Dr.  Michel*  found  a  vesicle  ruptured  and  filled  with  blood  in  a 
woman  who  was  executed  for  murder  while  the  menses  were  pre- 
sent. We  have  also^  met  with  the  same  appearances  in  a  case  of 
death  from  acute  disease,  on  the  second  day  of  menstruation. 

The  process  of  ovulation,  accordingly,  in  the  human  female, 
accompanies  and  forms  a  part  of  that  of  menstruation.  As  the 
menstrual  period  comes  on,  a  congestion  takes  place  in  nearly  the 

'  London  Philosophical  Transactions,  1797,  p.  135. 

^  Recherches  sur  les  Ovaires,  Paris,  1840,  p.  78. 

'*  Annales  des  Sciences  Naturelles,  August,  1844. 

''  Histoire  du  Developpement  des  Corps  Organises,  Paris,  1847,  vol  i.  p.  221. 

5  Am.  .Tourn.  Med.  Sci.,  July,  1848. 

^  Corpus  Luteum  of  Menstruation  and  Pregnancy,  in  Transactions  of  American 
Medical  Association,  Philadelphia,  1851. 


MENSTRUATION.  475 

whole  of  the  generative  apparatus;  in  the  Fallopian  tubes  and  the 
uterus,  as  well  as  in  the  ovaries  and  their  contents.  One  of  the 
Graafian  follicles  is  more  especially  the  seat  of  an  unusual  vascular 
excitement.  It  becomes  distended  by  the  fluid  which  accumulates 
in  its  cavity,  projects  from  the  surface  of  the  ovary,  and  is  finally 
ruptured,  in  the  same  manner  as  we  have  already  described  this 
process  taking  place  in  the  lower  animals. 

It  is  not  quite  certain  at  what  particular  period  of  the  menstrual 
flow  the  rupture  of  the  vesicle  and  discharge  of  the  egg  take  place. 
It  is  the  opinion  of  Bischoflf,  Pouchet,  and  Kaciborski,  that  the 
regular  time  for  this  rupture  and  discharge  is  not  at  the  commence- 
ment, but  towards  the  termination  of  the  period.  Coste'  has  ascer- 
tained, from  his  observations,  that  the  vesicle  ruptures  sometimes 
in  the  early  part  of  the  menstrual  epoch,  and  sometimes  later.  So 
far  as  we  can  learn,  therefore,  the  precise  period  of  the  discharge 
of  the  egg  is  not  invariable.  Like  the  menses  themselves,  it  may 
take  place  apparently  a  little  earlier  or  a  little  later,  according  to 
various  accidental  circumstances;  but  it  always  occurs  at  some 
time  in  connection  with  the  menstrual  flow,  and  constitutes  the 
most  essential  and  important  part  of  the  catamenial  process. 

The  egg,  when  discharged  from  the  ovary,  enters  the  fimbriated 
extremity  of  the  Fallopian  tube,  and  commences  its  passage  toward 
the  uterus.  The  mechanism  by  which  it  finds  its  way  into  and  through 
the  Fallopian  tube  is  different,  in  the  quadrupeds  and  the  human 
species,  and  in  birds  and  reptiles.  In  the  latter,  the  bulk  of  the  egg 
or  mass  of  eggs  discharged  is  so  great  as  to  fill  entirely  the  wide 
extremity  of  the  oviduct,  and  they  are  afterward  conveyed  down- 
ward by  the  peristaltic  action  of  the  muscular  coat  of  this  canal. 
In  the  higher  classes,  on  the  contrary,  the  egg  is  microscopic  in 
size,  and  would  be  liable  to  be  lost,  were  there  not  some  further 
provision  for  its  safety.  The  wide  extremity  of  the  Fallopian  tube, 
accordingly,  which  is  here  directed  toward  the  ovary,  is  lined  with 
ciliated  epithelium ;  and  the  movement  of  the  cilia,  which  is 
directed  from  the  ovary  toward  the  uterus,  produces  a  kind  of  con- 
verging stream,  or  vortex,  by  which  the  egg  is  necessarily  drawn 
toward  the  narrow  portion  of  the  tube,  and  subsequently  conducted 
to  the  cavity  of  the  uterus. 

Accidental  causes,  however,  sometimes  disturb  this  regular  course 
or  passage  of  the  egg.     The  egg  may  be  arrested,  for  example, 

'  Loc   cit. 


476        OVULATION    AND    FUNCTION    OF    MENSTRUATION. 

at  the  surfiice  of  the  ovary,  and  so  fail  to  enter  the  tube  at  all. 
If  fecundated  in  this  situation,  it  will  then  give  rise  to  "ovarian 
pregnancy."  It  may  escape  from  the  fimbriated  extremity  into  the 
peritoneal  cavity,  and  form  attachments  to  some  one  of  the  neigh- 
boring organs,  causing  "abdominal  pregnancy;"  or  finally,  it  may 
stop  at  any  part  of  the  Fallopian  tube,  and  so  give  origin  to  "tubal 
pregnancy." 

The  egg,  immediately  upon  its  discharge  from  the  ovary,  is  ready 
for  impregnation.  If  sexual  intercourse  happen  to  take  place  about 
that  time,  the  egg  and  the  spermatic  fluid  meet  in  some  part  of  the 
female  generative  passages,  and  fecundation  is  accomplished.  It 
appears,  from  various  observations  of  Bischoff,  Coste,  and  others, 
that  this  contact  may  take  place  between  the  egg  and  the  sperm, 
either  in  the  uterus  or  any  part  of  the  Fallopian  tubes,  or  even 
upon  the  surface  of  the  ovary.  If,  on  the  other  hand,  coitus  do  not 
take  place,  the  egg  passes  down  to  the  uterus  unimpregnated,  loses 
its  vitality  after  a  short  time,  and  is  finally  carried  away  with  the 
uterine  secretions. 

It  is  easily  understood,  therefore,  why  sexual  intercourse  should 
be  more  liable  to  be  followed  by  pregnancy  when  it  occurs  about 
the  menstrual  epoch  than  at  other  times.  This  fact,  which  was  long 
since  established  as  a  matter  of  observation  by  practical  obstetri- 
cians, depends  simply  upon  the  coincidence  in  time  between  men- 
struation and  the  discharge  of  the  egg.  Before  its  discharge,  the 
egg  is  immature,  and  unprepared  for  impregnation ;  and  after  the 
menstrual  period  has  passed,  it  gradually  loses  its  freshness  and 
vitality.  The  exact  length  of  time,  however,  preceding  and  follow- 
ing the  menses,  during  which  impregnation  is  still  possible,  has  not 
been  ascertained.  The  spermatic  fluid,  on  the  one  hand,  retains  its 
vitality  for  an  unknown  period  after  coition,  and  the  egg  for  an 
unknown  period  after  its  discharge.  Both  these  occurrences  may, 
therefore,  either  precede  or  follow  each  other  within  certain  limits, 
and  impregnation  be  still  possible ;  but  the  precise  extent  of  these 
limits  is  still  uncertain,  and  is  probably  more  or  less  variable  in 
diffent  individuals. 

The  above  facts  indicate  also  the  true  explanation  of  certain 
exceptional  cases,  which  have  sometimes  been  observed,  in  which 
fertility  exists  without  menstruation.  Various  authors  (Churchill, 
Reid,  Velpeau,  &c.)  have  related  instances  of  fruitful  women  in  whom 
the  menses  were  very  scanty  and  irregular,  or  even  entirely  absent. 
The  menstrual  flow  is,  in  fact,  only  the  external  sign  and  accompa- 


MENSTRUATION".  477 

niment  of  a  more  important  process  taking  place  within.  It  is 
habitual]}''  scanty  in  some  individuals,  and  abundant  in  others. 
Such  variations  depend  upon  the  condition  of  vascular  activity  of 
the  system  at  large,  or  of  the  uterine  organs  in  particular;  and 
though  the  bloody  discharge  is  usually  an  index  of  the  general 
aptitude  of  these  organs  for  successful  impregnation,  it  is  not  an 
absolute  or  necessary  requisite.  Provided  a  mature  egg  be  dis- 
charged from  the  ovary  at  the  appointed  period,  menstruation  pro- 
perly speaking  exists,  and  pregnancy  is  possible. 

The  blood  which  escapes  during  the  menstrual  flow  is  supplied 
by  the  uterine  mucous  membrane.  If  the  cavity  of  the  uterus  be 
examined  after  death  during  menstruation,  its  internal  surface  is 
seen  to  be  smeared  with  a  thickish  bloody  fluid,  which  may  be 
traced  through  the  uterine  cervix  and  into  the  vagina.  The  Fallo- 
pian tubes  themselves  are  sometimes  found  excessively  congested, 
and  filled  with  a  similar  bloody  discharge.  The  menstrual  blood 
has  also  been  seen  to  exude  from  the  uterine  orifice  in  cases  of  pro- 
cidentia uteri,  as  well  as  in  the  natural  condition  by  examination 
■with  the  vaginal  speculum.  It  is  discharged  by  a  kind  of  capillary 
hemorrhage,  similar  to  that  which  takes  place  from  the  lungs  in 
cases  of  hemoptysis,  only  less  sudden  and  violent.  The  blood  does 
not  form  any  visible  coagulum,  owing  to  its  being  gradually  exuded 
from  many  minute  points,  and  mingled  with  a  large  quantity  of 
mucus.  When  poured  out,  however,  more  rapidly  or  in  larger 
quantity  than  usual,  as  in  cases  of  menorrhagia,  the  menstrual  blood 
coagulates  in  the  same  manner  as  if  derived  from  any  other  source. 
The  hemorrhage  which  supplies  it  comes  from  the  whole  extent  of 
the  mucous  membrane  of  the  body  of  the  uterus,  and  is,  at  the  same 
time,  the  consequence  and  the  natural  termination  of  the  periodical 
congestion  of  the  parts. 


478  MENSTRUATION    AND    PREGNANCY. 


CHAPTER   VI. 

ON  THE  CORPUS  LUTEUM  OF  MENSTRUATION  AND 

PREGNANCY. 

After  the  rupture  of  the  Graafian  vesicle  at  the  menstrual 
period,  a  bloody  cavity  is  left  in  the  ovary  which  is  subsequently 
obliterated  by  a  kind  of  granulating  process,  somewhat  similar  in 
character  to  the  healing  of  an  abscess.  For  the  Graafian  vesicle 
is  intended  simply  for  the  formation  and  growth  of  the  egg. 
After  the  egg  therefore  has  arrived  at  maturity  and  has  been  dis- 
charged, the  Graafian  follicle  has  no  longer  any  function  to  per- 
form. It  then  only  remains  for  it  to  pass  through  a  process  of 
obliteration  and  atrophy,  as  an  organ  which  has  become  useless 
and  obsolete.  While  undergoing  this  process,  the  Graafian  vesicle 
is  at  one  time  converted  into  a  peculiar,  solid,  globular  body,  which 
is  called  the  corpus  luteum ;  a  name  given  to  it  on  account  of  the 
yellow  color  which  it  acquires  at  a  certain  period  of  its  formation. 

We  shall  proceed  to  describe  the  corpus  luteum  in  the  human 
species;  first,  as  it  follows  the  ordinary  course  of  development 
after  menstruation ;  and  secondly,  as  it  is  modified  in  its  growth 
and  appearance  during  the  existence  of  pregnancy. 


I.  CORPUS  luteum  of  menstruation. 

We  have  already  described,  in  the  preceding  chapter,  the  man- 
ner in  which  a  Graafian  vesicle,  at  each  menstrual  epoch,  swells, 
protrudes  from  the  surface  of  the  ovary,  and  at  last  ruptures  and 
discharges  its  egg.  At  the  moment  of  rupture,  or  immediately 
after  it,  an  abundant  hemorrhage  takes  place  in  the  human  sub- 
ject from  the  vessels  of  the  follicle,  by  which  its  cavity  is  filled 
with  blood.  This  blood  coagulates  soon  after  its  exudation,  as 
it  would  do  if  extravasated  in  any  other  part  of  the  body,  and 
the  coagulum  is  retained  in  the  interior  of  the  Graafian  follicle. 


CORPUS  LUTEUM  OF  MENSTRUATION. 


479 


&  -  h 


Graafian  Follicle 
receully  ruplured  during 
nienstniation,  and  filled 
with  a  bloody  coaguliim  ; 
shown  in  longitudinal  sec- 
tion.— a.  Tissue  of  the 
ovary,  b.  Membrane  of  the 
vesicle,    c.  Point  of  rupture. 


The  opening  by  which  the  Qgg  makes  its  escape  is  usually  not  an 
extensive  laceration,  but  a  minute  rounded  perforation,  often  not 
more  than  half  a  line  in  diameter.  A  small  probe,  introduced 
through  this  opening,  passes  directly  into  the 
cavity  of  the  follicle.  If  the  Graafian  follicle 
be  opened  at  this  time  by  a  longitudinal  inci- 
sion (Fig.  170),  it  will  be  seen  to  form  a  globu- 
lar cavity,  one-half  to  three-quarters  of  an 
inch  in  diameter,  containing  a  soft,  recent, 
dark  colored  coagulum.  This  coagulum  has 
no  organic  connection  with  the  walls  of  the 
follicle,  but  lies  loose  in  its  cavity  and  may  be 
easily  turned  out  with  the  handle  of  a  knife. 
There  is  sometimes  a  slight  mechanical  adhe- 
sion of  the  clot  to  the  eds^es  of  the  lacerated 
opening,  just  as  the  coagulum  in  a  recently 
ligatured  artery  is  entangled  by  the  divided 
edges  of  the  internal  and  middle  coats;  but 
there  is  no  continuity  of  substance  between 
them,  and  the  clot  may  be  everywhere  readily 
separated  by  careful  manipulation.  The  membrane  of  the  vesicle 
presents  at  this  time  a  smooth,  transparent,  and  vascular  internal 
surface,  without  any  alteration  of  color,  consistency,  or  texture. 

An  important  change,  however,  soon  begins  to  take  place,  both 
in  the  central  coagulum  and  in  the  membrane  of  the  vesicle. 

The  clot,  which  is  at  first  large,  soft,  and  gelatinous,  like  any 
other  mass  of  coagulated  blood,  begins  to  contract;  and  the  serum 
separates  from  the  coagulum  proper.  The  serum,  as  fast  as  it 
separates  from  the  coagulum,  is  absorbed  by  the  neighboring  parts; 
and  the  clot,  accordingly,  grows  every  day  smaller  and  denser  than 
before.  At  the  same  time  the  coloring  matter  of  the  blood  under- 
goes the  changes  which  usually  take  place  in  it  after  extravasation, 
and  is  partially  reabsorbed  together  with  the  serum.  This  second 
change  is  somewhat  less  rapid  than  the  former,  but  still  a  diminu- 
tion of  color  is  very  perceptible  in  the  clot,  at  the  expiration  of  two 
weeks. 

The  membrane  of  the  vesicle  during  this  time  is  beginning  to 
undergo  a  process  of  hypertrophy  or  development,  by  which  it 
becomes  thickened  and  convoluted,  and  tends  to  fill  up  partially 
the  cavity  of  the  follicle.  This  hypertrophy  and  convolution  of 
the  membrane  just  named  commences  and  proceeds  most  rapidly 


480 


MENSTRUATION    AND    PREGNANCY. 


Fig.  171. 


at  the  deeper  part  of  the  follicle,  directly  opposite  the  situation  of 
the  superficial  rupture.  From  this  point  it  gradually  becomes 
thinner  and  less  convoluted  as  it  approaches  the  surface  of  the 
ovary  and  the  edges  of  the  ruptured  orifice. 

At  the  end  of  three  weeks,  this  hypertrophy  of  the  membrane  of 
the  vesicle  has  reached  its  maximum.  The  ruptured  Graafian  fol- 
licle has  now  become  so  completely  solidified  by  the  new  growth 
above  described,  and  by  the  condensation  of  its  clot,  that  it  receives 
the  name  of  the  corpus  luteum.  It  forms  a  perceptible  prominence 
upon  the  surface  of  the  ovary,  and  may  be  felt  between  the  fingers 
as  a  well-defined  rounded  tumor,  which  is  nearly  always  somewhat 
flattened  from  side  to  side.     It  measures  about  three-quarters  of  an 

inch  in  length  and  half  an  inch  in 
depth.  On  its  surface  may  be  seen  a 
minute  cicatrix  of  the  peritoneum, 
occupying  the  spot  of  the  original 
rupture. 

On  cutting  it  open  at  this  time  (Fig. 
171),  the  corpus  luteum  is  seen  to  con- 
sist, as  above  described,  of  a  central 
coagulum  and  a  convoluted  wall. 
The  coagulum  is  semi-transparent,  of 
a  gray  or  light  greenish  color,  more 
or  less  mottled  with  red.  The  con- 
voluted wall  is  about  one-eighth  of 
an  inch  thick  at  its  deepest  part,  and 
of  an  indefinite  yellowish  or  rosy 
hue,  not  very  different  in  tinge  from 
the  rest  of  the  ovarian  tissue.  The  convoluted  wall  and  the  con- 
tained clot  lie  simply  in  contact  with  each  other,  as  at  first,  without 
any  intervening  membrane  or  other  organic  connection ;  and  they 
may  still  be  readily  separated  from  each  other  by  the  handle  of  a 
knife  or  the  flattened  end  of  a  probe.  The  corpus  luteum  at  this 
time  may  also  be  stripped  out,  or  enucleated  entire,  from  the  ovarian 
tissue,  just  as  might  have  been  done  with  the  Graafian  follicle  pre- 
viously to  its  rupture.  When  enucleated  in  this  way,  the  corpus 
luteum  presents  itself  under  the  form  of  a  solid  globular  or  flat- 
tened tumor,  with  convolutions  upon  it  somewhat  similar  in  ap- 
pearance to  those  of  the  brain,  and  covered  with  the  remains  of 
the  areolar  tissue,  by  which  it  was  previously  connected  with  the 
substance  of  the  ovary.  .  . 


Ovary  cut  open,  showing  corpus 
luteum  divided  longitudinally;  three 
weeks  after  menstruation.  From  a  girl 
dead  of  hsemoptysis. 


COEPUS  LUTEUM  OF  MENSTRUATION. 


481 


Fig.  172. 


Ovary,  showing  corpus 
luteum  four  weeks  after  men- 
struation ;  from  a  woman  dead 
of  apoplexy. 


After  the  third  week  from  the  close  of  menstruation,  the  corpus 
luteum  passes  into  a  retrograde  condition.  It  diminishes  percep- 
tibly in  size,  and  the  central  coagulum  continues  to  be  absorbed 
and  loses  still  farther  its  coloring  matter.  The  whole  body  under- 
goes a  process  of  partial  atrophy ;  and  at 
the  end  of  the  fourth  week  it  is  not  more 
than  three-eighths  of  an  inch  in  its  longest 
diameter.  (Fig.  172.)  The  external  cicatrix 
may  still  usually  be  seea,  as  well  as  the 
point  where  the  central  coagulum  comes 
in  contact  with  the  peritoneum.  There 
is  still  no  organic  connection  between  the 
central  coagulum  and  the  convoluted  wall ; 
but  the  partial  condensation  of  the  clot  and 
the  continued  folding  of  the  wall  prevent  the 
separation  of  the  two  being  so  easily  accom- 
plished as  before,  though  it  may  still  be 
eflfected  by  careful  management.  The  entire 
corpus  luteum  may  also  still  be  extracted 
from  its  bed  in  the  ovarian  tissue. 

The  color  of  the  convoluted  wall,  during  the  early  part  of  this 
retrograde  stage,  instead  of  fading,  like  that  of  the  fibrinous  coagu- 
lum, becomes  more  strongly  marked.  From  having  a  dull  yellowish 
or  rosy  hue,  as  at  first,  it  gradually  assumes  a  brighter  and  more 
decided  yellow.  This  change  of  color  in  the  convoluted  wall  is 
produced  in  consequence  of  a  kind  of  fatty  degeneration  which 
takes  place  in  its  texture ;  a  large  quantity  of  oil-globules  being 
deposited  in  it  at  this  time,  as  may  be  readily  recognized  under 
the  microscope.  At  the  end  of  the  fourth 
week,  this  alteration  in  hue  is  complete ; 
and  the  outer  wall  of  the  corpus  luteum 
is  then  of  a  clear  chrome-yellow  color,  by 
which  it  is  readily  distinguished  from  all 
the  neighboring  tissues. 

After  this  period,  the  process  of  atrophy 
and  degeneration  goes  on  rapidly.  The 
clot  becomes  constantly  more  dense  and 
shrivelled,  and  is  soon  converted  into  a 
minute,  stellate,  white,  or  reddish  white 
cicatrix.  The  yellow  wall  becomes  softer 
and  more  friable,  as  is  the  case  with  all 
31 


Fig.  173. 


,4:^ 


OvART,  showing  corpus  lu- 
teum, nine  weeks  after  menstrua- 
tion ;  from  a  girl  dead  of  tuber- 
cular meningitis. 


482  MENSTEUATION    AND    PEEGNANCY. 

tissues  undergoing  fatty  degeneration,  and  shows  less  distinctly 
the  markings  of  its  convolutions.  At  the  same  time,  its  edges 
become  confounded  with  the  central  coagulum  on  the  one  hand, 
and  the  neighboring  tissues  on  the  other,  so  that  it  is  no  longer 
possible  to  separate  them  fairly  from  each  other.  At  the  end  of 
eight  or  nine  weeks  the  whole  body  is  reduced  to  the  condition  of 
an  insignificant,  yellowish,  cicatrix-like  spot,  measuring  less  than  a 
quarter  of  an  inch  in  its  longest  diameter,  in  which  the  original 
texture  of  the  corpus  luteum  can  be  recognized  only  by  the  pecu- 
liar folding  and  coloring  of  its  constituent  parts.  Subsequently  its 
atrophy  goes  on  in  a  less  active  manner,  and  a  period  of  seven  or 
eight  months  sometimes  elapses  before  its  final  and  complete  dis- 
appearance. 

The  corpus  luteum,  accordingly,  is  a  formation  which  results 
from  the  filling  up  and  obliteration  of  a  ruptured  Graafian  follicle. 
Under  ordinary  conditions,  a  corpus  luteum  is  produced  at  every 
menstrual  period ;  and  notwithstanding  the  rapidity  with  which  it 
retrogrades  and  becomes  atrophied,  a  new  one  is  always  formed 
before  its  predecessor  has  completely  disappeared. 

When,  therefore,  we  examine  the  ovaries  of  a  healthy  female,  in 
whom  the  menses  have  recvirred  with  regularity  for  some  time 
previous  to  death,  several  corpora  lutea  will  be  met  with  in  different 
stages  of  formation  and  atrophy.  Thus  we  have  found,  under  such 
circumstances,  four,  five,  six,  and  even  eight  corpora  lutea  in  the 
ovaries  at  the  same  time,  perfectly  distinguishable  by  their  texture, 
but  very  small,  and  most  of  them  evidently  in  a  state  of  advanced 
retrogression.  They  finally  disappear  altogether,  and  the  number 
of  those  present  in  the  ovary,  therefore,  no  longer  corresponds  with 
that  of  the  Graafian  follicles  which  have  been  ruptured. 


II.  CORPUS  LUTEUM  OF  PREGNANCY. 

Since  the  process  above  described  takes  place  at  every  menstrual 
period,  it  is  independent  of  impregnation  and  even  of  sexual  inter- 
course. The  mere  presence  of  a  corpus  luteum,  therefore,  is  no 
indication  that  pregnancy  has  existed,  but  only  that  a  Graafian 
follicle  has  been  ruptured,  and  its  contents  discharged.  We  find, 
nevertheless,  that  when  pregnancy  does  take  place,  the  appearance 
of  the  corpus  luteum  becomes  so  much  altered  as  to  be  readily  dis- 
tinguished from  that  which  simply  follows  the  ordinary  menstrual 


CORPUS  LUTEUM  OF  PREGNANCY.  483 

process.  It  is  proper,  therefore,  to  speak  of  two  kinds  of  corpora 
lutea;  one  belonging  to  menstruation,  the  other  to  pregnancy. 

The  difference  between  these  two  kinds  of  corpora  lutea  is  not 
an  essential  or  fundamental  difference ;  since  they  both  originate 
in  the  same  way,  and  are  composed  of  the  same  structures.  It 
is,  properly  speaking,  only  a  difference  in  the  degree  and  rapidity 
of  their  development.  For  while  the  corpus  luteum  of  menstrua- 
tion passes  rapidly  through  its  different  stages,  and  is  very  soon 
reduced  to  a  condition  of  atrophy,  that  of  pregnancy  continues  its 
development  for  a  long  time,  attains  a  larger  size  and  firmer  organ- 
ization, and  disappears  finally  only  at  a  much  later  period. 

This  variation  in  the  development  and  history  of  the  corpus 
luteum  depends  upon  the  unusually  active  condition  of  the  pregnant 
uterus.  This  organ  exerts  a  powerful  sympathetic  action,  during 
pregnancy,  upon  many  other  parts  of  the  system.  The  stomach 
becomes  irritable,  the  appetite  capricious,  and  even  the  mental 
faculties  and  the  moral  disposition  are  frequently  more  or  less 
affected.  The  ovaries,  however,  feel  the  disturbing  influences  of 
gestation  more  certainly  and  decidedly  than  the  other  organs,  since 
they  are  more  closely  connected  with  the  uterus  in  the  ordinary 
performance  of  their  function.  The  moment  that  pregnancy  takes 
place,  the  process  of  menstruation  is  arrested.  No  more  eggs  come 
to  maturity  and  no  more  Graafian  follicles  are  ruptured,  during  the 
whole  period  of  gestation.  It  is  not  at  all  singular,  therefore,  that 
the  growth  of  the  corpus  luteum  should  also  be  modified,  by  an 
influence  which  affects  so  profoundly  the  system  at  large,  as  well 
as  the  ovaries  in  particular. 

During  the  first  three  weeks  of  its  formation,  the  growth  of  the 
corpus  luteum  is  the  same,  in  the  impregnated,  as  in  the  unimpreg- 
nated  condition.  After  that  time,  however,  a  difference  becomes 
manifest.  Instead  of  commencing  a  retrograde  course  during  the 
fourth  week,  the  corpus  luteum  of  pregnancy  continues  its  deve- 
lopment. The  external  wall  grows  thicker,  and  its  convolutions 
more  abundant.  Its  color  alters  in  the  same  way  as  previously 
described,  and  becomes  of  a  bright  yellow  by  the  deposit  of  fatty 
matter  in  microscopic  globules  and  granules. 

By  the  end  of  the  second  month,  the  whole  corpus  luteum  has  in- 
creased in  size  to  such  an  extent  as  to  measure  seven-eighths  of  an 
inch  in  length  by  half  an  inch  in  depth.  (Fig.  174.)  The  central 
coagulum  has  by  this  time  become  almost  entirely  decolorized,  so  as 


484 


MENSTRUATION    AND    PREGNANCY. 


to  present  the  appearance  of  a  purely  fibrinous  deposit.  Sometimes 
we  find  that  a  part  of  the  serum,  during  its  separation  from  the  clot, 
has  accumulated  in  the  centre  of  the  mass,  as  in  Fig.  174,  forming  a 
little  cavity  containing  a  few  drops  of  clear  fluid  and  inclosed  by  a 
whitish,  fibrinous  layer,  the  remains  of  the  solid  portion  of  the  clot. 

It  is   this   fibrinous    layer 
^ig-  l'''^-  which  has  sometimes  been 

mistaken  for  a  distinct  or- 
ganized membrane,  lining 
the  internal  surface  of  the 
convoluted  wall,  and  which 
has  thus  led  to  the  belief 
that  the  yellow  matter  of 
the  corpus  luteum  is  nor- 
mally deposited  outside  the 
membrane  of  the  Graafian 
follicle.  Such,- however,  is 
not  its  real  structure.  The  convoluted  wall  of  the  corpus  luteum 
is  the  membrane  of  the  follicle  itself,  partially  altered  by  hyper- 
trophy, as  may  be  readily  seen  by  examination  in  the  earlier  stages 
of  its  growth ;  and  the  fibrinous  layer,  situated  internally,  is  the 
original  bloody  coagulum,  decolorized  and  condensed  by  continued 
absorption.  The  existence  of  a  central  cavity,  containing  serous 
fluid,  is  merely  an  occasional,  not  a  constant  phenomenon.  More 
frequently,  the  fibrinous  clot  is  solid  throughout,  the  serum  being 
gradually  absorbed,  as  it  separates  spontaneously  from  the  coagulum. 

During  the  third  and  fourth 


CoRPns    Ll'TECM   of   pi'egnancy,  at   end  of  second 
mouth  :  from  a  woman  dead  from  induced  abortion. 


Fig.  175. 


Corpus  Luteum  of  pregnancy,  at  end  ■>(  fourth 
month  ;  from  a  woman  dead  by  poison. 


months,  the  enlargement  of  the 
corpus  luteum  continues;  so 
that  at  the  end  of  that  time  it 
may  measure  seven-eighths  of 
an  inch  in  length  by  three- 
quarters  of  an  inch  in  depth. 
(Fig.  175.)  The  convoluted 
wall  is  still  thicker  and  more 
highly  developed  than  before, 
having  a  thickness,  at  its  deep- 
est part,  of  three  sixteenths  of 
an  inch.  Its  color,  however,  has 
already  begun  to  fade,  and  is 


COKPUS  LUTEUM  OF  PEEGNANCY. 


485 


Fig.  176. 


now  of  a  dull  yellow,  instead  of  the  bright,  clear  tinge  which  it 
previously  exhibited.  The  central  coagulum,  perfectly  colorless 
and  fibrinous  in  appearance,  is  often  so  much  flattened  out,  by  the 
lateral  compression  of  its  mass,  that  it  has  hardly  a  line  in  thickness. 
The  other  relations  of  the  different  parts  of  the  corpus  luteum 
remain  the  same. 

The  corpus  luteum  has  now  attained  its  maximum  of  develop- 
ment, and  remains  without  any  very  perceptible  alteration  during 
the  fifth  and  sixth  months.  It  then  begins  to  retrograde,  diminish- 
ing constantly  in  size  during  the  seventh  and  eighth  months.  Its 
external  wall  fades  still  more  perceptibly  in  color,  becoming  of  a 
faint  yellowish  white,  not  unlike  that  which  it  presented  at  the  end 
of  the  third  week.  Its  texture  is  thick,  soft,  and  elastic,  and  it  is 
still  strongly  convoluted.  An  abundance  of  fine  red  vessels  can  be 
seen  penetrating  from  the  exterior  into  the  interstices  of  its  con- 
volutions. The  central  coagulum  is  reduced  by  this  time  to  the 
condition  of  a  whitish,  radiated  cicatrix. 

The  atrophy  of  the  organ  continues  during  the  ninth  month. 
At  the  termination  of  pregnancy,  it  is  re- 
duced to  the  size  of  half  an  inch  in  length 
and  three-eighths  of  an  inch  in  depth. 
(Fig.  176.)  It  is  then  of  a  faint  indefinite 
hue,  but  little  contrasted  with  the  remain- 
ing tissues  of  the  ovary.  The  central  cica- 
trix has  become  very  small,  and  appears 
only  as  a  thin  whitish  lamina  with  radiating 
processes  which  run  in  between  the  inter- 
stices of  the  convolutions.  The  whole  mass, 
however,  is  still  quite  firm  and  resisting  to 
the  touch,  and  is  readily  distinguishable, 
both  from  its  size  and  texture,  as  a  pro- 
minent feature  in  the  ovarian  tissue,  and  a 
reliable  indication  of  pregnancy.  The  con- 
voluted structure  of  its  external  wall  is 
very  perceptible,  and  the  point  of  rupture, 
with  its  external  peritoneal  cicatrix,  distinctly  visible. 

After  delivery,  the  corpus  luteum  retrogrades  rapidly.  At  the 
end  of  eight  or  nine  weeks,  it  has  become  so  much  altered  that  its 
color  is  no  longer  distinguishable,  and  only  faint  traces  of  its  con- 
voluted structure  are  to  be  discovered  by  close  examination.    These 


Corpus  Lpteum  of  preg- 
nancy, at  term  ;  from  a  woman 
dead  in  delivery  from  rupture 
of  the  uterus. 


486  MENSTRUATION    AND    PREGNANCY. 

traces  may  remain,  however,  for  a  long  time  afterward,  more  or  less 
concealed  in  the  ovarian  tissue.  We  have  distinguished  them  so 
late  as  nine  and  a  half  months  after  delivery.  They  finally  disap- 
pear entirely,  together  with  the  external  cicatrix  which  previously 
marked  their  situation. 

During  the  existence  of  gestation,  the  process  of  menstruation 
being  suspended,  no  new  follicles  are  ruptured,  and  no  new  corpora 
lutea  produced ;  and  as  the  old  ones,  formed  before  the  period  of 
conception,  gradually  fade  and  disappear,  the  corpus  luteum  which 
marks  the  occurrence  of  pregnancy  after  a  short  time  exists  alone 
in  the  ovary,  and  is  not  accompanied  by  any  others  of  older  date. 
In  twin  pregnancies,  we  of  course  find  two  corporea  lutea  in  the 
ovaries ;  but  these  are  precisely  similar  to  each  other,  and,  being 
evidently  of  the  same  date,  will  not  give  rise  to  any  confusion. 
Where  there  is  but  a  single  foetus  in  the  uterus,  and  the  ovaries 
contain  two  corpora  lutea  of  similar  appearance,  one  of  them 
belongs  to  an  embryo  which  has  been  blighted  by  some  accident 
in  the  early  part  of  pregnancy.  The  remains  of  the  blighted  em- 
bryo may  often  be  discovered,  in  such  cases,  in  some  part  of  the 
Fallopian  tubes,  where  it  has  been  arrested  in  its  descent  toward 
the  uterus. 

After  the  process  of  lactation  comes  to  an  end,  the  ovaries  again 
resume  their  ordinary  function.  The  Graafian  follicles  mature  and 
rupture  in  succession,  as  before,  and  new  corpora  lutea  follow  each 
other  in  alternate  development  and  disappearance. 

We  find,  then,  that  the  corpus  luteum  of  menstruation  differs  from 
that  of  pregnancy  in  the  extent  of  its  development  and  the  dura- 
tion of  its  existence.  While  the  former  passes  through  all  the  im- 
portant phases  of  its  growth  and  decline  in  the  period  of  two 
months,  the  latter  lasts  for  from  nine  to  ten  months,  and  presents, 
during  a  great  portion  of  the  time,  a  larger  size  and  a  more  solid 
organization.  It  will  be  observed  that,  even  with  the  corpus  luteum 
of  pregnancy,  the  bright  yellow  color,  which  is  so  important  a  cha- 
racteristic, is  only  temporary  in  its  duration ;  not  making  its  appear- 
ance till  about  the  end  of  the  fourth  week,  and  disappearing  after 
the  sixth  month. 

The  following  table  contains,  in  a  brief  form,  the  characters  of 
the  corpus  luteum,  as  belonging  to  the  two  different  conditions  of 
menstruation  and  pregnancy,  corresponding  with  different  periods 
of  its  development. 


CORPUS  LUTEUM  OF  PREGNANCY. 


487 


At  the  end  of 
three  weeks 
One  month 

Two  months 


Six  months 


Nine  months 


CoKPus  Ldteum  of  Menstruation.       Corpus  Luteum  of  Pregnancy. 
Three-quarters  of  an  inch  in  diameter ;  central  clot  reddish ;  con- 
voluted wall  pale. 


Smaller;  convoluted  wall  bright 
yellow  ;  clot  still  reddish. 

Reduced  to  the  condition  of  an 
insignificant  cicatrix. 


Absent. 


Absent. 


Larger;  convoluted  wall  bright 
yellow ;  clot  still  reddish. 

Seven-eighths  of  an  inch  in  dia- 
meter; convoluted  wall  bright 
yellow;  clot  perfectly  decolor- 
ized. 

Still  as  large  as  at  end  of  second 
month;  clot  fibrinous;  convo- 
luted wall  paler. 

One-half  an  inch  in  diameter ; 
central  clot  converted  into  a 
radiating  cicatrix ;  the  external 
wall  tolerably  thick  and  convo- 
luted, but  without  any  bright 
yellow  color. 


488     DEVELOPMENT  OF  THE  IMPREGNATED  EGG. 


CHAPTER    VII. 

ON  THE  DEVELOPMENT  OF  THE  IMPREGNATED  EGG 
—SEGMENTATION  OF  THE  VI  T  EL  L  US— BL  A  STODER- 
MIC  MEMBRANE  — FORMATION  OF  ORGANS  IN  THE 
FROG. 

We  have  seen,  in  the  foregoing  chapters,  how  the  egg,  produced 
in  the  ovarian  follicle,  becomes  gradually  developed  and  ripened, 
until  it  is  ready  to  be  discharged.  The  egg,  accordingly,  passes 
through  several  successive  stages  of  formation,  even  while  still  con- 
tained within  the  ovary;  and  its  vitellus  becomes  gradually  com- 
pleted, by  the  formation  of  albuminous  material  and  the  deposit  of 
molecular  granulations.  The  last  change  which  the  egg  undergoes, 
in  this  situation,  and  which  marks  its  complete  maturity,  is  the  dis- 
appearance of  the  germinative  vesicle.  This  vesicle,  which  is,  in 
general,  a  prominent  feature  of  the  ovarian  egg,  disappears  but  a 
short  time  previous  to  its  discharge,  or  even  just  at  the  period  of 
its  leaving  the  Graafian  follicle. 

The  egg,  therefore,  consisting  simply  of  the  mature  vitellus  and 
the  vitelline  membrane,  comes  in  contact,  after  leaving  the  ovary, 
and  while  passing  through  the  Fallopian  tube,  with  the  spermatic 
fluid,  and  thereby  becomes  fecundated.  By  the  influence  of  fecun- 
dation, a  new  stimulus  is  imparted  to  its  growth ;  and  while  the 
vitality  of  the  unimpregnated  germ,  arrived  at  this  point,  would 
have  reached  its  termination,  the  fecundated  egg,  on  the  contrary, 
starts  upon  a  new  and  more  extensive  course  of  development,  by 
which  it  is  finally  converted  into  the  body  of  the  young  animal. 

The  egg,  in  the  first  place,  as  it  passes  down  the  Fallopian  tube, 
becomes  covered  with  an  albuminous  secretion.  In  the  birds,  as  we 
have  seen,  this  secretion  is  very  abundant,  and  is  deposited  in  suc- 
cessive layers  around  the  vitellus.  In  the  reptiles,  it  is  also  poured 
out  in  considerable  quantity,  and  serves  for  the  nourishment  of  the 
egg  during  its  early  growth.  In  quadrupeds,  the  albuminous  matter 
is  supplied  in  the  same  way,  though  in  smaller  quantity,  by  the 


SEGMENTATION    OF    THE    VITELLUS. 


489 


mucous  membrane  of  the  Fallopian  tubes,  and  envelopes  the  egg  in 
a  layer  of  nutritious  material. 

A  very  remarkable  change  now  takes  place  in  the  impregnated  egg, 
which  is  known  as  the  spontaneous  division,  or  segyneiitation,  of  the 
vitellus.  A  furrow  first  shows  itself, 
running  round  the  globular  mass  of  the 
vitellus  in  a  vertical  direction,  which 
gradually  deepens  until  it  has  divided 
the  vitellus  into  two  separate  halves  or 
hemispheres.  (Fig.  177,  a.)  Almost  at 
the  same  time  another  furrow,  running 
at  right  angles  with  the  first,  penetrates 
also  the  substance  of  the  vitellus  and 
cuts  it  in  a  transverse  direction.  The 
vitellus  is  thus  divided  into  four  equal 
portions  (Fig.  177,  b),  the  edges  and 
angles  of  which  are  rounded  off,  and 
which  are  still  contained  in  the  cavity 
of  the  vitelline  membrane.  The  spaces 
between  them  and  the  internal  surface 
of  the  vitelline  membrane  are  occu- 
pied by  a  transparent  fluid. 

The  process  thus  commenced  goes 
on  by  a  successive  formation  of  fur- 
rows and  sections,  in  various  direc- 
tions. The  four  vitelline  segments 
already  produced  are  thus  subdivided 
into  sixteen,  the  sixteen  into  sixty- 
four,  and  so  on;  until  the  whole  vi- 
tellus is  converted  into  a  mulberry 
shaped  mass,  composed  of  minute, 
nearly  spherical  bodies,  which  are 
called  the  "vitelline  spheres."  (Fig. 
177,  c.)  These  vitelline  spheres  have 
a  somewhat  firmer  consistency  than 
the  original  substance  of  the  vitellus; 
and  this  consistency  appears  to  in- 
crease, as  they  successively  multiply 
in  numbers  and  diminish  in  size.  At  last  they  have  become  so 
abundant  as  to  be  closely  crowded  together,  compressed  into  poly- 
gonal forms,  and  flattened  against  the  internal  surface  of  the  vitel- 


Segmextation  of  the  Vitellus. 


490     DEVELOPMENT  OF  THE  IMPREGNATED  EGG. 

line  membrane.  (Fig.  177,  d)  They  have  by  this  time  been  con- 
verted into  true  animal  cells;  and  these  cells,  adhering  to  each  other 
by  their  adjacent  edges,  form  a  continuous  organized  membrane, 
which  is  termed  the  Blastodermic  mewhrane. 

During  the  formation  of  this  membrane,  moreover,  the  egg,  while 
passing  through  the  Fallopian  tubes  into  the  uterus,  has  increased 
in  size.  The  albuminous  matter  with  which  it  was  enveloped  has 
liquefied;  and,  being  absorbed  by  endosmosis  through  the  vitelline 
membrane,  has  furnished  the  materials  for  the  more  solid  and  ex- 
tensive growth  of  the  newly-formed  structures.  It  may  also  be 
seen  that  a  large  quantity  of  this  fluid  has  accumulated  in  the 
central  cavity  of  the  egg^  inclosed  accordingly  by  the  blastodermic 
membrane,  with  the  original  vitelline  membrane  still  forming  an 
external  envelope  round  the  whole. 

The  next  change  which  takes  place,  consists  in  the  division  or 
splitting  of  the  blastodermic  membrane  into  two  layers,  which  are 
known  as  the  external  and  internal  layers  of  the  blastodermic  membrane. 
They  are  both  still  composed  exclusively  of  cells ;  but  those  of  the 
external  layer  are  usually  smaller  and  more  compact,  while  those 
of  the  internal  are  rather  larger  and  looser  in  texture.  The  egg 
ihen  presents  the  appearance  of  a  globular  sac,  the  walls  of  which 
consist  of  three  concentric  layers,  lying  in  contact  with  and  inclos- 
ing each  other,  viz.,  1st,  the  structureless  vitelline  membrane  on  the 
outside ;  2d,  the  external  layer  of  the  blastodermic  membrane,  com- 
posed of  cells ;  and  3d,  the  internal  layer  of  the  blastodermic  mem- 
brane, also  composed  of  cells.  The  cavity  of  the  egg  is  occupied 
by  a  transparent  fluid,  as  above  mentioned. 

This  entire  process  of  the  segmentation  of  the  vitellus  and  the 
formation  of  the  blastodermic  membrane  is  one  of  the  most  re- 
markable and  important  of  all  the  changes  which  take  place  during 
the  development  of  the  egg.  It  is  by  this  process  that  the  simple 
globular  mass  of  the  vitellus,  composed  of  an  albuminous  matter 
and  oily  granules,  is  converted  into  an  organized  structure.  For 
the  blastodermic  membrane,  though  consisting  only  of  cells  nearly 
uniform  in  size  and  shape,  is  nevertheless  a  truly  organized  mem- 
brane, made  up  of  fully  formed  anatomical  elements.  It  is,  more- 
over, the  first  sign  of  distinct  organization  which  makes  its  appear- 
ance in  the  egg;  and  as  soon  as  it  is  completed,  the  body  of  the 
new  foetus  is  formed.  The  blastodermic  membrane  is,  in  fact,  the 
body  of  the  foetus.  It  is  at  this  time,  it  is  true,  exceedingly  simple 
in  texture ;  but  we  shall  see  hereafter  that  all  the  future  organs 


BLASTODERMIC    MEMBRANE.  491 

of  the  body,  however  varied  and  complicated  in  structure,  arise  out 
of  it,  by  modification  and  development  of  its  different  parts. 

The  segmentation  of  the  vitellus,  moreover,  and  the  formation 
of  the  blastodermic  membrane,  take  place  in  essentially  the  same 
manner  in  all  the  different  classes  of  animals.  It  is  always  in  this 
way  that  the  egg  commences  its  development,  whether  it  be  des- 
tined to  form  afterward  a  fish  or  a  reptile,  a  bird,  a  quadruped  or  a 
man.  The  peculiarities  belonging  to  different  species  show  them- 
selves afterward,  by  variations  in  the  manner  and  extent  of  the 
development  of  different  parts.  In  the  higher  animals  and  in  the 
human  subject  the  development  of  the  egg  becomes  an  exceedingly 
complicated  process,  owing  to  the  formation  of  various  accessory 
organs,  which  are  made  requisite  by  the  peculiar  conditions  under 
which  the  development  of  the  embryo  takes  place.  It  is,  in  fact, 
impossible  to  describe  or  understand  properly  the  complex  embry- 
ology of  the  quadrupeds,  and  more  particularly  that  of  the  human 
subject,  without  first  tracing  the  development  of  those  species  in 
which  the  process  is  more  simple.  We  shall  commence  our  descrip- 
tion, therefore,  with  the  development  of  the  egg  of  the  frog,  which 
is  for  many  reasons  particularly  appropriate  for  our  purpose. 

The  egg  of  the  frog,  when  discharged  from  the  body  of  the  female 
and  fecundated  by  the  spermatic  fluid  of  the  male,  is  deposited  in 
the  water,  enveloped  in  a  soft  elastic  cushion  of  albuminous  sub- 
stance. It  is  therefore  in  a  situation  where  it  is  freely  exposed  to 
the  light,  the  air,  and  the  moderate  warmth  of  the  sun's  rays,  and 
where  it  can  absorb  directly  an  abundance  of  moisture  and  of  ap- 
propriate nutritious  material.  We  find  accordingly  that  under 
these  circumstances  the  development  of  the  egg  is  distinguished 
by  a  character  of  great  simplicity ;  since  the  whole  of  the  vitellus  is 
directly  converted  into  the  body  of  the  embryo.  There  are  no  accessory 
organs  required,  and  consequently  no  complication  of  the  formative 
process. 

The  two  layers  of  the  blastodermic  membrane,  above  described, 
represent  together  the  commencement  of  all  the  organs  of  the  foetus. 
They  are  intended,  however,  for  the  production  of  two  different 
systems ;  and  the  entire  process  of  their  development  may  be  ex- 
pressed as  follows  :  The  external  layer  of  the  blastodermic  membrane 
produces  the  spinal  column  and  all  the  organs  of  animal  life;  while  the 
internal  layer  produces  the  intestinal  canal,  and  all  the  organs  of  vege- 
tative life. 

The  first  sign  of  advancing  organization  in  the  external  layer  of 


492     DEVELOPMENT  OF  THE  IMPREGNATED  EGG. 

the  blastodermic  membrane  shows  itself  in  a  thickening  and  con- 
densation of  its  structure.  This  thickened  portion  has  the  form  of  an 
elongated  oval-shaped  spot,  termed  the  "embryonic  spot"  (Fig.  178), 

the  wide  edges  of  which  are  somewhat 
more  opaque  than  the  rest  of  the  blasto- 
dermic membrane.  Inclosed  within 
these  opaque  edges  is  a  narrower  color- 
less and  transparent  space,  the  "area 
pellucida,"  and  in  its  centre  is  a  delicate 
line,  or  furrow,  running  longitudinally 
from  front  to  rear,  which  is  called  the 
"  primitive  trace." 

On  each  side  of  the  primitive  trace, 
1.VPREGXATEI,  E G r, ,  with  com-    ^^  thc  arca  pellucida,  the  substance  of 
mencement  of  forniaiion  of  embryo:     |;}]e  blastodermic  membrane  riscs  up  in 

shoTving   erabrvonic  spot,  area  pellu-  „  , 

cida,  and  primuive  trace.  such  a  manner  as  to  torm  two  nearly 

parallel  vertical  plates  or  ridges,  which 
approach  each  other  over  the  dorsal  aspect  of  the  fcetus  and  are 
therefore  called  the  "dorsal  plates."  They  at  last  meet  on  the 
median  line,  so  as  to  inclose  the  furrow  above  described  and  con- 
vert it  into  a  canal.  This  afterward  becomes  the  spinal  canal,  and 
in  its  cavity  is  formed  the  spinal  cord,  by  a  deposit  of  nervous 
matter  upon  its  internal  surface.  At  the  anterior  extremity  of  this 
canal,  its  cavity  is  large  and  rounded,  to  accommodate  the  brain 
and  medulla  oblongata;  at  its  posterior  extremity  it  is  narrow  and 
pointed,  and  contains  the  extremity  of  the  spinal  cord. 

In  a  transverse  section  of  the  egg  at  this  stage  (Fig.  179),  the 
dorsal  plates  may  be  seen  approaching  each  other  above,  on  each 
side  of  the  primitive  furrow  or  "trace."  At  a  more  advanced 
period  (Fig.  180)  they  may  be  seen  fairly  united  with  each  other, 
so  as  to  inclose  the  cavity  of  the  spinal  canal.  At  the  same  time, 
the  edges  of  the  thickened  portion  of  the  blastodermic  membrane 
grow  outward  and  downward,  so  as  to  spread  out  more  and  more 
over  the  lateral  portions  of  the  vitelline  mass.  These  are  called 
the  "abdominal  plates;"  and  as  they  increase  in  extent  they  tend 
to  unite  with  each  other  below  and  inclose  the  abdominal  cavity, 
just  as  the  dorsal  plates  unite  above,  and  inclose  the  spinal  canal. 
At  last  the  abdominal  plates  actually  do  unite  with  each  other  on 
the  median  line  (at  i.  Fig.  180),  embracing  of  course  the  whole 
internal  layer  of  the  blastodermic  membrane  (5),  which  incloses  in 


FORMATION    OF    ORGANS. 


498 


its  turn  the  remains  of  the  original  vitellus  and  the  albuminous 
fluid  which  has  accumulated  in  its  cavity. 


Fig.  179. 


Fig.  180. 


Transverse  section  of  Egg  in  an  early 
stage  of  development  — 1.  External  layer 
of  blastodermic  membrane.  2,2.  Dorsal 
plates.  3.  Internal  layer  of  blastodermic 
membrane. 


1  .MPREG  N.A.TED  EoQ,  at  a  SOmeTvhHt 
more  advanced  period. — 1.  Umbilicus,  or 
point  of  union  between  abdominal  plates. 
2,  2.  Dorsal  plates  united  -with  each  other 
on  the  median  line  and  inclosing  the  spinal 
canal.  3,  3.  Abdominal  plates.  4.  Sec- 
tion of  spinal  column,  with  laminae  and 
ribs.  5.  Internal  layer  of  blastodermic 
membrane. 


During  this  time,  there  is  formed,  in  the  thickness  of  the  external 
blastodermic  layer,  immediately  beneath  the  spinal  canal,  a  longitu- 
dinal cartilaginous  cord,  called  the  "chorda  dorsalis."  Around  the 
chorda  dorsalis  are  afterward  developed  the  bodies  of  the  vertebrae 
(Fig.  180,  4),  forming  the  chain  of  the  vertebral  column;  and  the 
oblique  processes  of  the  vertebrae  run  upward  from  this  point  into  the 
dorsal  plates ;  while  the  transverse  processes,  and  ribs,  run  outward 
and  downward  in  the  abdominal  plates,  to  encircle  more  or  less 
completely  the  corresponding  portion  of  the  body. 

If  we  now  examine  the  egg  in  longitudinal  section,  while  this 
process  is  going  on,  the  thickened  portion  of  the  external  blastoder 
mic  layer  may  be  seen  in  profile,  as  at  i,  Fig.  181.  The  anterior 
portion  (2),  which  will  form  the  head,  is  thicker  than  the  posterior 
(3),  Avhich  will  form  the  tail  of  the  young  animal.  As  the  whole 
mass  grows  rapidly,  both  in  the  anterior  and  posterior  direction, 
the  head  becomes  very  thick  and  voluminous,  while  the  tail  also 
begins  to  project  backward,  and  the  whole  egg  assumes  a  distinctly 
elongated  form.  (Fig.  182.)  The  abdominal  plates  at  the  same  time- 
meet  upon  its  under  surface,  and  the  point  at  which  they  finally 


494 


DEYELOPMENT  OF  THE  IMPREGNATED  EGG. 


unite  forms  the  abdominal  cicatrix  or  umbilicus.    The  internal  blas- 
todermic layer  is  seen,  of  course,  in  the  longitudinal  section  of  the 


Fie.  181. 


Fig.  182. 


Diagram  of  Frog's  Egg,  in  an  parly  E(jg  of  Frog,  in  process  of  develop- 

Rfage  of  development ;  longitudinal  sec-  meui. 

tiou. — 1  Thickened  portion  of  external 
blastodermic  layer,  forming  body  of  foetus. 
2.  Anterior  extremity  of  foetus.  .3.  Poste- 
rior extremity.  4.  Internal  layer  of  blas- 
todermic membrane.   5.  Cavity  of  vitellus. 

egg,  as  well  as  in  the  transverse,  embraced  by  the  abdominal  plates, 
and  inclosing,  as  before,  the  renaains  of  the  vitellus. 

As  the  development  of  the  above  parts  goes  on  (Fig.  183),  the 
head  becomes  still  larger,  and  soon  shows  traces  of  the  formation 

Fig.  183. 


OF   Frog,   farther  advanced. 


of  organs  of  special  sense.  The  tail  also  increases  in  size,  and  pro- 
jects farther  from  the  posterior  extremity  of  the  embryo.  The 
spinal  cord  runs  in  a  longitudinal  direction  from  front  to  rear,  and 
its  anterior  extremity  enlarges,  so  as  to  form  the  brain  and  medulla 
oblongata.  In  the  mean  time,  the  internal  blastodermic  layer,  which 
is  subsequently  to  be  converted  into  the  intestinal  canal,  has  been 
shut  in  by  the  abdominal  walls,  and  still  forms  a  perfectly  closed 
sac,  of  a  slightly  elongated  figure,  without  either  inlet  or  outlet. 
Afterward,  the  mouth  is  formed  by  a  process  of  atrophy  and  per- 
ibration,  which  takes  place  through  both  external  and  internal  layers, 
at  the  anterior  extremity,  while  a  similar  perforation,  at  the  poste- 
rior extremity,  results  in  the  formation  of  the  anus. 


FORMATION    OF    ORGANS.  495 

All  these  parts,  however,  are  as  yet  imperfect;  and,  being  merely 
in  the  course  of  formation,  are  incapable  of  performing  any  active 
function. 

By  a  continuation  of  the  same  process,  the  different  portions  of 
the  external  blastodermic  layer  are  further  developed,  so  as  to  re- 
sult in  the  complete  formation  of  the  various  parts  of  the  skeleton, 
the  integument,  the  organs  of  special  sense,  and  the  voluntary 
nerves  and  muscles.  The  tail  at  the  same  time  acquires  sufficient 
size  and  strength  to  be  capable  of  acting  as  an  organ  of  locomo- 
tion. (Fig.  184.)     The  intestinal  canal,  which  has  been  formed  from 

Fig.  184. 


T  A  B  p  o  L  E  fully  developed. 

the  internal  blastodermic  layer,  is  at  first  a  short,  wide,  and  nearly 
straight  tube,  running  directly  from  the  mouth  to  the  anus.  It 
soon,  however,  begins  to  grow  faster  than  the  abdominal  cavity 
which  incloses  it,  becoming  longer  and  narrower,  and  is  at  the  same 
time  thrown  into  numerous  convolutions.  It  thus  presents  a  larger 
internal  surface  for  the  performance  of  the  digestive  process. 

Arrived  at  this  period,  the  young  tadpole  ruptures  the  vitelline 
membrane,  by  which  he  has  heretofore  been  inclosed,  and  leaves  the 
cavity  of  the  egg.  He  at  first  fastens  himself  upon  the  remains  of 
the  albuminous  matter  deposited  round  the  egg,  and  feeds  upon  it  for 
a  short  period.  He  soon,  however,  acquires  sufficient  strength  and 
activity  to  swim  about  freely  in  search  of  other  food,  propelling 
himself  by  means  of  his  large,  membranous,  and  muscular  tail. 
The  alimentary  canal  increases  very  rapidly  in  length  and  becomes 
spirally  coiled  up  in  the  abdominal  cavity,  so  as  to  attain  a  length 
from  seven  to  eight  times  greater  than  that  of  the  entire  body. 

After  a  time,  a  change  takes  place  in  the  external  form  of  the 
young  animal.  Anterior  and  posterior  extremities  or  limbs  begin  to 
show  themselves,  by  budding  or  sprouting  from  the  corresponding 
regions  of  the  body.  (Fig.  185.)  At  first  these  organs  are  very 
small,  imperfect  in  structure,  and  altogether  useless  for  purposes  of 


496 


DEVELOPMENT  OF  THE  IMPREGNATED  EGG. 


locomotion.  Thej  soon,  however,  increase  in  size  and  strength ; 
and  while  thej  keep  pace  with  the  increasing  development  of  the 
whole  body,  the  tail  on  the  contrary  ceases  to  grow,  and  becomes 
shrivelled  and  atrophied.  The  limbs,  in  fact,  are  destined  finally 
to  replace  the  tail  as  organs  of  locomotion ;  and  a  time  at  last 
arrives  (Fig.  186)  when  the  tail  has  altogether  disappeared,  while 


Fig.  185. 


Fisj.  186. 


Tadpole,  with  limbs  begiuoiug  to  be  formed. 


Perfect  Frog. 


the  legs  have  become  fully  developed,  muscular  and  powerful. 
Then  the  animal,  which  was  before  confined  to  an  aquatic  mode 
of  life,  becomes  capable  of  living  also  upon  land,  and  a  trans- 
formation is  effected  from  the  tadpole  into  the  perfect  frog. 

During  the  same  time,  other  changes  of  an  equally  important 
character  have  taken  place  in  the  internal  organs.  The  tadpole  at 
first  breathes  by  gills;  but  these  organs  subsequently  become 
atrophied  and  disappear,  being  finally  replaced  by  well  developed 
lungs.  The  structure  of  the  mouth,  also,  of  the  integument,  and 
of  the  circulatory  system,  is  altered  to  correspond  with  the  varying 
conditions  and  wants  of  the  growing  animal ;  and  all  these  changes, 
taking  place  in  part  successively  and  in  part  simultaneously,  bring 
the  animal  at  last  to  a  state  of  complete  formation. 

The  process  of  development  may  then  be  briefly  recapitulated  as 
follows: — 

1.  The  blastodermic  membrane,  produced  by  the  segmentation 
of  the  vitellus,  consists  of  two  cellular  layers,  viz.,  an  external  and 
an  internal  blastodermic  layer. 

2.  The  external  layer  of  the  blastodermic  membrane  incloses  by 
its  dorsal  plates  the  cerebro-spinal  canal,  and  by  its  abdominal 
plates  the  abdominal  or  visceral  cavity. 


FORMATION  OF  ORGANS  IN  THE  FROG.       497 

3.  The  internal  layer  of  the  blastodermic  membrane  forms  the 
intestinal  canal,  which  becomes  lengthened  and  convoluted,  and 
communicates  with  the  exterior  by  a  mouth  and  anus  of  secondary 
formation. 

4.  Finally  the  cerebro-spinal  axis  and  its  nerves,  the  skeleton, 
the  organs  of  special  sense,  the  integument,  and  the  muscles,  are 
developed  from  the  external  blastodermic  layer ;  while  the  anterior 
and  posterior  extremities  are  formed  from  the  same  layer  by  a  pro- 
cess of  sprouting,  or  continuous  growth. 


32 


498 


THE    UMBILICAL    VESICLE. 


CHAPTER   VIII. 


THE    UMBILICAL  VESICLE, 


Fig.  187. 


In"  the  frog,  as  we  have  seen,  the  abdominal  plates,  closing 
together  in  front  and  underneath  the  body  of  the  animal,  shut  in 
directly  the  whole  of  the  vitellus,  and  join  each  other  upon  the 
median  line,  at  the  umbilicus.  The  whole  remains  of  the  vitellus 
are  then  inclosed  in  the  abdomen  of  the  animal,  and  in  the  intestinal 
sac  formed  by  the  internal  blastodermic  layer. 

In  many  instances,  however,  as,  for  example,  in  several  kinds  of 
fish,  and  in  all  the  birds  and  quadrupeds,  the  abdominal  plates  do 

not  immediately  embrace  the  whole  of 
the  vitelline  mass,  but  tend  to  close 
together  about  its  middle ;  so  that  the 
vitellus  is  constricted,  in  this  way,  and 
divided  into  two  portions:  one  internal, 
and  one  external.  (Fig.  187.)  As  the 
process  of  development  proceeds,  the  body 
of  the  foetus  increases  in  size,  out  of  pro- 
portion to  the  vitelline  sac,  and  the  con- 
striction just  mentioned  becomes  at  the 
same  time  more  strongly  marked ;  so  that 
the  separation  between  the  internal  and  external  portions  of  the 
vitelline  sac  is  nearly  complete.  (Fig.  188.)  The  internal  layer  of 
the  blastodermic  membrane  is  by  the  same  means  divided  into 
two  portions,  one  of  which  forms  the  intestinal  canal,  while  the 
other,  remaining  outside,  forms  a  sac-like  appendage  to  the  abdo- 
men, which  is  known  by  the  name  of  the  umbilical  vesicle. 

The  umbilical  vesicle  is  accordingly  lined  by  a  portion  of  the 
internal  blastodermic  layer,  continuous  with  the  mucous  membrane 
of  the  intestinal  canal;  while  it  is  covered  on  the  outside  by  a  por- 
tion of  the  external  blastodermic  layer,  continuous  with  the  integu- 
ment of  the  abdomen. 


EfiQOF    Fish;  showing  forma 
tioa  of  umbilical  vesicle. 


THE    UMBILICAL    VESICLE.  499 

After  the  young  animal  leaves  the  egg,  the  umbilical  vesicle 
sometimes  becomes  withered  and  atrophied  by  the  absorption  of  its 
contents;  while  in  some  instances,  the  abdominal  walls  gradually 

Fig.  188. 


Young  Fish  with  umbilical  vesicle. 

extend  over  it,  and  crowd  it  back  into  the  abdomen  ;  the  nutritious 
matter  which  it  contained  passing  from  the  cavity  of  the  vesicle 
into  that  of  the  intestine  by  the  narrow  passage  or  canal  which 
remains  open  between  them. 

In  the  human  subject,  however,  as  well  as  in  the  quadrupeds,  the 
umbilical  vesicle  becomes  more  completely  separated  from  the  abdo 
men  than  in  the  cases  just  mentioned.  There  is  at  first  a  wide  com- 
munication between  the  cavity  of  the  umbilical  vesicle  and  that  of 
the  intestine ;  and  this  communication,  as  in  other  instances,  becomes 
gradually  narrowed  by  the  increasing  constriction  of  the  abdominal 
walls.  Here,  however,  the  constriction  proceeds  so  far  that  the 
opposite  surfaces  of  the  canal  come  in  contact  with  each  other,  and 
adhere;  so  that  the  narrow  passage  previously 
existing  between  the  cavity  of  the  intestine 
and  that  of  the  umbilical  vesicle  is  obliterated, 
and  the  vesicle  is  then  connected  with  the 
abdomen  only  by  an  impervious  cord.  This 
cord  afterward  elongates,  and  becomes  con- 
verted into  a  slender,  thread-like  pedicle  (Fig. 
189),  passing  out  from  the  abdomen  of  the 
foetus,  and  connected  by  its  further  extremity 
with  the  umbilical  vesicle,  which  is  filled  with 
a  transparent,  colorless  fluid.     The  umbilical       human  embryo,  with 

.,.  T-         1  ••II-         11  umbilical  vesicle ;  about  the 

vesicle  is  very  distinctly  visible  m  the  human    gfth  week. 

foetus  so  late  as  the  end  of  the  third  month. 

After  that  period  it  diminishes  in  size,  and  is  gradually  lost  in  the 

advancing  development  of  the  neighboring  parts. 

In  the  formation  of  the  umbilical  vesicle,  we  have  the  first  varia- 


500  THE    UMBILICAL    VESICLE. 

tion  from  the  simple  plan  of  development  described  in  the  preceding 
chapter.  Here,  the  whole  of  the  vitellus  is  not  directly  converted 
into  the  body  of  the  embryo ;  but  while  a  part  of  it  is  taken,  as 
usual,  into  the  abdominal  cavity,  and  used  immediately  for  the  pur- 
poses of  nutrition,  a  part  is  left  outside  the  abdomen,  in  the  umbilical 
vesicle,  a  kind  of  secondary  organ  or  appendage  of  the  foetus.  The 
contents  of  the  umbilical  vesicle,  however,  are  afterward  absorbed, 
and  so  appropriated,  finally,  to  the  nourishment  of  the  newly  formed 
tissues 


AMNION    AND    ALLANTOIS.  501 


CHAPTER    IX. 

AMNION    AND    A  LL  A  NTOIS.  — D  E  VE  LO  P  M  E  N  T   OF 
THE    CHICK. 

We  shall  now  proceed  to  the  description  of  two  other  accessory 
organs,  which  are  formed,  during  the  development  of  the  fecundated 
egg,  in  all  the  higher  classes  of  animals.  These  are  the  amnion  and 
the  allantois  ;  two  organs  which  are  always  found  in  company  with 
each  other,  since  the  object  of  the  first  is  to  provide  for  the  forma- 
tion of  the  second.  The  amnion  is  formed  from  the  external  layer 
of  the  blastodermic  membrane,  the  allantois  from  the  internal  layer. 

In  the  frog  and  in  fish,  as  we  have  seen,  the  egg  is  abundantly 
supplied  with  moisture,  air,  and  nourishment,  by  the  water  with 
which  it  is  surrounded.  It  can  absorb  directly  all  the  gaseous  and 
liquid  substances,  which  it  requires  for  the  purposes  of  nutrition 
and  growth.  The  absorption  of  oxygen,  the  exhalation  of  carbonic 
acid,  and  the  imbibition  of  albuminous  and  other  liquids,  can  all 
take  place  without  diflSculty  through  the  simple  membranes  of  the 
egg;  particularly  as  the  time  required  for  the  formation  of  the 
embryo  is  very  short,  and  as  a  great  part  of  the  process  of  develop- 
ment remains  to  be  accomplished  after  the  young  animal  leaves 
the  egg. 

But  in  birds  and  quadrupeds,  the  time  required  for  the  develop- 
ment of  the  foetus  is  longer.  The  young  animal  also  acquires  a 
much  more  perfect  organization  during  the  time  that  it  remains 
inclosed  within  the  egg;  and  the  processes  of  absorption  and  exhala- 
tion necessary  for  its  growth,  being  increased  in  activity  to  a  corre- 
sponding degree,  require  a  special  organ  for  their  accomplishment. 
This  special  organ,  destined  to  bring  the  blood  of  the  fcetus  into 
relation  with  the  atmosphere  and  external  sources  of  nutrition,  is 
the  allantois. 

In  the  frog  and  the  fish,  the  internal  blastodermic  layer,  forming 
the  intestinal  mucous  membrane,  is  inclosed  everywhere,  as  above 
described,  by  the   external  layer,   forming  the  integument;    and 


502  AMNION    AND    ALLANTOIS. 

consequently  can  nowhere  come  in  contact  with  the  investing 
membrane  of  the  egg.  But  in  the  higher  animals,  the  internal 
blastodermic  layer,  which  is  the  seat  of  the  greatest  vascularity, 
and  which  is  destined  to  produce  the  allantois,  is  made  to  come  in 
contact  with  the  external  membrane  of  the  egg  for  purposes  of 
exhalation  and  absorption ;  and  this  can  only  be  accomplished  by 
opening  a  passage  for  it  through  the  external  germinative  layer. 
This  is  done  in  the  following  manner,  by  the  formation  of  the 
amnion. 

Soon  after  the  body  of  the  foetus  has  begun  to  be  formed  by  the 
thickening  of  the  external  layer  of  the  blastodermic  membrane, 
a  double  fold  of  this  external  layer  rises  up  on  all  sides  about 
the  edges  of  the  newly  formed  enabryo ;  so  that  the  body  of  the 
foetus  appears  as  if  sunk  in  a  kind  of  depression,  and  surrounded 
with  a  membranous  ridge  or  embankment,  as  in 
Fig.  190.  The  embryo  (c)  is  here  seen  in  profile, 
with  the  double  membranous  folds,  above  men- 
tioned, rising  up  just  in  advance  of  the  head, 
and  behind  the  posterior  extremity.  It  must  be 
understood,  of  course,  that  the  same  thing  takes 
place  on  the  two  sides  of  the  foetus,  by  the  forma- 
Diagram  of  fecpn-  tiou  of  lateral  folds  simultaneously  with  the 
BATED  Ego;  showing    appearance  of  those  in  front  and  behind.     As  it 

formation  of  amnion. —         ^ i^ 

a.  viteiius.  6.  External    is  thcsc   folds  which   are   dcstincd  to  form  the 
LTbra1e.''TBod7of    amniou,  they  are  called  the  "amniotic  folds." 
embryo   d,rf.  Amniotic        The  amuiotic  folds  contiuue  to  grow,  and  ex- 

folds.    e.  Vitelline  mem-      .        t    .■,  -,  n  jt_i  j         j  ^    j.        ^^ 

^jj^^g  tend  themselves  lorward,  backward  and  laterally, 

until  they  approach  each  other  at  a  point  over 
the  back  of  the  foetus  (Fig.  191),  which  is  termed  the  "amniotic 
umbilicus."  Their  opposite  edges  afterward  actually  come  in  con- 
tact with  each  other  at  this  point,  and  adhere  together,  so  as  to 
shut  in  a  space  or  cavity  (Fig.  191,  b)  between  their  inner  surface 
and  the  body  of  the  foetus.  This  space,  which  is  filled  with  a  clear 
fluid,  is  called  the  amniotic  cavity.  At  the  same  time,  the  intestinal 
canal  has  begun  to  be  formed,  and  the  umbilical  vesicle  has  been 
partially  separated  from  it,  by  the  constriction  of  the  abdominal 
walls  on  the  under  surface  of  the  body. 

There*  now  appears  a  prolongation  or  diverticulum  (Fig.  191,  c) 
o-rowincr  out  from  the  posterior  portion  of  the  intestinal  canal,  and 
following  the  course  of  the  amniotic  fold  which  has  preceded  it ; 
occupying,  as  it  gradually  enlarges  and  protrudes,  the  space  left 


AMNION    AND    ALLANTOIS. 


503 


Fecundated  Eon, 
farther  advanced.  —  a. 
Umbilical  vesicle.  h. 
Amniotic  cavity,  c.  Al- 
laatois. 


vacant  by  the  rising  up  of  the  amniotic  fold.     This  diverticulum 
is  the  commencement  of  the  allantois.     It  is  an  elongated  mem- 
branous sac,  continuous  with  the  posterior  portion  of  the  intestine, 
and  containing  bloodvessels  derived  from  those 
of  the  intestinal  circulation.     The  cavity  of  the 
allantois  is  also  continuous  with  the  cavity  of 
the  intestine. 

After  the  amniotic  folds  have  approached  and 
touched  each  other,  as  already  described,  over 
the  back  of  the  foetus,  at  the  amniotic  umbilicus, 
the  adjacent  surfaces,  thus  brought  in  contact, 
fuse  together,  so  that  the  cavities  of  the   two 
folds,  coming  respectively  from  front  and  rear, 
are  separated  only  by  a  single  membranous  par- 
tition (Fig.  192,  c)  running  from  the  inner  to  the 
outer  lamina  of  the  amniotic  folds.     This  parti- 
tion itself  soon  after  atrophies  and  disappears;  and  the  inner  and 
outer  larainse  become  consequently  separated  from  each  other.    The 
inner  lamina  (Fig.  192,  a)  which  remains  con- 
tinuous with  the  integument  of  the  foetus,  in- 
closing the  body  of  the  embryo  in  a  distinct 
cavity,  is  called  the  amnion  (Fig.  193,  h\  and 
its  cavity  is   known  as  the   amniotic   cavity. 
The  outer  lamina  of  the  amniotic  fold,  on  the 
other  hand  (Fig.  192,  h\  recedes   farther  and 
farther  from  the  inner,  until  it  comes  in  con- 
tact with  the  original  vitelline  membrane,  still 
covering  the  exterior  of  the  egg ;  and  by  con- 
tinued growth  and  expansion  it  at  last  fuses 
with  the  vitelline  membrane  and  unites  with 
its  substance,  so  that  the  two  membranes  form 
but  one.    This  membrane,  formed  by  the  fusion 
and  consolidation  of  two  others,  constitutes  then 
the  external  investing  membrane  of  the  Qgg. 

The  allantois,  during  all  this  time,  is  increas- 
ing in  size  and  vascularity.  Following  the  course  of  the  amniotic 
folds  as  before,  it  insinuates  itself  between  them,  and  of  course  soon 
comes  in  contact  with  the  external  investing  membrane  just  de- 
scribed. It  then  begins  to  expand  laterally  in  every  direction, 
enveloping  more  and  more  the  body  of  the  foetus,  and  bringing  its 
vessels  into  contact  with  the  external  membrane  of  the  egg. 


Fecundated  Ego, 
with  allantois  nearly  com- 
plete.— a.  Inner  lamina  of 
amniotic  fold.  b.  Outer  la- 
mina of  ditto.  c.  Point 
where  the  amniotic  folds 
come  in  contact.  The  allan- 
tois is  seen  penetrating  be- 
tween the  inner  and  outer 
laminse  of  the  amniotic 
folds. 


604 


AMNION    AND    ALLANTOIS. 


Fig.  193. 


Fecundated  Ego,  with 
allantois  fully  formed. — a.  Um- 
bilical vesicle,  b.  Amnion,  c. 
Allantois. 


By  a  continuation  of  the  above  process,  the  allantois  at  last 
grows  to  such  an  extent  as  to  envelope  completely  the  body  of  the 
embryo,  together  with  the  amnion:  its  two 
extremities  coming  in  contact  with  each 
other  and  fusing  together  over  the  back  of 
the  foetus,  just  as  the  amniotic  folds  had 
previously  done.  (Fig.  193.)  It  lines,  there- 
fore, the  whole  internal  surface  of  the  in- 
vesting membrane  with  a  flattened,  vascu- 
lar sac,  the  vessels  of  which  come  from  the 
interior  of  the  body  of  the  foetus,  and  which 
still  communicates  with  the  cavity  of  the 
intestinal  canal. 

It  is  evident,  from  the  above  description, 
that  there  is  a  close  connection  between  the 
formation  of  the  amnion  and  that  of  the  allantois.  For  it  is  only 
in  this  manner  that  the  allantois,  which  is  an  extension  of  the  in- 
ternal layer  of  the  blastodermic  membrane,  can  come  to  be  situated 
outside  the  foetus  and  the  amnion,  and  be  brought  into  relation 
with  external  surrounding  media.  The  two  laminae  of  the  amni- 
otic folds,  in  fact,  by  separating  from  each  other  as  above  described, 
open  a  passage  for  the  allantois,  and  allow  it  to  come  in  contact 
with  the  external  membrane  of  the  egg. 

In  order  to  explain  more  fully  the  physiological  action  of  the 
allantois,  we  shall  now  proceed  to  describe  the  process  of  develop- 
ment, as  it  takes  place  in  the  egg  of  the  fowl. 

In  order  that  the  embryo  may  be  properly  developed  in  any 
case,  it  is  essential  that  it  be  freely  supplied  with  air,  warmth, 
moisture,  and  nourishment.  The  egg  of  the  fowl  contains  already, 
when  discharged  from  the  generative  passages,  a  sufficient  quantity 
of  moisture  and  albuminous  material.  The  necessary  warmth  is 
supplied  by  the  body  of  the  parent  during  incubation ;  while  the 
atmospheric  gases  can  pass  and  repass  through  the  porous  egg- 
shell, and  by  endosmosis  through  the  fibrous  membranes  which 
line  its  cavity. 

When  the  egg  is  first  laid,  the  vitellus,  or  yolk,  is  enveloped  in 
a  thick  layer  of  semi-solid  albumen.  On  the  commencement  of 
incubation,  a  liquefaction  takes  place  in  the  albumen  immediately 
above  that  part  of  the  vitellus  which  is  occupied  by  the  cicatri- 
cula ;  so  that  the  vitellus  rises  or  floats  upward  toward  the  surface 
by  virtue  of  iis  specific  gravity,  and  the  cicatricula  comes  to  be 


DEVELOPMENT    OF    THE    CHICK. 


505 


placed  almost  immediately  underneath  the  lining  membrane  of  the 
egg-shell.  As  the  cicatricula  is  the  spot  from  which  the  process  of 
embryonic  development  commences,  the  body  of  the  young  foetus 
is  by  this  arrangement  placed  in  the  most  favorable  position  for 
the  reception  of  warmth  and  other  necessary  external  influences 
through  the  egg-shell.  The  liquefied  albumen  is  also  absorbed  by 
the  vitelline  membrane,  and  the  vitellus  thus  becomes  larger,  softer, 
and  more  diffluent  than  before  the  commencement  of  incubation. 

As  soon  as  the  circulatory  apparatus  of  the  embryo  has  been 
fairly  formed,  two  minute  arteries  are  seen  to  run  out  from  its 
lateral  edges  and  spread  out  into  the  neighboring  parts  of  the 
blastodermic  membrane,  breaking  up  into  inosculating  branches, 
and  covering  the  adjacent  portions  of  the  vitellus  with  a  plexus  of 
capillary  bloodvessels.  The  space  occupied  in  the  blastodermic 
membrane,  on  the  surface  of  the  vitellus,  by  these  vessels,  is  called 
the  area  vasculosa.     (Fig.  194.)     It  is  of  a  nearly  circular  shape, 


Fig.  194. 


Egg  of  Fowl  during  early  periods  of  incubation  ;  showing  the  body  of  the  embryo,  and  the  area 
vasculosa  partially  covering  the  surface  of  the  vitellus. 

and  is  limited,  on  its  outer  edge,  by  a  terminal  vein  or  sinus,  called 
the  "sinus  terminalis."  The  blood  is  returned  to  the  body  of  the 
foetus  by  two  veins  which  penetrate  beneath  its  edges,  one  near  the 
head  and  one  near  the  tail. 

The  area  vasculosa  tends  to  increase  in  extent,  as  the  develop- 
ment of  the  foetus  proceeds  and  its  circulation  becomes  more  active. 
It  soon  covers  the  upper  half,  or  hemisphere,  of  the  vitellus,  and 
the  terminal  sinus  then  runs  like  an  equator  round  the  middle  of 


506 


AMNION    AND    ALLANTOIS. 


the  vitelline  sphere.  As  the  growth  of  the  vascular  plexus  con- 
tinues, it  passes  this  point,  and  embraces  more  and  more  of  the  in- 
ferior, as  well  as  of  the  superior  hemisphere,  the  vessels  converging 
toward  its  under  surface,  until  at  last  nearly  the  whole  of  the 
vitellus  is  covered  with  a  network  of  inosculating  capillaries. 

The  function  of  the  vessels  of  the  area  vasculosa  is  to  absorb 
nourishment  from  the  cavity  of  the  vitelline  sac.  As  the  albumen 
liquefies  during  the  process  of  incubation,  it  passes  by  endosmosis, 
more  and  more  abundantly,  into  the  vitelline  cavity;  the  whole 
vitellus  growing  constantly  larger  and  more  fluid  in  consistency. 
The  blood  of  the  foetus,  then  circulating  in  the  vessels  of  the  area 
vasculosa,  absorbs  freely  the  oleagino-albuminous  matters  of  the 
vitellus,  and,  carrying  them  back  to  the  foetus  by  the  returning 
veins,  supplies  the  newly-formed  tissues  and  organs  with  abun- 
dance of  nourishment. 

During  this  period  the  amnion  and  the  allantois  have  been  also 
in  process  of  formation.  At  first  the  body  of  the  foetus  lies  upon 
its  abdomen,  as  in  the  cases  previously  described ;  but  as  it  increases 
in  size  it  alters  its  position  so  as  to  lie  more  upon  its  side.  The 
allantois  then,  emerging  from  the  posterior  portion  of  the  abdominal 
cavity,  turns  directly  upward  over  the  body  of  the  foetus,  and  comes 
immediately  in  contact  with  the  shell  membrane.     (Fig.  195.)     It 

Fig.  195. 


Ego  of  Fowl  at  a  more  advanced  period  of  development.  The  body  of  the  foetus  is  enveloped 
by  the  amnion,  and  has  the  umbilical  vesicle  hanging  from  its  under  surface  ;  while  the  vascular 
allantois  is  seen  turning  upward  and  spreading  out  over  the  internal  surface  of  the  shell-membrane. 


then  spreads  out  rapidly,  extending  toward  the  extremities  and 
down  the  sides  of  the  egg,  enveloping  more  and  more  completely 


DEVELOPMENT    OF    THE    CHICK.  507 

the  foetus  and  the  vitelline  sac,  and  taking  the  place  of  the  albumen 
which  has  been  liquefied  and  absorbed. 

It  will  also  be  seen,  by  reference  to  the  figure,  that  the  umbilical 
vesicle  is  at  the  same  time  formed  by  the  separation  of  part  of  the 
vitellus  from  the  abdomen  of  the  chick;  and  the  vessels  of  the  area 
vasculosa,  which  were  at  first  distributed  over  the  vitellus,  now 
ramify,  of  course,  upon  the  surface  of  the  umbilical  vesicle. 

At  last  the  allantois,  by  its  continued  growth,  envelopes  nearly 
the  whole  of  the  remaining  contents  of  the  egg ;  so  that  toward  the 
later  periods  of  incubation,  at  whatever  point  we  break  open  the 
egg,  we  find  the  internal  surface  of  the  shell-membrane  everywhere 
lined  with  a  vascular  membranous  expansion,  supplied  by  arteries 
which  emerge  from  the  abdomen  of  the  fcBtus. 

It  is  easy  to  see,  accordingly,  with  what  readiness  the  absorption 
and  exhalation  of  gases  may  take  place  by  means  of  the  allantois. 
The  air  penetrates  from  the  exterior  through  the  minute  pores  of 
the  calcareous  shell,  and  then  acts  upon  the  blood  in  the  vessels  of 
the  allantois  very  much  in  the  same  manner  that  the  air  in  the  minute 
bronchial  tubes  and  air- vesicles  of  the  lungs  acts  upon  the  blood  in 
the  pulmonary  capillaries.  Examination  of  the  egg,  furthermore, 
at  various  periods  of  incubation,  shows  that  changes  take  place  in 
it  which  are  entirely  analogous  to  the  process  of  respiration. 

The  egg,  in  the  first  place,  during  its  development,  loses  water  by 
exhalation.  This  exhalation  is  not  a  simple  efl'ect  of  evaporation, 
but  is  the  result  of  the  nutritive  changes  going  on  in  the  interior 
of  the  egg ;  since  it  does  not  take  place,  except  in  a  comparatively 
slight  degree,  in  unimpregnated  eggs,  or  in  those  which  are  not  in- 
cubated, though  they  may  be  freely  exposed  to  the  air.  The  ex- 
halation of  fluid  is  also  essential  to  the  processes  of  development, 
for  it  has  often  been  found,  in  hatching  eggs  by  artificial  warmth, 
that  if  the  air  of  the  chamber  in  which  they  are  inclosed  become 
unduly  charged  with  moisture,  so  as  to  retard  or  prevent  further 
exhalation,  the  eggs  readily  become  spoiled,  and  the  development 
of  the  embryo  is  arrested.  The  loss  of  weight  during  natural  incu- 
bation, principally  due  to  the  exhalation  of  water,  has  been  found  by 
Baudrimont  and  St.  Ange'  to  be  over  15  per  cent,  of  the  entire 
weight  of  the  egg. 

Secondly,  the  egg  absorbs  oxygen  and  exhales  carbonic  acid. 
The  two  observers  mentioned  above,  ascertained  that  during  eigh- 

'  Du  Developpement  du  Foetus.     Paris,  1850,  p.  143. 


508  AMNION    AND    ALLANTOIS. 

teen  days'  incubation,  the  egg  absorbed  nearly  2  per  cent,  of  its 
weight  of  oxygen,  while  the  quantity  of  carbonic  acid  exhaled  from 
the  sixteenth  to  the  nineteenth  day  of  incubation  amounted  to  no 
less  than  3  grains  in  the  twenty-four  hours.'  It  is  curious  to  observe, 
also,  that  in  the  egg  during  incubation,  as  well  as  in  the  adult 
animal,  more  oxygen  is  absorbed  than  is  returned  by  exhalation 
under  the  form  of  carbonic  acid. 

It  is  evident,  therefore,  that  a  true  respiration  takes  place  by 
means  of  the  allantois,  through  the  membranes  of  the  shell. 

The  allantois,  however,  is  not  simply  an  organ  of  respiration ;  it 
takes  part  also  in  the  absorption  of  nutritious  matter.  As  the  pro- 
cess of  development  advances,  the  skeleton  of  the  young  chick,  at 
first  entirely  cartilaginous,  begins  to  ossify.  The  calcareous  mat- 
ter, necessary  for  this  ossification,  is,  in  all  probability,  derived  from 
the  shell.  The  shell  is  certainly  lighter  and  more  fragile  toward 
the  end  of  incubation  than  at  first;  and,  at  the  same  time,  the  cal- 
careous ingredients  of  the  bones  increase  in  quantity.  The  lime- 
salts,  requisite  for  the  process  of  ossification,  are  apparently  ab- 
sorbed from  the  shell  by  the  vessels  of  the  allantois,  and  by  them 
transferred  to  the  skeleton  of  the  growing  chick ;  so  that,  in  the 
same  proportion  that  the  former  becomes  weaker,  the  latter  grows 
stronger.  This  diminution  in  density  of  the  shell  is  connected  not 
only  with  the  development  of  the  skeleton,  but  also  with  the  final 
escape  of  the  chick  from  the  egg.  This  deliverance  is  accomplished 
mostly  by  the  movements  of  the  chick  itself,  which  become,  at  a 
certain  period,  sufficiently  vigorous  to  break  out  an  opening  in  the 
attenuated  and  weakened  egg-shell.  The  first  fracture  is  generally 
accomplished  by  a  stroke  from  the  end  of  the  bill ;  and  it  is  pre- 
cisely at  this  point  that  the  solidification  of  the  skeleton  is  most 
advanced.  The  egg-shell  itself,  therefore,  which  at  first  only  serves 
for  the  protection  of  the  imperfectly-formed  embryo,  afterward 
lurnishes  the  materials  which  are  used  to  accomplish  its  own  demo- 
lition, and  at  the  same  time  to  effect  the  escape  of  the  fully  deve- 
loped foetus. 

Toward  the  latter  periods  of  incubation,  the  allantois  becomes 
more  and  more  adherent  to  the  internal  surface  of  the  shell-mem- 
brane. At  last,  when  the  chick,  arrived  at  the  full  period  of  de- 
velopment, escapes  from  its  confinement,  the  allantoic  vessels  are 
torn  off  at  the  umbilicus ;  and  the  allantois  itself,  cast  off  as  a  use- 

'  Op.  cit.,  pp.  138  and  149. 


DEVELOPMENT    OF    THE    CHICK.  509 

less  and  effete  organ,  is  left  behind  in  the  cavity  of  the  abandoned 
egg-shell.  The  allantois  is,  therefore,  strictly  speaking,  a  foetal 
organ.  Developed  as  an  accessory  structure  from  a  portion  of  the 
intestinal  canal,  it  is  exceedingly  active  and  important  during  the 
middle  and  latter  periods  of  incubation ;  but  when  the  chick  is 
completely  formed,  and  has  become  capable  of  carrying  on  an  in- 
dependent existence,  both  the  amnion  and  the  allantois  are  detached 
and  thrown  off  as  obsolete  structures,  their  place  being  afterward 
supplied  by  other  organs  belonging  to  the  adult  condition. 


510      DEVELOPMENT    OF    THE    EGG    IN    HUMAN    SPECIES. 


CHAPTER    X, 


DEVELOPMENT    OF    THE    EGG    IN    THE    HUMAN 
SPECIES.— FORMATION   OF    THE    CHORION. 

We  have  already  described,  in  a  preceding  chapter,  the  manner 
in  which  the  outer  lamina  of  the  amniotic  fold  becomes  adherent 
to  the  adjacent  surface  of  the  vitelline  membrane,  so  as  to  form 
with  it  but  a  single  layer ;  and  in  which  these  two  membranes,  thus 
fused  and  united  with  each  other,  form  at  that  time  the  single  ex- 
ternal investing  membrane  of  the  egg.  The  allantois,  in  its  turn, 
afterward  comes  in  contact  with  the  investing  membrane,  and  lies 
immediately  beneath  it,  as  a  double  vascular  membranous  sac.  In 
the  egg  of  the  human  subject  the  development  of  the  membranes, 
though  carried  on  essentially  upon  the  same  plan  with  that  which 
we  have  already  described,  undergoes,  in  addition,  some  further 
modifications,  which  we  shall  now  proceed  to  explain. 

The  first  of  these  peculiarities  is  that  the  allantois,  after  spread- 
ing out  upon  the  inner  surface  of 
Fig.  196.  the  external  investing  membrane, 

adheres  to,  and  fuses  with  it,  just 
as  the  outer  lamina  of  the  amni- 
otic fold  has  previously  fused 
with  the  vitelline  membrane.  At 
the  same  time,  the  two  layers  be- 
longing to  the  allantois  itself  also 
come  in  contact  and  fuse  toge- 
ther ;  so  that  the  cavity  of  the 
allantois  is  obliterated,  and  instead 
of  forming  a  membranous  sac  con- 
taining fluid,  this  organ  is  convert- 
ed into  a  simple  vascular  membrane. 
(Fig.  196.)  This  membrane, 
moreover,  being,  after  a  time, 
thoroughly  fused  and  united  with  the  two  which  have  preceded  it, 
takes  the  place  which  was  previously  occupied  by  them.     It  is  then 


HrMAN  Ovum,  about  the  end  of  the  first 
month;  showing  formation  of  chorion.  —  1. 
Umbilical  vesicle.     2.  Amnion.     3.  Chorion. 


FOKMATION    OF    THE    CHORION.  511 

termed  the  cJwrion,  and  thus  becomes  the  sole  external  investing 
Tnembrane  of  the  egg. 

We  find,  therefore,  that  the  chorion,  that  is,  the  external  coat  or 
investment  of  the  egg,  is  formed  successively  by  three  distinct  mem- 
branes, as  follows:  first,  the  original  vitelline  membrane;  secondly, 
the  outer  lamina  of  the  amniotic  fold;  and,  thirdly,  the  allantois; 
the  last  predominating  over  the  two  former  by  the  rapidity  of  its 
growth,  and  absorbing  them  into  its  substance,  so  that  they  become 
finally  completely  incorporated  with  its  texture. 

It  is  easy  to  see,  also,  how,  in  consequence  of  the  above  process, 
the  body  of  the  foetus,  in  the  human  egg,  becomes  inclosed  in  two 
distinct  membranes,  viz.,  the  amnion,  which  is  internal  and  conti- 
nuous with  the  foetal  integument,  and  the  chorion,  which  is  external 
and  supplied  with  vessels  from  the  cavity  of  the  abdomen.  The 
umbilical  vesicle  is,  of  course,  situated  between  the  two ;  and  the  rest 
of  the  space  between  the  chorion  and  the  amnion  is  occupied  by 
a  semi-fluid  gelatinous  material,  somewhat  similar  in  appearance 
to  that  of  the  vitreous  body  of  the  eye. 

The  obliteration  of  the  cavity  of  the  allantois  takes  place  very 
early  in  the  human  subject,  and,  in  fact,  keeps  pace  almost  entirely 
with  the  progress  of  its  growth  ;  so  that  this  organ  never  presents, 
in  the  human  egg,  the  appearance  of  a  hollow  sac,  filled  with 
fluid,  but  rather  that  of  a  flattened  vascular  membrane,  enveloping 
the  body  of  the  foetus,  and  forming  the  external^membrane  of  the 
egg.  Notwithstanding  this  difference,  however,  the  chorion  of  the 
human  subject  is,  in  respect  to  its  mode  of  formation,  the  same 
thing  with  the  allantois  of  the  lower  animals;  its  chief  peculiarity 
consisting  in  the  fact  tbat  its  opposite  surfaces  are  adherent  to  each 
other,  instead  of  remaining  separate  and  inclosing  a  cavity  filled 
with  fluid. 

The  next  peculiarity  of  the  human  chorion  is,  that  it  becomes 
shaggy.  Even  while  the  egg  is  still  very  small,  and  has  but  recently 
found  its  way  into  the  uterine  cavity,  its  exterior  is  already  seen 
to  be  covered  with  little  transparent  prominences,  like  so  many 
villi  (Fig.  196),  which  increase  the  extent  of  its  surface,  and  assist 
in  the  absorption  of  fluids  from  without.  The  villi  are  at  this  time 
quite  simple  in  form,  and  altogether  homogeneous  in  structure. 

As  the  egg  increases  in  size,  the  villi  rapidly  elongate,  and  be- 
come divided  and  ramified  by  the  repeated  budding  and  sprouting  of 
lateral  offshoots  from  every  part.  After  this  process  of  growth  has 
gone  on  for  some  time,  the  external  surface  of  the  chorion  presents 


512      DEVELOPMENT    OF    THE    EGG    IN    HUMAN    SPECIES. 


a  uniformly  velvety  or  shaggy  appearance,  owing  to  its  being  co- 
vered everywhere  with  these  tufted  and  compound  villosities. 

The  villosities  themselves,  when  examined  by  the  microscope, 
have  an  exceedingly  well  marked  and  characteristic  appearance. 
(Fig.  197.)     They  originate  from  the  surface  of  the  chorion  by  a 

somewhat  narrow  stem,  and  divide 
into  a  multitude  of  secondary  and 
tertiary  branches,  of  varying  size 
and  figure;  some  of  them  slender 
and  filamentous,  others  club-shaped, 
many  of  them  irregularly  swollen  at 
various  points.  All  of  them  termi 
nate  by  rounded  extremities,  giving 
to  the  whole  tuft  a  certain  resem- 
blance to  some  varieties  of  sea- weed. 
The  larger  trunks  and  branches  of 
,r-"''^\>\T^'"°'''/'S7/<''  '^-^^^^'"■'^^a?^  ^^®  villosity  are  seen  to  contain  nu- 
ilCr^^N^^^X/^^^^       merous  minute  nuclei,  imbedded  in 

a  nearly  homogeneous,  or  finely  gra- 
nular substratum.  The  smaller  ones 
appear,  under  a  low  magnifying 
power,  simply  granular  in  texture. 

These  villi  are  altogether  peculiar 
in  appearance,  and  quite  unlike  any 
other  structure  which  may  be  met  with  in  the  body.  Wherever  we 
find,  in  the  uterus,  any  portion  of  a  membrane  having  villosities 
like  these,  we  may  be  sure  that  pregnancy  has  existed ;  for  such 
villosities  can  only  belong  to  the  chorion,  and  the  chorion  itself  is 
a  part  of  the  foetus.  It  is  developed,  as  we  have  seen,  as  an  out- 
growth from  the  intestinal  canal,  and  can  only  exist,  accordingly, 
as  a  portion  of  the  fecundated  egg.  The  presence  of  portions  of  a 
shaggy  chorion  is  therefore  as  satisfactory  proof  of  the  existence 
of  pregnancy,  as  if  we  had  found  the  body  of  the  foetus  itself. 

While  the  villosities  which  we  have  just  described  are  in  pro- 
cess of  formation,  the  allantois  itself  has  completed  its  growth,  and 
has  become  converted  into  a  permanent  chorion.  The  bloodvessels 
coming  from  the  allantoic  arteries  accordingly  ramify  over  the 
chorion,  and  supply  it  with  a  tolerably  abundant  vascular  network. 
The  growth  of  the  foetus,  moreover,  at  this  time,  has  reached  such 
a  state  of  activity,  that  it  requires  to  be  supplied  with  nourishment 
by  vascular  absorption,  instead  of  the  slow  process  of  imbibition, 


Compound  villosity  of  Human  Cho- 
EION,  ramified  extremity.  From  a  three 
mouths'  foetus.     Magnified  .'50  diameters. 


FORMATION    OF    THE    CHORION. 


513 


Fig.  198. 


Extrernily  of  vrLLOsiTT  of 
Chorion,  more  highly  magni- 
fied ;  showing  the  ai-rangement  of 
bloodvessels  in  its  interior. 


which  has  heretofore  taken  place  through  the  comparatively  incom- 
})lete  and  structureless  villi  of  the  cho- 
rion. The  capillary  vessels,  accordingly, 
with  which  the  chorion  is  supplied,  begin 
to  penetrate  into  the  substance  of  its  vil- 
losities.  They  enter  the  base  or  stem  of 
each  villosity,  and,  following  every  divi- 
sion of  its  compound  ramifications,  finally 
reach  its  rounded  extremities.  Here 
they  turn  upon  themselves  in  loops  (Fig. 
198),  like  the  vessels  in  the  papillae  of 
the  skin,  and  retrace  their  course,  to  unite 
finally  with  the  venous  trunks  of  the 
chorion. 

The  villi  of  the  chorion  are  therefore 
very  analogous  in  structure  to  those  of 
the  intestine;  and  their  power  of  absorp- 
tion, as  in  other  similar  instances,  corresponds  with  the  abundance 
of  their  ramifications,  and  the  extent  of  their  vascularity. 

It  must  be  remembered,  also,  that  these  vessels  all  come  from  the 
abdomen  of  the  foetus ;  and  that  whatever  substances  are  taken  up 
by  them  are  transported  directly  to  the  interior  of  the  embryo,  and 
used  for  the  nourishment  of  its  tissues.  The  chorion,  therefore,  as 
soon  as  its  villi  and  bloodvessels  are  completely  developed,  becomes 
an  exceedingly  active  organ  in  the  nutrition  of  the  foetus;  and  con- 
stitutes, in  fact,  the  only  means  by  which,  new  material  can  be  in- 
troduced from  without. 

The  existence  of  this  general  vascularity  of  the  chorion  affords 
also,  as  Coste  was  the  first  to  point  out,  a  striking  indication 
that  this  membrane  is  in  reality  identical  with  the  allantois  of  the 
lower  animals.  If  the  reader  will  turn  back  to  the  illustrations  of 
the  formation  of  the  amnion  and  allantois  (Chap.  IX.),  he  will  see 
that  the  first  chorion  or  investing  membrane  is  formed  exclusively 
by  the  vitelline  membrane,  which  is  never  vascular  and  cannot  be- 
come so  by  itself,  since  it  has  no  direct  connection  with  the  foetus. 
The  second  chorion  is  formed  by  the  union  of  the  vitelline  mem- 
brane with  the  outer  lamina  of  the  amniotic  fold.  Both  laminas 
of  the  amniotic  fold  are  at  first  vascular,  since  they  are  portions  of 
the  external  blastodermic  layer,  and  derive  their  vessels  from  the 
integument  of  the  foetus.  But  after  the  outer  lamina  has  become 
completely  separated  from  the  inner,  by  the  disappearance  of  the 
33 


514      DEVELOPMENT    OF    THE    EGG    IN    HUMAN    SPECIES. 


partition  which  for  a  time  connected  the  two  with  each  other  (Fig. 
192,  c),  this  source  of  vascular  supply  is  cut  off;  and  the  second  cho- 
rion cannot,  therefore,  remain  vascular  after  that  period.  But  the 
third  or  permanent  chorion,  that  is,  the  allantois,  derives  its  ves- 
sels directly  from  those  of  the  foetus,  and  retains  its  connection  with 
them  during  the  whole  period  of  gestation.  A  chorion,  therefore, 
which  is  universally  and  permanently  vascular,  can  be  no  other 
tlian  the  allantois,  converted  into  an  external  investing  membrane 
of  the  egg. 

Thirdly,  the  chorion,  which  is  at  one  time,  as  we  have  seen,  every- 
where villous  and  shaggy,  becomes  afterward  partially  bald.  This 
change  begins  to  take  place  about  the  end  of  the  second  month. 
It  commences  at  a  point  opposite  the  situation  of  the  foetus  and  the 
insertion  of  the  foetal  vessels.  The  villosities  in  this  region  cease 
growing;  and  as  the  entire  egg  continues  to  enlarge,  the  villosities 
at  the  point  indicated  fail  to  keep  pace  with  its  growth,  and  with 
the  progressive  expansion  of  the  chorion.  They  accordingly  be- 
come at  this  part  thinner  and  more  scattered,  leaving  the  surface 
of  the  chorion  comparatively  smooth  and  bald.  This  baldness  in- 
creases in  extent  and  becomes  more  and  more  complete,  spreading 
and  advancing  over  the  adjacent  portions  of  the  chorion,  until  at 
least  two-thirds  of  its  surface  have  become  nearly  or  quite  destitute 
of  villosities. 

.'  At  the  opposite  point  of  the  surface  of  the  egg,  however,  that 

portion,  namely,  which  corre- 
sponds with  the  insertion  of  the 
foetal  vessels,  the  villosities, 
instead  of  becoming  atrophied, 
continue  to  grow ;  and  this 
portion  of  the  chorion  becomes 
even  more  shaggy  and  thickly 
set  than  before.  The  conse- 
quence is  that  the  chorion 
afterward  presents  a  very  dif- 
ferent appearance  at  different 
portions  of  its  surface.  (Fig. 
199.)    The  greater  part  of  it  is 

HnMAN  OvcM  at  end  of  third  month;  showing       g^^yQ^Ji  .    ^ut  a  Certain  portion, 
placental  portion  of  the  chorion  fully  formed.  i   •     1      £• 

constituting  about  one-third  or 
the  whole,  is  covered  with  a  soft  and  spongy  mass  of  long,  thickly- 
set,  compound  villosities.     It  is  this  thickened  and  shaggy  portion, 


Fig.  199. 


FORMATION    OF    THE    CHORION.  515 

which  is  afterward  concerned  in  the  formation  of  the  placenta : 
while  the  remaining  smooth  portion  continues  to  be  known  under 
the  name  of  the  chorion.  The  placental  portion  of  the  chorion 
becomes  distinctly  limited  and  separated  from  the  remainder  by 
about  the  end  of  the  third  month. 

The  vascularity  of  the  chorion  keeps  pace,  in  its  different  parts 
respectively,  with  the  atrophy  and  development  of  its  villosities. 
As  the  villosities  shrivel  and  disappear  over  a  part  of  its  extent, 
the  looped  capillary  vessels,  which  they  at  first  contained,  disappear 
also ;  so  that  the  smooth  portion  of  the  chorion  shows  afterward 
only  a  few  straggling  vessels  running  over  its  surface,  and  does  not 
contain  any  abundant  capillary  plexus.  In  the  thickened  portion, 
on  the  other  hand,  the  vessels  lengthen  and  ramify  to  an  extent  cor- 
responding with  that  of  the  villosities  in  which  they  are  situated. 
The  allantoic  arteries,  coming  from  the  abdomen  of  the  foetus,  enter 
the  villi,  and  penetrate  through  their  whole  extent ;  forming,  at  the 
placental  portion  of  the  chorion,  a  mass  of  tufted  and  ramified  vas- 
cular loops,  while  over  the  rest  of  the  membrane  they  are  merely 
distributed  as  a  few  single  and  scattered  vessels. 

The  chorion,  accordingly,  is  the  external  investing  membrane  of 
the  Qgg^  produced  by  the  consolidation  and  transformation  of  the 
allantois.  The  placenta,  furthermore,  so  far  as  it  has  now  been 
described,  is  evidently  a  part  of  the  chorion ;  that  part,  namely, 
which  is  thickened,  shaggy  and  vascular,  while  the  remainder  is 
comparatively  thin,  smooth,  and  membranous. 


516        DEVELOPMENT    OF    UTERINE    MUCOUS    MEMBRANE. 


CHAPTER    XI. 

DEVELOPMENT  OF  UTERINE  MUCOUS  MEMBRANE.— 
FORMATION   OF   TUE   DECIDUA. 

In  fish,  reptiles,  and  birds,  tlae  egg  is  either  provided  with  a  sup- 
ply of  nutritious  material  contained  within  its  membranes,  or  it  is 
so  placed,  after  its  discharge  from  the  body  of  the  parent,  that  it 
can  absorb  these  materials  from  without.  Thus,  in  the  egg  of  the 
bird,  the  young  embryo  is  supported  upon  the  albuminous  matter 
deposited  around  the  vitellus ;  while  in  the  frog  and  fish,  moisture, 
oxygen,  saline  substances,  &c.,  are  freely  imbibed  from  the  water 
in  which  the  egg  is  placed. 

But  in  the  quadrupeds,  as  well  as  in  the  human  species,  the  egg 
is  of  minute  size,  and  the  quantity  of  nutritious  matter  which  it 
contains  is  sufficient  to  last  only  for  a  very  short  time.  Moreover, 
the  development  of  the  foetus  takes  place  altogether  within  the  body 
of  the  female,  and  no  supply,  therefore,  can  be  obtained  directly 
from  the  external  media.  In  these  instances,  accordingly,  the  mu- 
cous membrane  of  the  uterus,  which  is  found  to  be  unusually 
developed  and  increased  in  functional  activity  during  the  period  of 
gestation,  becomes  a  source  of  nutrition  for  the  fecundated  egg. 
The  uterine  mucous  membrane,  thus  developed  and  hypertrophied, 
is  known  by  the  name  of  the  Decidua. 

It  has  received  this  name  because,  as  we  shall  hereafter  see,  it 
becomes  exfoliated  and  thrown  off,  at  the  same  time  that  the  egg 
itself  is  finally  discharged. 

The  mucous  membrane  of  the  body  of  the  uterus,  in  the  unimpreg- 
nated  condition,  is  quite  thin  and  delicate,  and  presents  a  smooth 
and  slightly  vascular  internal  surface.  There  is,  moreover,  no  layer 
of  submucous  cellular  tissue  between  it  and  the  muscular  substance 
of  the  uterus ;  so  that  the  mucous  membrane  cannot  here,  as  in 
most  other  organs,  be  easily  dissected  up  and  separated  from  the 
subjacent  parts.  The  structure  of  the  mucous  membrane  itself, 
however,  is  sufficiently  well  marked   and  readily  distinguishable 


FORMATION    OF    THE    DECIDUA. 


517 


Fig.  200. 


Uterine  MrroFs  Membrakk,  as 
seeu  in  vertical  section. — a.  Free  surface. 
6.  Attached  surface. 


from  that  of  other  parts.  It  consists,  throughout,  of  minute  tubular 
follicles,  ranged  side  by  side,  and  running  perpendicularly  to  the 
free  surface  of  the  mucous  membrane.  (Fig.  200.)  Near  this  free 
surface,  they  are  nearly  straight ;  but 
toward  the  deeper  surface  of  the  mu- 
cous membrane,  where  they  terminate 
in  blind  extremities,  or  cul-de-sacs, 
they  become  more  or  less  wavy  or 
spiral  in  their  cour.se.  The  tubules 
are  about  yig  of  an  inch  in  diameter, 
and  are  lined  throughout  with  co- 
lumnar epithelium.  (Fig.  201.)  They 
occupy  the  entire  thickness  of  the  ute- 
rine mucous  membrane,  their  closed 
extremities  resting  upon  the  subjacent 

muscular  tissue,  while  their  mouths  open  into  the  cavity  of  the  ute- 
rus. A  few  fine  bloodvessels  penetrate  the  mucous  membrane  from 
below,  and,  running  upward 

between  the  tubules,  encircle  Fig-  201. 

their  superficial  extremities 
with  a  capillary  network. 
There  is  no  areolar  tissue  in 
the  uterine  mucous  mem- 
brane, but  only  a  small  quan- 
tity of  spindle-shaped  fibro- 
plastic fibres,  scattered  be- 
tween the  tubules. 

As  the  fecundated  egg  is 
about  to  descend  into  the 
cavity  of  the  uterus,  the  mu- 
cous membrane,  above  de- 
scribed, takes  on  an  increased 

.     .  Uterixe  Tubules,  from  mucous  membrane  of 

activity     of     growth     and     an      unimpregnated  human  uterus. 

unusual  development.  It  be- 
comes tumefied  and  vascular;  and  as  it  increases  in  thickness,  it 
projects,  in  rounded  eminences  or  convolutions,  into  the  uterine 
cavity.  (Fig.  202.)  In  this  process,  the  tubules  of  the  uterus  in- 
crease in  length,  and  also  become  wider;  so  that  their  open  mouths 
may  be  readily  seen  by  the  naked  e3^e  upon  the  uterine  surface,  as 
numerous  minute  perforations.  The  bloodvessels  of  the  mucous 
membrane  also  enlarge  and  multiply,  and  inosculate  freely  with 


518        DEVELOPMENT    OF    UTERINE    MUCOUS    MEMBRANE. 

each  other;  so  that  the  vascular  network  encircling  the  tubules  be- 
comes more  extensive  and  abundant. 

The  internal  surface  of  the  uterus,  accordingly,  after  this  process 
has  been  for  some  time  going  on,  presents  a  thick,  rich,  soft,  vas- 
cular, and  velvety  lining,  quite  different  from  that  which  is  to  be 
found  in  the  unimpregnated  condition.  In  consequence  of  this 
difference,  the  lining  membrane  of  the  uterus,  in  the  impregnated 
condition,  was  formerly  supposed  to  be  an  entirely  new  product, 
thrown  out  by  exudation  from  the  uterine  surface,  and  analogous, 
in  this  respect,  to  the  inflammatory  exudations  of  croup  and  pleu- 
risy. It  is  now  known,  however,  to  be  no  other  than  the  mucous 
membrane  of  the  uterus  itself,  thickened  and  hypertrophied  to  an 
extraordinary  degree,  but  still  retaining  all  its  natural  connections 
and  its  original  anatomical  structure. 

The  hypertrophied  mucous  membrane,  above  described,  consti- 
tutes the  Decidua  vera.  Its  formation  is  confined  altogether  to  the 
body  of  the  uterus,  the  mucous  membrane  of  the  cervix  taking  no 
part  in  the  process,  but  retaining  its  original  appearance.  The 
decidua  vera,  therefore,  commences  above,  at  the  orifices  of  the 
Fallopian  tubes,  and  ceases  below,  at  the  situation  of  the  os  inter- 
num. The  cavity  of  the  cervix,  at  this  time,  begins  to  be  filled 
with  an  abundant  secretion  of  its  peculiarly  viscid  mucus,  which 
blocks  up,  more  or  less  completely,  its  passage,  and  protects  the 
internal  cavity.  But  there  is  no  membranous  partition  at  this  time 
covering  the  os  internum,  and  the  mucous  membranes  of  the  cervix 
and  of  the  body  of  the  uterus,  though  very  different  in  appearance, 
are  still  perfectly  continuous  with  each  other.  When  we  cut  open 
the  cavity  of  the  uterus,  therefore,  in  this  condition,  we  find  its 
internal  surface  lined  with  the  decidua  vera,  with  the  opening  of 
the  OS  internum  below  and  the  orifices  of  the  Fallopian  tubes  above, 
perfectly  distinct,  and  in  their  natural  positions.  (Fig.  202.) 

As  the  fecundated  egg^  in  its  journey  from  above  downward, 
passes  the  lower  orifice  of  the  Fallopian  tube,  it  insinuates  itself 
between  the  opposite  surfaces  of  the  uterine  mucous  membrane, 
and  becomes  soon  afterward  lodged  in  one  of  the  furrows  or  de- 
pressions between  the  projecting  convolutions  of  the  decidua. 
(Fig.  202.)  It  is  at  this  situation  that  an  adhesion  is  subsequently 
to  take  place  between  the  external  membranes  of  the  egg,  on  the 
one  hand,  and  the  uterine  decidua  on  the  other.  Now  at  the  point 
where  the  egg  becomes  fixed  and  entangled,  as  above  stated,  a  still 
more  rapid  development  than  before  takes  place  in  the  uterine 


FORMATION    OF    THE    DECIDUA. 


51^ 


mucous  membrane.  Its  projecting  folds  begin  to  grow  up  around 
the  egg  in  such  a  manner  as  to  partially  inclose  it  in  a  kind  of 
circumvallation  of  the  decidua,  and  to  shut  it  off",  more  or  less  com- 


Fiff.  202. 


Fig.  203. 


Impreuxatep  Uterus;  showing 
formation  of  decidua.  The  decidua  is 
represented  in  black  ;  and  the  egg  is 
!*een,  at  the  fundus  of  the  uterus,  engaged 
between  two  of  its  projecting  convolu- 
tions. 


Impregnated  Uterus,  with  pro- 
jecting folds  of  decidua  growing  up 
around  the  egg.  The  narrow  opening, 
where  the  edges  of  the  folds  approach 
each  other,  is  seen  over  the  most  promi- 
nent portion  of  the  egg. 


Fi?.  204. 


pletely,  from  the  general  cavity  of  the  uterus.  (Fig.  203.)  The 
egg  is  thus  soon  contained  in  a  special  cavity  of  its  own,  which 
still  communicates  for  a  time  with  the  general  cavity  of  the  uterus 
by  a  small  opening,  situated  over  its  most  prominent  portion,  which 
is  known  as  the  "decidual  umbilicus."  As  the  above  process  of 
growth  goes  on,  this  opening  becomes  narrower  and  narrower,  while 
the  projecting  folds  of  decidua  approach  each  other  over  the  sur- 
face of  the  egg.  At  last  these  folds  actually  touch  each  other  and 
unite,  forming  a  kind  of  cicatrix  which 
remains  for  a  certain  time,  to  mark  the 
situation  of  the  original  opening. 

When  the  development  of  the  uterus  and 
its  contents  has  reached  this  point  (Fig. 
204),  it  will  be  seen  that  the  egg  is  com- 
pletely inclosed  in  a  distinct  cavity  of  its 
own ;  being  everywhere  covered  with  a 
decidual  layer  of  new  formation,  which 
has  thus  gradually  enveloped  it,  and  by 
which  it  is  concealed  from  view  when  the 
uterine  cavity  is  laid  open.  This  newly 
formed  layer  of  decidua,  enveloping,  as 

,  1-111  •         •  •  n     showing  egg  completely  inclosed 

above  aescribea,  the  projecting  portion  oi    by  decidua  reflexa. 


Impregnated     Uterus; — 


520        DEVELOPMENT    OF    UTERINE    MUCOUS    MEMBRANE. 

the  egg,  is  called  the  Decidua  refiexa ;  because  it  is  reflected  over 
the  egg,  by  a  continuous  growth  from  the  general  surface  of  the 
uterine  mucous  membrane.  The  orifices  of  the  uterine  tubules,  ac- 
cordingly, in  consequence  of  the  manner  in  which  the  decidua 
reflexa  is  formed,  will  be  seen  not  only  on  its  external  surface,  or 
that  which  looks  toward  the  cavity  of  the  uterus,  but  .also  on  its 
internal  surface,  or  that  which  looks  toward  the  egg. 

The  decidua  vera,  therefore,  is  the  original  mucous  membrane 
lining  the  surface  of  the  uterus;  while  the  decidua  reflexa  is  a  new 
formation,  which  has  grown  up  round  the  egg  and  inclosed  it  in  a 
distinct  cavity. 

If  abortion  occur  at  this  time,  the  mucous  membrane  of  the 
uterus,  that  is,  the  decidua  vera,  is  thrown  off",  and  of  course  brings 
away  with  it  the  egg  and  decidua  reflexa.  On  examining  the  mass 
discharged  in  such  an  abortion,  the  egg  will  accordingly  be  found 
imbedded  in  the  substance  of  the  decidual  membrane.  One  side 
of  this  membrane,  where  it  has  been  torn  away  from  its  attachment 
to  the  uterine  walls,  is  ragged  and  shaggy;  the  other  side,  corres- 
ponding to  the  cavity  of  the  uterus,  is  smooth  or  gently  convoluted, 
and  presents  very  distinctly  the  orifices  of  the  uterine  tubules; 
while  the  egg  itself  can  only  be  extracted  by  cutting  through  the 
decidual  membrane,  either  from  one  side  or  the  other,  and  opening 
in  this  way  the  special  cavity  in  which  it  has  been  inclosed. 

During  the  formation  of  the  decidua  reflexa,  the  entire  egg,  as 
well  as  the  body  of  the  uterus  which  contains  it,  has  considerably 
enlarged.  That  portion  of  the  uterine  mucous  membrane  situated 
immediately  underneath  the  egg,  and  to  which  the  egg  first  became 
attached,  has  also  continued  to  increase  in  thickness  and  vascu- 
larity. The  remainder  of  the  decidua  vera,  however,  ceases  to 
grow  as  rapidly  as  before,  and  no  longer  keeps  pace  with  the  in- 
creasing size  of  the  egg  and  of  the  uterus.  It  is  still  very  thick  and 
vascular  at  the  end  of  the  third  month ;  but  after  that  period  it 
becomes  comparatively  thinner  and  less  glandular  in  appearance, 
while  the  unusual  activity  of  growth  and  development  is  concen- 
trated in  the  egg,  and  in  that  portion  of  the  uterine  mucous  mem- 
brane which  is  in  immediate  contact  with  it. 

Let  us  now  see  in  what  manner  the  egg  becomes  attached  to  the 
decidual  membrane,  so  as  to  derive  from  it  the  requisite  supply  of 
nutritious  material.  It  must  be  recollected  that,  while  the  above 
changes  have  been  taking  place  in  the  walls  of  the  uterus,  the  for- 
mation of  the  embryo  in  the  egg,  and  the  development  of  the 


FORMATION    OF    THE    DECIDUA. 


521 


Fiff.  205. 


amnion  and  chorion  have  been  going  on  sinnultaneously.  Soon 
after  the  entrance  of  the  egg  into  the  uterine  cavity,  its  external 
investing  membrane  becomes  covered  with  projecting  filaments,  or 
villosities,  as  previously  described,  (Chap.  X.)  These  villosities, 
which  are  at  first,  as  we  have  seen,  solid  and  non-vascular,  insinuate 
themselves,  as  they  grow,  into  the  uterine  tubules,  or  between  the 
folds  of  the  decidual  surface  with  which  the  egg  is  in  contact,  pene- 
trating in  this  way  into  little  cavities  or  follicles  of  the  uterine 
mucous  membrane,  formed  either  from  the  cavities  of  the  tubules 
themselves,  or  by  the  adjacent  surfaces  (>f  minute  projecting  folds. 
When  the  formation  of  the  decidua  reflexa  is  accomplished,  the 
chorion  has  already  become  uniformly 
shaggy;  and  its  villosities,  spreading  in  all 
directions  from  its  external  surface,  pene- 
trate everywhere  into  the  follicles  above  de- 
scribed, both  of  the  decidua  vera  underneath 
it,  and  the  contiguous  surface  of  the  decidua 
reflexa  with  which  it  is  covered.  (Fig.  206.) 
In  this  way  the  egg  becomes  entangled 
with  the  decidua,  and  cannot  then  be  rea- 
dily separated  from  it,  without  rupturing 
some  of  the  filaments  which  have  grown 
from  its  surface,  and  have  been  received 
into  the  cavity  of  the  follicles.  The  nu- 
tritious fluids,  exuded  from  the  soft  and 
glandular  textures  of  the  decidua,  are  now 
readily  imbibed  by  the  villosities  of  the  chorion;  and  a  more  rapid 
supply  of  nourishment  is  thus  provided,  corresponding  in  abun- 
dance with  the  increased  and  increasing  size  of  the  egg. 

Very  soon,  however,  a  still  greater  activity  of  absorption  be- 
comes necessary ;  and,  as  we  have  seen  in  a  preceding  chapter,  the 
external  membrane  of  the  egg  becomes  vascular  by  the  formation 
of  the  allantoic  bloodvessels,  which  emerge  from  the  body  of  the 
foetus,  to  ramify  in  the  chorion,  and  penetrate  everywhere  into  the 
villosities  with  which  it  is  covered.  Each  villosity,  then,  as  it  lies 
imbedded  in  its  uterine  follicle,  contains  a  vascular  loop  through 
which  the  foetal  blood  circulates,  increasing  the  rapidity  with  which 
absorption  and  exhalation  take  place. 

Subsequently,  furthermore,  these  vascular  tufts,  which  are  at  first 
uniformly  abundant  throughout  the  whole  extent  of  the  chorion, 
disappear  over  a  portion  of  its  surface,  while  they  at  the  same  time 


Imprrgnatf,  I)  Uterus; 
showiug  coiiuection  between  vil- 
losities of  chorion  and  decidual 
membranes. 


522        DEVELOPMENT    OF    UTERINE    MUCOUS    MEMBRANE. 


Fig.  206. 


become  concentrated  and  still  further  developed  at  a  particular 
spot,  the  situation  of  the  future  placenta.  (Fig.  206.)     This  is  the 

spot  at  which  the  egg  is  in  contact  with 
the  decidua  vera.   Here,  therefore,  both 
the  decidual  membrane  and  the  tufts 
of  the  chorion  continue  to  increase  in 
thickness  and  vascularity;  while  else- 
where, over  the  prominent  portion  of 
the  egg,  the  chorion  not  only  becomes 
bare  of  villosities,  and  comparatively 
destitute  of  vessels,  but  the  decidua  re- 
flexa,  which  is  in  contact  with  it,  also 
loses  its  activity  of  growth,   and  be- 
comes expanded  into  a  thin  layer  nearly 
destitute  of  vessels,  and  without  any 
remaining  trace  of  tubules  or  follicles. 
The   uterine  mucous   membrane   is 
therefore  developed,  during  the  process 
of  gestation,  in  such  a  way  as  to  provide 
for  the  nourishment  of  the  foetus  in  the  different  stages  of  its  growth. 
At  first,  the  whole  of  it  is  uniformly  increased  in  thickness  (decidua 
vera).     Next,  a  portion  of  it  grows  upward  around  the  egg,  and 
"  covers  its  projecting  surface  (decidua  reflexa).     Afterward,  both  the 
decidua  reflexa  and  the  greater  part  of  the  decidua  vera  diminish 
in  the  activity  of  their  growth,  and  lose  their  importance  as  a  means 
,   of  nourishment  for  the  egg;  while  that  part  which  is  in  contact  with 
the  vascular  tufts  of  the  chorion  continues  to  grow,  becoming  ex- 
ceedingly developed,  and  taking  an  active  part  in  the  formation  of 
the  placenta. 

In  the  following  chapter,  we  shall  examine  more  particularly  the 
structure  and  development  of  the  placenta  itself,  and  of  those  parts 
which  are  immediately  connected  with  it. 


Pre.jnaxt  Utercs;  showing 
formation  of  placenta,  by  the  united 
development  of  a  portion  of  the  de- 
cidna   and   the  villosities  of  the  cho- 


THE    PLACENTA.  523 


CHAPTER   XII. 

THE    PLACENTA. 

We  have  shown  in  the  preceding  chapters  that  the  foetus,  during 
its  development,  depends  for  its  supply  of  nutriment  upon  the  lining 
membrane  of  the  maternal  uterus;  and  that  the  nutriment,  so  sup- 
plied, is  absorbed  by  the  bloodvessels  of  the  chorion,  and  transported 
in  this  way  into  the  circulation  of  the  foetus.  In  all  instances,  ac- 
cordingly, in  which  the  development  of  the  foetus  takes  place  within 
the  body  of  the  parent,  it  is  provided  for  by  the  relation  thus  esta- 
blished between  two  sets  of  membranes;  namely,  the  maternal 
membranes  which  supply  nourishment,  and  the  foetal  membranes 
which  absorb  it. 

In  some  species  of  animals,  the  connection  between  the  maternal 
and  foetal  membranes  is  exceedingly  simple.     In  the  pig,  for  ex- 
ample,  the  uterine   mucous  membrane  is  everywhere  uniformly 
vascular;  its  only  peculiarity  consisting  in  the  presence  of  nume- 
rous transverse  folds,  which  project  from  its  surface,  analogous  to 
the  valvulse  conniventes  of  the  small  intestine.     The  external  in- 
vesting membrane  of  the  egg,  which  is  the  allantois,  is  also  smooth 
and  uniformly  vascular  like  the  other.     No  special  development  of 
tissue  or  of  vessels  occurs  at  any  part  of  these  membranes,  and 
no  direct  adhesion  takes  place  between  them ;  but  the  vascular 
allantois  or  chorion  of  the  foetus  is  everywhere  closely  applied  to 
the  vascular  mucous  membrane  of  the  maternal  uterus,  each  of  the 
two  contiguous  surfaces  following  the  undulations  presented  by  the 
other.  (Fig.  207.)     By  this  arrangement,  transudation  and  absorp- 
tion take  place  from  the  bloodvessels  of  the  mother  to  those  of  the 
foetus,  in  sufficient  quantity  to  provide  for  the  nutrition  of  the  latter. 
When  parturition  takes  place,  accordingly,  in  these  animals,  a  very 
moderate  contraction  of  the  uterus  is  sufficient  to  expel  its  contents. 
The  egg,  displaced  from  its  original  position,  slides  easily  forward 
over  the  surface  of  the  uterine  mucous  membrane,  and  is  at  last 
discharged  without   any  hemorrhage  or  laceration  of  connecting 


524 


THE    PLACENTA. 


parts.     In  other  instances,  however,  the  development  of  the  foetus 
requires  a  more  elaborate  arrangement  of  the  vascular  membranes. 


Fi!?.  207. 


FcETAL   I'ifi,    with  its  membranes,  contaiiir-d  in   cavity  of  uterus.- 
c,  c.  Cavity  uf  uterus,     d.   Amnion,     e,  e.   Allantoi.s. 


I,  a,  6,  6.  Walls  of  uterus. 


In  the  cow,  for  example,  the  external  membrane  of  the  Q^g^  beside 
being  everywhere  supplied  with  branching  vessels,  presents  upon 
various  points  of  its  surface  no  less  than  from  seventy  to  eighty  oval 
spots,  at  each  of  which  the  vessels  of  the  chorion  are  developed  into 
abundant  tufted  prominences,  hanging  from  its  exterior  as  a  thick, 
velvety,  vascular  mass.  At  each  point  of  the  uterine  mucous  mem- 
brane, corresponding  with  one  of  these  tufted  masses,  the  maternal 
bloodvessels  are  developed  in  a  similar  manner,  projecting  into  the 
uterine  cavity  as  a  flattened  rounded  mass  or  cake;  which,  with  that 
part  of  the  foetal  chorion  which  is  adherent  to  it,  is  known  by  the 


Cotyledon  op  Cow's  Uterus.— a,  a.  Surface  of  fretai  chorion  6,  6.  Bloodve'ssels  of  fcetal 
chorion,  d,  d.  Bloodvessels  of  uterine  mucous  membrane,  c,  c.  Surface  of  uterine  mucous  mem- 
braue. 

name  of  the   Cotyledon.     Each  cotyledon  forms,  therefore,  a  little 
placenta.  (Fig.  208.)     In   its  substance  the  tufted  vascular   loops 


THE    PLACENTA.  525 

coming  from  the  uterine  mucous  membrane  {d,  d)  are  entangled 
with  those  coming  from  the  membranes  of  the  foetus  {b,  b).  There 
is  no  absolute  adhesion  between  the  two  sets  of  vessels,  but  only 
an  interlacement  of  their  ramified  extremities;  and  with  a  little 
care  in  manipulation  the  foetal  portion  of  the  cotyledon  may  be 
extricated  from  the  maternal  portion,  without  lacerating  either.  In 
consequence,  however,  of  this  intricate  interlacement  of  the  vessels, 
transudation  of  fluids  will  evidently  take  place  with  great  readiness, 
from  one  system  to  the  other. 

The  form  of  placenta,  therefore,  met  with  in  these  animals,  is  one 
in  which  the  bloodvessels  of  the  foetal  chorion  are  simply  entangled 
with  those  of  the  uterine  mucous  membrane.  In  the  human  sub- 
ject, the  structure  of  the  placenta  is  a  little  more  complicated,  though 
the  main  principles  of  its  formation  are  the  same  as  in  the  above 
instances. 

From  what  has  already  been  said  in  the  foregoing  chapters,  it 
appears  that  in  the  human  subject,  as  well  as  in  the  lower  animals, 
the  placenta  is  formed  partly  by  the  vascular  tufts  of  the  chorion, 
and  partly  by  the  thickened  mucous  membrane  of  the  uterus  in 
which  they  are  entangled.  During  the  third  month,  those  portions 
of  the  chorion  and  decidua  which  are  destined  to  undergo  this 
transformation  become  more  or  less  distinctly  limited  in  their  form 
and  dimensions ;  and  a  thickened  vascular  mass,  partly  maternal 
and  partly  foetal  in  its  origin,  shows  itself  at  the  spot  where  the 
placenta  is  afterward  to  be  developed.  This  mass  is  constituted  in 
the  following  manner. 

It  will  be  recollected  that  the  villi  of  the  chorion,  when  first 
formed,  penetrate  into  follicles  situated  in  the  substance  of  the 
uterine  mucous  membrane;  and  that  after  they  have  become  vas- 
cular, they  elongate  rapidly  and  are  developed  into  tufted  ramifi- 
cations of  bloodvessels,  each  one  of  which  turns  upon  itself  in  a 
loop  at  the  end  of  the  villus.  At  the  same  time  the  uterine  follicle, 
into  which  the  villus  has  penetrated,  enlarges  to  a  similar  extent ; 
sending  out  branching  diverticula,  corresponding  with  the  mutiplied 
ramifications  of  the  villus.  In  fact,  the  growth  of  the  follicle  and 
that  of  the  villus  go  on  simultaneously  and  keep  pace  with  each 
other ;  the  latter  constantly  advancing  as  the  cavity  of  the  former 
enlarges. 

But  it  is  not  only  the  uterine  follicles  which  increase  in  size  and 
in  complication  of  structure  at  this  period.  The  capillary  blood- 
vessels, which  lie  between  them  and  ramify  over  their  exterior, 


52Q  THE    PLACENTA. 

also  become  unusually  developed.  They  enlarge  and  inosculate 
freely  with  each  other;  so  that  every  uterine  follicle  is  soon  covered 
with  an  abundant  network  of  dilated  capillaries,  derived  from  the 
bloodvessels  of  the  original  decidua.  At  this  time,  therefore,  each 
vascular  loop  of  the  foetal  chorion  is  covered,  first,  with  a  layer 
forming  the  wall  of  the  villus.  This  is  in  contact  with  the  lining 
membrane  of  a  uterine  follicle,  and  outside  of  this  again  are  the 
capillary  vessels  of  the  uterine  mucous  membrane ;  so  that  two 
distinct  membranes  intervene  between  the  walls  of  the  foetal  capil- 
laries on  the  one  hand  and  those  of  the  maternal  capillaries  on  the 
other,  and  all  transudation  must  take  place  through  the  substance 
of  these  two  membranes. 

As  the  formation  of  the  placenta  goes  on,  the  anatomical  arrange- 
ment of  the  foetal  vessels  remains  the  same.  They  continue  to 
form  vascular  loops,  penetrating  deeply  into  the  decidual  mem- 
brane; only  they  become  constantly  more  elongated,  and  their 
ramifications  more  abundant  and  tortuous.  The  maternal  capilla- 
ries, however,  situated  on  the  outside  of  the  uterine  follicles,  become 
considerably  altered  in  their  anatomical  relations.  They  enlarge 
excessively;  and,  by  encroaching  constantly  upon  the  little  islets 
or  spaces  between  them,  fuse  successively  with  each  other;  and, 
losing  gradually  in  this  way  the  characters  of  a  capillary  network, 
become  dilated  into  wide  sinuses,  which  communicate  freely  with 
the  enlarged  vessels  in  the  muscular  walls  of  the  uterus.  As  the 
original  capillary  plexus  occupied  the  entire  thickness  of  the  hyper- 
trophied  decidua,  the  vascular  sinuses,  into  which  it  is  thus  con- 
verted, are  equally  extensive.  They  commence  at  the  inferior 
surface  of  the  placenta,  where  it  is  in  contact  with  the  muscular 
walls  of  the  uterus,  and  extend  through  its  whole  thickness,  quite 
up  to  the  surface  of  the  foetal  chorion. 

As  the  maternal  sinuses  grow  upward,  the  vascular  tufts  of  the 
chorion  grow  downward,  and  extend  also  through  the  entire  thick- 
ness of  the  placenta.  At  this  period,  the  development  of  the 
bloodvessels,  both  in  the  foetal  and  maternal  portions  of  the  placenta, 
is  so  excessive  that  all  the  other  tissues,  which  originally  co-ex- 
isted with  them,  become  retrograde  and  disappear  almost  altogether. 
If  a  villus  from  the  foetal  portion  of  the  placenta  be  examined  at  this 
time  by  transparency,  in  the  fresh  condition,  it  will  be  seen  that  its 
bloodvessels  are  covered  only  with  a  layer  of  homogeneous,  or  finely 
granular  material,  -ggV^  of  an  inch  in  thickness,  in  which  are  im- 
bedded small  oval-shaped  nuclei,  similar  to  those  seen  at  an  earlier 


THE    PLACENTA. 


527 


Fig.  209. 


period  in  the  villosities  of  the  chorion.  The  villosities  of  the  cho- 
rion are  now,  therefore,  hardly  anything  more  than  ramified  and  tor- 
tuous vascular  loops;  the  remaining  sub- 
stance of  the  villi  having  been  atrophied 
and  absorbed  in  the  excessive  growth  of 
the  bloodvessels.  (Fig.  209.)  The  uterine 
follicles  have  at  the  same  time  lost  all  trace 
of  their  original  structure,  and  have  be- 
come mere  vascular  sinuses,  into  which 
the  tufted  foetal  bloodvessels  are  received, 
as  the  villosities  of  the  chorion  were  at 
first  received  into  the  uterine  follicles. 

Finally,  the  walls  of  the  foetal  blood- 
vessels having  come  into  close  contact 
with  the  walls  of  the  maternal  sinuses, 
the  two  become  adherent  and  fuse  toge- 
ther ;  so  that  a  time  at  last  arrives,  when 
we  can  no  longer  separate  the  foetal  ves- 
sels, in  the  substance  of  the  placenta,  from  the  maternal  sinuses 
without  lacerating  either  the  one  or  the  other,  owing  to  the  second- 
ary adhesion  which  has  taken  place  between  them. 

The  placenta,  therefore,  when  perfectly  formed,  has  the  structure 
which  is  shown  in  the  accompanying  diagram  (Fig.  2i0),  repre- 


Extreraity  of  Foetal  Tuft 
of  humaa  placenta;  from  an  in- 
jected specimen.  Magnified  40 
diameters. 


Fiff.  210. 


Vertical  section  of  Placenta,  showing  arrangement  of  maternal  and  fcetal  vess 
rion.     6,  6.  Decidua.     c,  c,  c,  c.  Orifices  of  uterine  sinuses. 


528  THE  PLACENTA. 

senting  a  vertical  section  of  the  organ  through  its  entire  thickness. 
At  a,  a,  is  seen  the  chorion,  receiving  the  umbilical  vessels  from  the 
body  of  the  foetus  through  the  umbilical  cord,  and  sending  out  its 
compound  and  ramified  vascular  tufts  into  the  substance  of  the  pla- 
centa. At  b  b,  is  the  attached  surface  of  the  decidua,  or  uterine 
mucous  membrane ;  and  at  c,  c,  c,  c,  are  the  orifices  of  uterine  ves- 
sels which  penetrate  it  from  below.  These  vessels  enter  the  placenta 
in  an  extremely  oblique  direction,  though  they  are  represented  in 
the  diagram,  for  the  sake  of  distinctness,  as  nearly  perpendicular. 
When  they  have  once  penetrated,  however,  the  lower  portion  of 
the  decidua,  they  immediately  dilate  into  the  placental  sinuses 
(represented,  in  the  diagram,  in  black),  which  extend  through  the 
whole  thickness  of  the  organ,  closely  embracing  all  the  ramifica- 
tions of  the  foetal  tufts.  It  will  be  seen,  therefore,  that  the  placenta, 
arrived  at  this  stage  of  completion,  is  composed  essentially  of 
nothing  but  bloodvessels.  No  other  tissues  enter  into  its  structure, 
for  all  those  which  it  originally  contained  have  disappeared,  ex- 
cepting the  bloodvessels  of  the  foetus,  entangled  with  and  adherent 
to  the  bloodvessels  of  the  mother. 

There  is,  however,  no  direct  communication  between  the  foetal 
and  maternal  vessels.  The  blood  of  the  foetus  is  always  separated 
from  the  blood  of  the  mother  by  a  membrane  which  has  resulted 
from  the  successive  union  and  fusion  of  four  different  membranes, 
viz,,  first,  the  membrane  of  the  foetal  villus ;  secondly,  that  of  the 
uterine  follicle;  thirdly,  the  wall  of  the  foetal  bloodvessel;  and, 
fourthly,  the  wall  of  the  uterine  sinus.  The  single  membrane,  how- 
ever, into  which  these  four  finally  coalesce,  is  extremely  thin,  as 
we  have  seen,  and  of  enormous  extent,  owing  to  the  extremely 
abundant  branching  and  subdivision  of  the  foetal  tufts.  These  tufts, 
accordingly,  in  which  the  blood  of  the  foetus  circulates,  are  bathed 
everywhere,  in  the  placental  sinuses,  with  the  blood  of  the  mo- 
ther ;  and  the  processes  of  endosmosis  and  exosmosis,  of  exhala- 
tion and  absorption,  go  on  between  the  two  with  the  greatest  pos- 
sible activity. 

It  is  very  easy  to  demonstrate  the  arrangement  of  the  foetal 
tufts  in  the  human  placenta.  They  can  be  readily  seen  by  the 
naked  eye,  and  may  be  easily  traced  from  their  attachment  at  the 
under  surface  of  the  chorion  to  their  termination  near  the  uterine 
surface  of  the  placenta.  The  anatomical  disposition  of  the  pla- 
cental sinuses,  however,  is  much  more  difficult  of  examination. 
During  life,  and  while  the  placenta  is  still  attached  to  the  uterus, 


THE    PLACENTA.  529 

they  are  filled,  of  course,  with  the  blood  of  the  mother  and  occupy 
fully  one-half  the  entire  mass  of  the  placenta.  But  when  the  pla- 
centa is  detached,  the  maternal  vessels  belonging  to  it  are  torn  off' 
at  their  necks  (Fig.  210,  c,  c,  c,  c),  and  the  sinuses,  being  then 
emptied  of  blood  by  the  compression  to  which  the  placenta  is  sub- 
jected, are  apparently  obliterated ;  and  the  foetal  tufts,  falling  to- 
gether and  lying  in  contact  with  each  other,  appear  to  constitute 
the  whole  of  the  placental  mass.  The  existence  of  the  placental 
sinuses,  however,  and  their  true  extent,  may  be  satisfactorily  de- 
monstrated in  the  following  manner. 

If  we  take  the  uterus  of  a  woman  who  has  died  undelivered  at 
the  full  term  or  thereabout,  and  open  it  in  such  a  way  as  to  avoid 
wounding  the  placenta,  this  organ  will  be  seen  remaining  attached 
to  the  uterine  surface,  with  all  its  vascular  connections  complete. 
Let  the  foetus  now  be  removed  by  dividing  the  umbilical  cord,  and 
the  uterus,  with  the  placenta  attached,  placed  under  water,  with  its 
internal  surface  uppermost.  If  the  end  of  a  blowpipe  be  now 
introduced  into  one  of  the  divided  vessels  of  the  uterine  walls, 
and  air  forced  in  by  gentle  insufflation,  we  can  easily  inflate,  first, 
the  venous  sinuses  of  the  uterus  itself,  and  next,  the  deeper  por- 
tions of  the  placenta;  and  lastly,  the  bubbles  of  air  insinuate  them- 
selves everywhere  between  the  foetal  tufts,  and  appear  in  the  most 
superficial  portions  of  the  placenta,  immediately  underneath  the 
transparent  chorion  (a  a,  Fig.  210);  thus  showing  that  the  placental 
sinuses,  which  freely  communicate  with  the  uterine  vessels,  really 
occupy  the  entire  thickness  of  the  placenta,  and  are  equally  ex- 
tensive with  the  tufts  of  the  chorion.  We  have  verified  this  fact 
in  the  above  manner,  on  four  different  occasions,  and  in  the  pre- 
sence of  Prof.  C.  E.  Gilman,  Dr.  Geo.  T.  Elliot,  Dr.  Henry  B.  Sands, 
Dr.  T.  G.  Thomas,  Dr.  T.  C.  Finnell,  and  various  other  medical 
gentlemen  of  New  York. 

If  the  placenta  be  now  detached  and  examined  separately,  it  will 
be  found  to  present  upon  its  uterine  surface  a  number  of  openings 
which  are  extremely  oblique  in  their  position,  and  which  are 
accordingly  bounded  on  one  side  by  a  very  thin,  projecting,  cres- 
centic  edge.  These  are  the  orifices  of  the  uterine  vessels,  passing 
into  the  placenta  and  torn  off"  at  their  necks,  as  above  described ; 
and  by  carefully  following  them  with  the  probe  and  scissors,  they 
are  found  to  lead  at  once  into  extensive  empty  cavities  (the  pla 
cental  sinuses),  situated  between  the  foetal  tufts.  We  have  already 
shown  that  these  cavities  are  filled  during  life  with  the  maternal 
34 


530  THE    PLACENTA. 

blood ;  and  there  is  every  reason  to  believe  that  before  delivery, 
and  while  the  circulation  is  going  on,  the  placenta  is  at  least  twice 
as  large  as  after  it  has  been  detached  and  expelled  from  the  uterus. 

The  placenta,  accordingly,  is  a  double  organ,  formed  partly  by 
the  chorion  and  partly  by  the  decidua ;  and  consisting  of  maternal 
and  foetal  bloodvessels,  inextricably  entangled  and  united  with  each 
other. 

The  part  which  this  organ  takes  in  the  development  of  the  foetus 
is  an  exceedingly  important  one.  From  the  date  of  its  formation, 
at  about  the  beginning  of  the  fourth  month,  it  constitutes  the  only 
channel  through  which  nourishment  is  conveyed  from  the  mother 
to  the  foetus.  The  nutritious  materials,  which  circulate  in  abun- 
dance in  the  blood  of  the  maternal  sinuses,  pass  through  the  inter- 
vening membrane  by  endosmosis,  and  enter  the  blood  of  the  foetus. 
The  healthy  or  injurious  regimen,  to  which  the  mother  is  subjected, 
will  accordingly  exert  an  almost  immediate  influence  upon  the 
child.  Even  medicinal  substances,  taken  by  the  mother  and  ab- 
sorbed into  her  circulation,  may  readily  transude  through  the  pla- 
cental vessels ;  and  they  have  been  known  in  this  way  to  exert  a 
Sj^ecific  effect  upon  the  foetal  organization. 

The  placenta  is,  furthermore,  an  organ  of  exhalation  as  well  as 
of  absorption.  The  excrementitious  substances,  produced  in  the 
circulation  of  the  foetus,  are  undoubtedly  in  great  measure  disposed 
of  by  transudation  through  the  walls  of  the  placental  vessels,  to  be 
afterward  discharged  by  the  excretory  organs  of  the  mother.  The 
system  of  the  mother  may  therefore  be  affected  in  this  manner  by 
influences  derived  from  the  foetus.  It  has  been  remarked  more 
than  once,  in  the  lower  animals,  that  when  the  female  has  two  suc- 
cessive litters  of  young  by  different  males,  the  young  of  the  second 
litter  will  sometimes  bear  marks  resembling  those  of  the  first  male. 
In  these  instances,  the  peculiar  influence  which  produces  the  ex- 
ternal mark  must  have  been  transmitted  by  the  first  male  directly 
to  the  foetus,  from  the  foetus  to  the  mother,  and  from  the  mother  to 
the  foetus  of  the  second  litter. 

It  is  also  through  the  placental  circulation  that  those  disturbing 
effects  are  produced  upon  the  nutrition  of  the  foetus,  which  result 
from  sudden  shocks  or  injuries  inflicted  upon  the  mother.  There  is 
now  little  room  for  doubt  that  various  deformities  and  deficiencies  of 
the  foetus,  conformably  to  the  popular  belief,  do  really  originate,  in 
certain  cases,  from  nervous  impressions,  such  a^  disgust,  fear  or  anger, 
experienced  by  the  mother.     The  mode  in  which  these  effects  may 


TFIE    PLACENTA.  531 

be  produced  is  readily  understood  from  what  has  been  said  above  of 
the  anatomy  and  functions  of  the  placenta.  We  know  very  well 
how  easily  nervous  impressions  will  disturb  the  circulation  in  the 
brain,  the  face,  the  lungs,  &;c, ;  and  the  uterine  circulation  is  quite 
as  readily  influenced  by  similar  causes,  as  physicians  see  everyday 
in  cases  of  amenorrhoea,  menorrhagia,  &c.  If  a  nervous  shock  may 
excite  premature  contraction  in  the  muscular  fibres  of  the  pregnant 
uterus  and  produce  abortion,  as  not  unfrequently  happens,  it  is  cer- 
tainly capable  of  disturbing  the  course  of  the  circulation  through 
the  same  organ.  But  the  foetal  circulation  is  dependent,  to  a  great 
extent,  on  the  maternal.  Since  the  two  sets  of  vessels  are  so  closely 
entwined  in  the  placenta,  and  since  the  foetal  blood  has  here  much 
the  same  relation  to  the  maternal,  that  the  blood  in  the  pulmonary 
capillaries  has  to  the  air  in  the  air-vesicles,  it  will  be  liable  to  de 
rangement  from  similar  causes.  If  the  circulation  of  air  through 
the  pulmonary  tubes  and  vesicles  be  suspended,  that  of  the  blood 
through  the  capillaries  comes  to  an  end  also.  In  the  same  way, 
whatever  disturbs  or  arrests  the  circulation  through  the  vessels  of 
the  maternal  uterus  must  necessarily  be  liable  to  interfere  with  that 
in  the  foetal  capillaries  forming  part  of  the  placenta.  And  lastly,  as 
the  nutrition  of  the  foetus  is  provided  for  wholly  by  the  placenta,  it 
will  of  course  suffer  immediately  from  any  such  disturbance  of  the 
placental  circulation.  These  effects  may  be  manifested  either  in  the 
general  atrophy  and  death  of  the  foetus  ;  or,  if  the  disturbing  cause 
be  slight,  in  the  atrophy  or  imperfect  development  of  particular 
parts;  just  as,  in  the  adult,  a  morbid  cause  operating  through  the 
entire  system,  may  be  first  or  even  exclusively  manifested  in  some 
particular  organ,  which  is  more  sensitive  to  its  influence  than  other 
parts. 

The  placenta  must  accordingly  be  regarded  as  an  organ  which 
performs,  during  intra-uterine  life,  offices  similar  to  those  of  the 
lungs  and  the  intestine  after  birth.  It  absorbs  nourishment,  reno- 
vates the  blood,  and  discharges  by  exhalation  various  excrementi- 
tious  matters,  which  originate  in  the  processes  of  foetal  nutrition. 


532 


DISCHARGE    OF    THE    OVUM. 


CHAPTER    XIII. 


DISCHAKGE     OF     THE     OVUM,    AND     RETROGRADE 
DEVELOPMENT    (INVOLUTION)    OF    THE    UTERUS. 

During  the  growth  of  the  ovum  and  the  formation  of  the  pla- 
cental structures,  the  muscular  substance  of  the  uterus  also  in- 
creases in  thickness,  while  the  whole  organ  enlarges,  in  order  to 
accommodate  the  growing  foetus  and  its  appendages.  The  relative 
positions  of  the  amnion  and  chorion,  furthermore,  undergo  a  change 
during  the  latter  periods  of  gestation,  and  the  umbilical  cord  be- 
comes developed,  at  the  same  time,  in  the  following  manner. 

In  the  earlier  periods  of  foetal  life  the  umbilical  cord  consists 
simply  of  that  portion  of  the  allantois  lying  next  the  abdomen.  It 
is  then  very  short,  and  contains  the  umbilical  vessels  running  in  a 
nearly  straight  course,  and  parallel  with  each  other,  from  the  abdo- 
men of  the  foetus  to  the  external  portions  of  the  chorion.  At  this 
time   the   amnion  closely  invests  the  body  of  the  foetus,  so  that 

the  size  of  its  cavity  is  but  little 
Fis-  211.  larger  than  that  of  the  foetus.  (Fig. 

211.)  The  space  between  the 
amnion  and  the  chorion  is  then 
occupied  by  an  amorphous  gela- 
tinous material,  in  which  lies  im- 
bedded the  umbilical  vesicle. 

Afterward,  however,  the  am- 
nion enlarges  faster  than  the  cho- 
rion, and  encroaches  upon  the 
layer  of  gelatinous  matter  situated 
between  the  two  (Fig.  212),  at 
the  same  time  that  an  albuminous 
fluid,  the  "amniotic  fluid,"  is  ex- 
uded into  its  cavity,  in  constantly 
increasing  quantity.  Subsequently,  the  gelatinous  layer,  above  de- 
scribed, altogether  disappears,  and  the  amnion,  at  about  the  begin- 


HcMAX  Ovum  about  the  end  of  the  first 
month. — 1.  Umbilical  vesicle.  2.  Amnion.  3. 
Choiiuu. 


ENLARGEMENT    OF    THE    AMNION, 


533 


Human  Ovum  at  end  of  third  month;  showing 
enlargement  of  amnion. 


ning  of  the  fifth  month,  comes  in  contact  with  the  internal  surface 

of  the  chorion.     Finally,  toward  the  end  of  gestation,  the  contact 

becomes  so  close  between  these 

two  membranes  that  they  are  ^'?-  ■^^^• 

partially    adherent     to     each 

other,  and  it  requires  a  little 

care  to  separate  them  without 

laceration. 

The  quantity  of  the  amniotic 
fluid  continues  to  increase  dur- 
ing the  latter  periods  of  gesta- 
tion in  order  to  accommodate 
the  movements  of  the  foetus. 
These  movements  begin  to  be 
perceptible  about  the  fifth 
month,  at  which  time  the 
muscular  system  has  already 
attained  a  considerable  degree  of  development,  but  become  after- 
ward more  frequent  and  more  strongly  pronounced.  The  space 
and  freedom  requisite  for  these  movements  are  provided  for  by  the 
fluid  accumulated  in  the  cavity  of  the  amnion. 

The  umbilical  cord  elongates,  at  the  same  time,  in  proportion  to 
the  increasing  size  of  the  amniotic  cavity.  During  its  growth,  it 
becomes  spirally  twisted  from  right  to  left,  the  two  umbilical  arte- 
ries winding  round  the  vein  in  the  same  direction.  The  gelatinous 
matter,  already  described  as  existing  between  the  amnion  and 
chorion,  while  it  disappears  elsewhere,  accumulates  in  the  cord  in 
considerable  quantity,  covering  the  vessels  with  a  thick,  elastic  en- 
velope, which  protects  them  from  injury  and  prevents  their  being 
accidentally  compressed  or  obliterated.  The  whole  is  covered  by  a 
portion  of  the  amnion,  which  is  connected  at  one  extremity  with  the 
integument  of  the  abdomen,  and  invests  the  whole  of  the  cord  with 
a  continuous  sheath,  like  the  finger  of  a  glove.  (Fig.  213,) 

The  cord  also  contains,  for  a  certain  period,  the  pedicle  or  stem 
of  the  umbilical  vesicle.  The  situation  of  this  vesicle,  it  will  be 
recollected,  is  always  between  the  chorion  and  the  amnion.  Its 
pedicle  gradually  elongates  with  the  growth  of  the  umbilical  cord; 
and  the  vesicle  itself,  which  generally  disappears  soon  after  the 
third  month,  sometimes  remains  as  late  as  the  fifth,  sixth,  or  seventh. 
According  to  Prof.  Mayer,  of  Bonn,  it  may  even  be  found,  by  care- 
ful search,  at  the  termination  of  pregnancy.     When  discovered  in 


584  DISCHARGE    OF    THE    OVUM. 

the  middle  and  latter  periods  of  gestation,  it  presents  itself  as  a 
small,  flattened,  and  shrivelled  vesicle,  situated  underneath  the 
amnion,  at  a  variable  distance  from  the  insertion  of  the  umbilical 
cord.  A  minute  bloodvessel  is  often  seen  running  to  it  from  the 
cord,  and  ramifying  upon  its  surface. 

Fig.  213. 


Gravid  Human  Utekus  and  Contents,  showing  the  relations  of  the  cord,  placenta,  mem- 
branes, &c.,  about  the  end  of  the  seventh  month. — 1.  Decidua  vera.  2.  Decidua  reflexa.  .S.  Chorion. 
4.  Amnion. 

The  decidua  reflexa,  during  the  liitter  months  of  pregnancy,  is 
constantly  distended  and  pushed  back  by  the  increasing  size  of  the 
egg;  so  that  it  is  finally  pressed  closely  against  the  opposite  surface 
of  the  decidua  vera,  which  still  lines  the  greater  part  of  the  uterine 
cavity.  By  the  end  of  the  seventh  month,  the  opposite  surfaces 
of  the  decidua  vera  and  reflexa  are  in  complete  contact  with  each 
other,  though  still  distinct  and  capable  of  being  separated  without 
difficulty.  After  that  time,  they  fuse  together  and  become  con- 
founded with  each  other ;  the  two  at  last  forming  only  a  single, 
thin,  friable,  semi-opaque  layer,  in  which  no  trace  of  their  original 
oflandular  structure  can  be  discovered. 

This  is  the  condition  of  things  at  the  termination  of  pregnancy. 
Then,  the  time  having  arrived  for  parturition  to  take  place,  the 
hypertrophied  muscular  walls  of  the  uterus  contract  forcibly  upon 
its  contents,  and  the  egg  is  discharged,  together  with  the  whole  of 
the  decidual  uterine  mucous  membrane. 

In  the  human  subject,  as  well  as  in  most  quadrupeds,  the  mem- 


SEPARATION  OF  THE  PLACENTA.  635 

branes  of  the  egg  are  usually  ruptured  during  the  process  of  par- 
turition; and  the  foetus  escapes  first,  the  placenta  and  the  rest  of 
the  appendages  following  a  few  moments  afterward.  Occasionally, 
however,  even  in  the  human  subject,  the  egg  is  discharged  entire, 
and  the  foetus  liberated  afterward  by  the  laceration  of  the  mem- 
branes. In  each  case,  however,  the  mode  of  separation  and  expul- 
sion is,  in  all  important  particulars,  the  same. 

The  process  of  parturition,  therefore,  consists  essentially  in  a 
separation  of  the  decidual  membrane,  which,  on  being  discharged, 
brings  away  the  ovum  with  it.  The  greater  part  of  the  decidua 
vera,  having  fallen  into  a  state  of  atrophy  during  the  latter  months 
of  pregnancy,  is  by  this  time  nearly  destitute  of  vessels,  and  sepa- 
rates, accordingly,  without  any  perceptible  hemorrhage.  That  por- 
tion, however,  which  enters  into  the  formation  of  the  placenta,  is, 
on  the  contrary,  excessively  vascular;  and  when  the  placenta  is 
separated,  and  its  maternal  vessels  torn  off  at  their  necks,  as  before 
mentioned,  a  gush  of  blood  takes  place,  which  accompanies  or 
immediately  follows  the  birth  of  the  foetus.  This  hemorrhage, 
which  occurs  as  a  natural  phenomenon  at  the  time  of  parturition, 
does  not  come  from  the  uterine  vessels  proper.  It  consists  of  the 
blood  which  was  contained  in  the  placental  sinuses,  and  which  is 
expelled  from  them  owing  to  the  compression  of  the  placenta  by 
the  walls  of  the  uterus.  Since  the  whole  amount  of  blood  thus 
lost  was  previously  employed  in  the  placental  circulation,  and  since 
the  placenta  itself  is  thrown  off  at  the  same  time,  no  unpleasant 
effect  is  produced  upon  the  mother  by  such  a  hemorrhage,  because 
the  natural  proportion  of  blood  in  the  rest  of  the  maternal  system 
remains  the  same.  Uterine  hemorrhage  at  the  time  of  parturition, 
therefore,  becomes  injurious  only  when  it  continues  after  complete 
separation  of  the  placenta ;  in  which  case  it  is  supplied  by  the 
mouths  of  the  uterine  vessels  themselves,  left  open  by  failure  of  the 
uterine  contractions.  These  vessels  are  usually  instantly  closed, 
after  separation  of  the  placenta,  by  the  contraction  of  the  muscular 
fibres  of  the  uterus.  They  pass,  as  we  have  already  mentioned,  in 
a,n  exceedingly  oblique  direction,  from  the  uterine  surface  to  the 
placenta ;  and  the  muscular  fibres,  which  cross  them  transversely 
above  and  below,  necessarily  constrict  them,  and  effectually  close 
their  orifices,  immediately  on  being  thrown  into  a  state  of  contraction. 

Another  very  remarkable  phenomenon,  connected  with  preg- 
nancy and  parturition,  is  the  appearance  in  the  uterus  of  a  new 
mucous  membrane,  growing  underneath  the  old,  and  ready  to 
take  the  place  of  the  latter  after  its  discharge. 


536  DISCHARGE    OF    THE    OVUM. 

If  the  internal  surface  of  the  body  of  the  uterus  be  examined 
immediately  after  parturition,  it  will  be  seen  that  at  the  spot  where 
the  placenta  was  attached  every  trace  of  mucous  membrane  has 
disappeared.  The  muscular  fibres  of  the  uterus  are  here  perfectly 
exposed  and  bare;  while  the  mouths  of  the  ruptured  uterine  sinuses 
are  also  visible,  with  their  thin,  ragged  edges  hanging  into  the 
cavity  of  the  uterus,  and  their  orifices  plugged  with  more  or  less 
abundant  bloody  coagula. 

Over  the  rest  of  the  uterine  surface  the  decidua  vera  has  also 
disappeared.  Here,  however,  notwithstanding  the  loss  of  the  ori- 
ginal mucous  membrane,  the  muscular  fibres  are  not  perfectly  bare, 
but  are  covered  with  a  thin,  semi-transparent  film,  of  a  whitish  color 
and  soft  consistency.  This  film  is  an  imperfect  mucous  membrane 
of  new  formation,  which  begins  to  be  produced,  underneath  the 
old  decidua  vera,  as  early  as  the  beginning  of  the  eighth  month. 
We  have  seen  this  new  mucous  membrane  very  distinctly  in  the 
uterus  of  a  woman  who  died  undelivered  at  the  above  period. 
The  old  mucous  membrane,  or  decidua  vera,  is  at  this  time  some- 
what opaque,  and  of  a  slightly  yellowish  color,  owing  to  a  partial 
fatty  degeneration  which  it  undergoes  in  the  latter  months  of  preg- 
nancy. It  is  easily  raised  and  separated  from  the  subjacent  parts, 
owing  to  the  atrophy  of  its  vascular  connections;  and  the  new 
mucous  membrane,  situated  beneath  it,  is  readily  distinguished  by 
its  fresh  color,  and  healthy,  transparent  aspect. 

The  mucous  membrane  of  the  cervix  uteri,  which  takes  no  part 
in  the  formation  of  the  decidua,  is  not  thrown  off  in  parturition, 
but  remains  in  its  natural  position ;  and  after  delivery  it  may  be 
seen  to  terminate  at  the  os  internum  by  an  uneven,  lacerated  edge, 
where  it  was  formerly  continuous  with  the  decidua. 

Subsequently,  a  regeneration  of  the  mucous  membrane  takes  place 
over  the  whole  extent  of  the  body  of  the  uterus.  The  mucous 
membrane  of  new  formation,  which  is  already  in  existence  at  the 
time  of  delivery,  becomes  thickened  and  vascular;  and  glandular 
tubules  are  gradually  developed  in  its  substance.  At  the  end  of 
two  months  after  delivery,  according  to  Heschl'  and  Longet,^  it  has 
entirely  regained  the  natural  structure  of  the  uterine  mucous  mem- 
brane. It  unites  at  the  os  internum,  by  a  linear  cicatrix,  with  the 
mucous  membrane  of  the  cervix,  and  the  traces  of  its  laceration  at 

'  Zeitschrift  der  K.  K.  Gesellschaft  der  Aerzte,  in  Wien,  1852. 
*  Traite  de  Physiol ogie.     De  la  Generation,  p.  173. 


RETROGRADE  DEVELOPMENT  OF  THE  UTERUS. 


537 


this  spot  afterward  cease  to  be  visible.  At  the  point,  however, 
where  the  placenta  was  attached,  the  regeneration  of  the  mucoas 
membrane  is  less  rapid;  and  a  cicatrix-like  spot  is  often  visible  at 
this  situation  for  several  months  after  delivery. 

The  only  further  change,  which  remains  to  be  described  in  this 
connection,  is  the  fatty  degeneration  and  reconstruction  of  the 
muscular  substance  of  the  uterus.  This  process,  which  is  some- 
times known  as  the  "  involu- 
tion" of  the  uterus,  takes 
place  in  the  following  man- 
ner. The  muscular  fibres 
of  the  unimpregnated  uterus 
are  pale,  flattened,  spindle- 
shaped  bodies  (Fig.  214)  near- 
ly homogeneous  in  structure 
or  very  faintly  granular,  and 
measuring  from  -^^  to  gi^ 
of  an  inch  in  length,  by 
T(T5oo  to  gtj'oo  of  an  inch  in 
width.  During  gestation 
these  fibres  increase  very 
considerably  in  size.  Their 
texture  becomes  much  more 
distinctly  granular,  and  their 
outlines  more  strongly  mark- 
ed. An  oval  nucleus  also 
shows  itself  in  the  central 
part  of  each  fibre.  The  en- 
tire walls  of  the  uterus,  at 
the  time  of  delivery,  are  com- 
posed of  such  muscular  fibres 
as  these,  arranged  in  circu- 
lar, oblique,  and  longitudinal 
bundles. 

About  the  end  of  the  first 
week  after  delivery,  these 
fibres  begin  to  undergo  a 
fatty  degeneration.  (Fig. 
215.)  Their  granules  be- 
come larger  arid  more  pro- 
minent, and  very  soon  as- 
sume   the     appearance     of 


Muscular  Fibres  op  Unimpregnated 
Uterus;  from  a  woman  aged  40,  dead  of  pbihisis 
pulmonalis. 


Fig.  215. 


Muscular  Fibres  of  Human  Uterus,  ten 
days  after  parturition  ;  from  a  woman  dead  of  puer- 
peral fever. 


538 


BISCHAEGE    OF    THE    OVUM. 


Fig.  216. 


molecules  of  fat,  deposited  in  the  substance  of  the  fibre.  The  fatty- 
deposit,  thus  commenced,  increases  in  abundance,  and  the  mole- 
cules continue  to  enlarge  until  they  become  converted  into  fully 
formed  oil-globules,  which  fill  the  interior  of  the  fibre  more  or  less 

completely,  and  mask,  to  a 
certain  extent,  its  anatomical 
characters.  (Fig.  216.)  The 
universal  fatty  degeneration, 
thus  induced,  gives  to  the 
uterus  a  softer  consistency, 
and  a  pale  yellowish  color 
which  is  characteristic  of  it 
at  this  period.  The  muscu- 
lar fibres  which  have  become 
altered  by  the  fatty  deposit 
are  afterward  gradually  ab- 
sorbed and  disappear;  their 
place  being  subsequently 
taken  by  other  fibres  of  new 

M0SCCLAR  Fibres  of  Human  Uterus,  three      formation,  which  already  bc- 
weeks  after  parturition ;  from  a  woman  dead  of  peri-  .  i  i      • 

tonitis.  gin  to  make  their  appearance 

before  the  old  ones  have  been 
completely  destroyed.  As  this  process  goes  on,  it  results  finally 
in  a  complete  renovation  of  the  muscular  substance  of  the  uterus. 
The  organ  becomes  again  reduced  in  size,  compact  in  tissue,  and 
of  a  pale  ruddy  hue,  as  in  the  ordinary  unimpregnated  condition. 
This  entire  renewal  or  reconstruction  of  the  uterus  is  completed, 
according  to  Heschl,'  about  the  end  of  the  second  month  after 
delivery. 


'  Op.  cit. 


DEVELOPMENT    OF    THE    EMBRYO. 


539 


CHAPTER    XIV. 

DEVELOPMENT  OF  THE  E M B R YO— N E R V 0 U S  SYSTEM, 
ORGANS   OF  SENSE,   SKELETON,   AND   LIMBS. 


Fig.  217. 


The  first  trace  of  a  spinal  cord  in  the  embryo  consists  of  the 
double  longitudinal  fold  or  ridge  of  the  blastodermic  membrane, 
which  shows  itself  at  an  early  period,  as  above  described,  on  each 
side  the  median  furrow.  The  two  laminas  of  which  this  is  com- 
posed, on  the  right  and  left  sides  (Fig.  217,  a,  b),  unite  with  each 
other  in  front,  forming  a  rounded  dilatation  (c), 
the  cephalic  extremity,  and  behind  at  c?,  forming 
a  pointed  or  caudal  extremity.  Near  the  poste- 
rior extremity,  there  is  a  smaller  dilatation, 
which  marks  the  future  situation  of  the  lumbar 
enlargement  of  the  spinal  cord. 

As  the  laminae  above  described  grow  upward 
and  backward,  they  unite  with  each  other  upon 
the  median  line,  so  that  the  whole  is  converted 
into  a  hollow  cylindrical  cord,  terminating  ante- 
riorly by  a  bulbous  enlargement,  and  posteriorly 
by  a  pointed  enlargement;  the  central  cavity 
which  it  contains  running  continuously  through 
it,  from  front  to  rear. 

The  next  change  which  shows  itself  is  a  divi- 
sion of  the  anterior  bulbous  enlargement  into  caudai  extremity 
three  secondary  compartments  or  vesicles  (Fig. 
218),  which  are  partially  separated  from  each  other  by  transverse 
constrictions.  These  vesicles  are  known  as  the  three  cerebral  vesi- 
cles, from  which  all  the  different  parts  of  the  encephalon  are  after- 
ward to  be  developed.  The  first,  or  most  anterior  cerebral  vesicle 
is  destined  to  form  the  hemispheres;  the  second,  or  middle,  the 
tubercula  quadrigemina ;  and  the  third,  or  posterior,  the  medulla 
oblongata.     All  three  vesicles  are  at  this  time  hollow,  and  their 


Formation  of  Cere- 
bro-Spinal  Axis  — 
a,  b.  Spinal  cord.  c.  Ce- 
phalic    extremity.       d. 


540 


DEVELOPMENT    OF    THE    EMBRYO. 


Fig.  218. 


cavities  communicate  freely  with  each  other,  through  the  inter- 
vening constrictions. 

Yerj  soon  the  anterior  and  the  posterior  cerebral  vesicles  suffer 
a  further  division  ;  the  middle  one  remain- 
ing undivided.  The  anterior  vesicle  thus 
separates  into  two  portions,  of  which  the 
first,  or  larger,  constitutes  the  hemispheres, 
while  the  second,  or  smaller,  becomes  the 
optic  thalami.  The  third  vesicle  also  sepa- 
rates into  two  portions,  of  which  the  ante- 
rior becomes  the  cerebellum,  and  the  pos- 
terior the  medulla  oblongata. 

There  are,  therefore,  at  this  time,  five 
cerebral  vesicles,  all  of  whose  cavities  com- 
municate with  each  other  and  with  the 
central  cavity  of  the  spinal  cord.  The 
entire  cerebro-spinal  axis,  at  the  same  time, 
becomes  very  strongly  curved  in  an  ante- 
rior direction,  corresponding  with  the  ante- 
rior curvature  of  the  body  of  the  embryo 
(Fig.  219);  so  that  the  middle  vesicle,  or 
that  of  the  tubercula  quadrigemina,  occu- 
pies a  prominent  angle  at  the  upper  part  of 
the  encephalon,  while  the  hemispheres  and  the  medulla  oblongata 
are  situated  below  it,  anteriorly  and  posteriorly. 

At  first,  it  will  be  observed,  the  relative  size  of  the  various  parts 
of  the  encephalon  is  very  different  from  that  which 
they  afterward  attain  in  the  adult  condition.  The 
hemispheres,  for  example,  are  hardly  larger  than 
the  tubercula  quadrigemina;  and  the  cerebellum 
is  very  much  inferior  in  size  to  the  medulla  oblon- 
gata. Soon  afterward,  the  relative  position  and  size 
FffiTAL  Pig,  fire-  of  the  parts  bcgiu  to  alter.  The  hemispheres  and 
long!  Iho°win''g°  bra^a  tubcrcuk  quadrigcmina  grow  faster  than  the  poste- 
rior portions  of  the  encephalon ;  and  the  cerebellum 
becomes  doubled  backward  over  the  medulla  oblon- 
gata. (Fig.  220.)  Subsequently,  the  hemispheres 
rapidly  enlarge,  growing  upward  and  backward, 
so  as  to  cover  in  and  conceal  both  the  optic  thalami  and  the  tuber- 
cula quadrigemina  (Fig.  221);  the  cerebellum  tending  in  the  same 
way  to  grow  backward,  and  projecting  foriher  and  farther  over  the 


Formation  of  the  Cerebro- 
spinal Axis. — 1.  Vesicle  of 
the  hemispheres.  2.  Vesicle  of 
the  tubercula  quadrigemina.  3. 
Vesicle  of  the  medulla  oblongata. 


Fig. 
2 


219. 
3 


% 


and  spinal  cord. — 1. 
Hemispheres.  2.  Tu- 
bercula quadrigemi- 
na. 3.  Cerebellum. 
4.  Medulla  oblongata. 


NERVOUS    SYSTEM. 


541 


medulla  oblongata.     The  subsequent  history  of  the  development 
of  the  encephalon  is  little  more  than  a  continuation  of  the  same 

Fig.  221. 


F(KTAL  Pi«,  one  and  a  quai-tor  inch 
long. — 1.  Hemispheres.  2.  Tubercula. 
qnadrigemina.  3.  Cerebellum.  4.  Me- 
dulla oblongata. 


HnAn  OF  FcF.TAL  Pio.  tbrep  and  a 
half  inches  long. — 1.  Hemispheres.  3. 
Cerebellum.     4.  Medulla  oblongata. 


process ;  the  relative  dimensions  of  the  parts  constantly  changing, 
so  that  the  hemispheres  become,  in  the  adult  condition  (Fig.  222), 

Fig.  222. 


Bratx  of  .\DrLT  Pig. — 1.  Hemispheres.     3.  Cerebellum.     4.  Medulla  oblongata. 

the  largest  of  all  the  divisions  of  the  encephalon,  while  the  cere- 
bellum is  next  in  size,  and  covers  entirely  the  upper  portion  of  the 
medulla  oblongata.  The  surfaces,  also,  of  the  hemispheres  and 
cerebellum,  which  were  at  first  smooth,  become  afterward  convoluted ; 
increasing,  in  this  way,  still  farther  the  extent  of  their  nervous 
matter.  In  the  human  foetus,  these  convolutions  begin  to  appear 
about  the  beginning  of  the  fifth  month  (Longet),  and  grow  con- 
stantly deeper  and  more  abundant  during  the  remainder  of  foetal 
life. 

The  lateral  portions  of  the  brain  growing  at  the  same  time  more 
rapidly  than  that  which  is  situated  on  the  median  line,  they  soon 
project  on  each  side  outward  and  upward;  and,  by  folding  over 
against  each  other  in  the  median  line,  form  the  right  and  left  hemi- 
spheres, separated   from    each   other  by  the    longitudinal  fissure. 


542  DEVELOPMENT    OF    THE    EMBRYO. 

A  similar  process  of  growth  taking  place  in  tlie  spinal  cord  results 
in  the  formation  of  the  two  lateral  columns  and  the  anterior  and  pos- 
terior median  fissures  of  the  cord.  Elsewhere  the  median  fissure  is 
less  complete,  as,  for  example,  between  the  two  lateral  halves  of  the 
cerebellum,  the  two  optic  thalami  and  corpora  striata,  and  the  two 
tubercula  quadrigemina;  but  it  exists  everywhere,  and  marks  more 
or  less  distinctly  the  division  between  the  two  sides  of  the  nervous 
centres,  produced  by  the  excessive  growth  of  their  lateral  portions. 
In  this  way  the  whole  cerebro-spinal  axis  is  converted  into  a  double 
organ,  equally  developed  upon  the  right  and  left  sides,  and  partially 
divided  by  a  longitudinal  median  fissure. 

Organs  of  Special  Sense. —  The  eyes  are  formed  by  a  diverticulum 
which  grows  out  on  each  side  from  the  first  cerebral  vesicle.  This 
diverticulum  is  at  first  hollow,  its  cavity  communicating  with  that 
of  the  hemisphere.  Afterward,  the  passage  between  the  two  is  filled 
up  with  a  deposit  of  nervous  matter,  and  becomes  the  optic  nerve. 
The  globular  portion  of  the  diverticulum,  which  is  converted  into 
the  globe  of  the  eye,  has  a  very  thin  layer  of  nervous  matter  depo- 
sited upon  its  internal  surface,  which  becomes  the  retina;  the  rest 
of  its  cavity  being  occupied  by  a  gelatinous  semi-fluid  substance, 
the  vitreous  body.  The  crystalline  lens  is  formed  in  a  distinct  fol- 
licle, which  is  an  offshoot  of  the  integument,  and  becomes  partially 
imbedded  in  the  anterior  portion  of  the  globe  of  the  eye.  The 
cornea  also  is  originally  a  part  of  the  integument,  and  remains 
partially  opaque  until  a  very  late  period  of  development.  Its  tissue 
clears  up,  however,  and  becomes  perfectly  transparent,  shortly  be- 
fore birth. 

The  iris  is  a  muscular  septum  which  is  formed  in  front  of  the 
crystalline  lens,  separating  the  anterior  and  posterior  chambers  of 
the  aqueous  humor.  Its  central  opening,  which  afterward  becomes 
the  pupil,  is  at  first  closed  by  a  vascular  membrane,  the  pupillary 
membrane^  passing  directly  across  the  axis  of  the  eye.  The  vessels 
of  this  membrane,  which  are  derived  from  those  of  the  iris,  subse- 
quently become  atrophied.  They  disappear  first  from  its  centre, 
and  afterward  recede  gradually  toward  its  circumference;  returning 
always  upon  themselves  in  loops,  the  convexities  of  which  are  directed 
toward  the  centre  of  the  membrane.  The  pupillary  membrane  itself 
finally  becomes  atrophied  and  destroyed,  following  in  this  retro- 
grade process  the  direction  of  its  receding  bloodvessels,  viz.,  from 
the  centre.toward  the  circumference.  It  has  completely  disappeared 
by  the  end  of  the  seventh  month.  (Cruveilhier.) 


SKELETON    AND    LIMBS.  543 

The  eyelids  are  formed  by  folds  of  the  integument,  which 
gradually  project  from  above  and  below  the  situation  of  the  eye- 
ball. They  grow  so  rapidly  during  the  second  and  third  months 
that  their  free  margins  come  in  contact  and  adhere  together,  so  that 
they  cannot  be  separated  at  that  time  without  some  degree  of  vio- 
lence. They  remain  adherent  from  this  period  until  the  seventh 
month  (Guy),  when  their  margins  separate  and  they  become  per- 
fectly free  and  movable.  In  the  carnivorous  animals,  however 
(dogs  and  cats),  the  eyelids  do  not  separate  from  each  other  until 
eight  or  ten  days  after  birth. 

The  internal  ear  is  formed  in  a  somewhat  similar  manner  with 
the  eyeball,  by  an  oft'shoot  from  the  third  cerebral  vesicle;  the 
passage  between  them  filling  up  by  a  deposit  of  white  substance, 
which  becomes  the  auditory  nerve.  The  tympanum  and  auditory 
meatus  are  both  offshoots  from  the  external  integument. 

Skeleton. — At  a  very  early  period  of  development  there  appears, 
as  we  have  already  described  (Chap.  YIL),  immediately  beneath  the 
cerebro-spinal  axis,  a  cylindrical  cord,  of  a  soft,  cartilaginous  con- 
sistency, termed  the  chorda  dorsalis.  It  consists  of  a  fibrous  sheath 
containing  a  mass  of  simple  cells,  closely  packed  together  and 
united  by  adhesive  material.  This  cord  is  not  intended  to  be  a 
permanent  part  of  the  skeleton,  but  is  merely  a  temporary  organ 
destined  to  disappear  as  development  proceeds. 

Immediately  around  the  chorda  dorsalis  there  are  deposited  soon 
afterward  a  number  of  cartilaginous  plates,  which  encircle  it  in  a 
series  of  rings,  corresponding  in  number  with  the  bodies  of  the  future 
vertebrae.  These  rings  increase  in  thickness  from  without  inward, 
encroaching  upon  the  substance  of  the  chorda  dorsalis,  and  finally 
taking  its  place  altogether.  The  thickened  rings,  which  have  been 
filled  up  in  this  way  and  solidified  by  cartilaginous  deposit,  become 
the  bodies  of  the  vertebrae ;  while  their  transverse  and  articulating 
processes,  with  the  laminae  and  spinous  processes,  are  formed  by 
subsequent  outgrowths  from  the  bodies  hi  various  directions. 

When  the  union  of  the  dorsal  plates  upon  the  median  line  fails 
to  take  place,  the  spinal  canal  remains  open  at  that  situation,  and 
presents  the  malformation  known  as  spina  bifida.  This  malforma- 
tion may  consist  simply  in  a  fissure  of  the  spinal  canal,  more  or 
less  extensive,  in  which  case  it  may  often  be  cured,  or  even  close 
spontaneously;  or  it  may  be  complicated  with  an  imperfect  deve- 
lopment or  complete  absence  of  the  spinal  cord  at  the  same  spot. 


544  DEVELOPMENT    OF    THE    EMBRYO. 

when  it  is  accompanied  of  course  by  paralysis  of  the  lower  ex- 
tremities, and  almost  necessarily  results  in  early  death. 

The  entire  skeleton  is  at  first  cartilaginous.  The  first  points  of 
ossification  show  themselves  about  the  beginning  of  the  second 
month,  almost  simultaneously  in  the  clavicle  and  the  upper  and 
lower  jaw.  Then  come,  in  the  following  order,  the  long  bones  of 
the  extremities,  the  bodies  and  processes  of  the  vertebrae,  the  bones 
of  the  head,  the  ribs,  pelvis,  scapula,  metacarpus  and  metatarsus, 
and  the  phalanges  of  the  fingers  and  toes.  The  bones  of  the  carpus, 
however,  are  all  cartilaginous  at  birth,  and  do  not  begin  to  ossify 
until  a  year  afterward.  The  calcaneum  and  astragalus  begin  to 
ossify,  according  to  Cruveilhier,  during  the  latter  periods  of  foetal 
life,  but  the  remainder  of  the  tarsus  is  cartilaginous  at  birth.  The 
lower  extremity  of  the  femur  begins  to  ossify,  according  to  the 
same  author,  during  the  last  half  of  the  ninth  month.  The  pisiform 
bone  of  the  carpus  is  said  to  commence  its  ossification  later  than 
any  other  bone  in  the  skeleton,  viz.,  at  from  twelve  to  fifteen  years 
after  birth.  Nearly  all  the  bones  ossify  from  several  distinct  points ; 
the  ossification  spreading  as  the  cartilage  itself  increases  in  size, 
and  the  various  bony  pieces,  thus  produced,  uniting  with  each  other 
at  a  later  period,  usually  some  time  after  birth. 

The  limbs  appear,  by  a  kind  of  budding  process,  as  offshoots  of 
the  external  layer  of  the  blastodermic  membrane.  They  are  at 
first  mere  rounded  elevations,  without  any  separation  between  the 
fingers  and  toes,  or  any  distinction  between  the  different  articula- 
tions. Subsequently  the  free  extremity  of  each  limb  becomes  di- 
vided into  the  phalanges  of  the  fingers  or  toes ;  and  afterward  the 
articulations  of  the  wrist  and  ankle,  knee  and  elbow,  shoulder  and 
hip,  appear  successively  from  below  upward. 

The  posterior  extremities,  in  the  human  subject,  are  less  rapid  in 
their  development  than  the  anterior.  Throughout  the  term  of 
foetal  life,  indeed,  the  anterior  parts  of  the  body  are  generally  more 
voluminous  than  the  posterior.  The  younger  the  embryo,  the  larger 
are  the  head  and  upper  extremities  in  proportion  to  the  rest  of  the 
body.  The  lower  limbs,  and  the  pelvis  more  particularly,  are  very 
slightly  developed  in  the  early  periods  of  growth,  as  compared  with 
the  spinal  column,  to  which  they  are  attached.  The  inferior  ex- 
tremity of  the  spinal  column,  formed  by  the  sacrum  and  coccyx,  pro- 
jects at  this  time  considerably  beyond  the  pelvis,  forming  a  tail,  like 
that  of  the  lower  animals,  which  is  curled  forward  toward  the  ab- 
domen, and  terminates  in  a  pointed  extremity.     Subsequently  the 


SKELETON    AND    LIMBS.  545 

pelvis  and  the  muscular  parts  seated  upon  it  grow  so  much  faster 
than  the  sacrum  and  coccyx,  that  the  latter  become  concealed 
under  the  adjoining  soft  parts,  and  the  rudimentary  tail  accordingly 
disappears. 

The  integument  o^  the  embryo  is  at  first  thin,  vascular,  and  ex- 
ceedingly transparent.  It  afterward  becomes  thicker,  more  opaque, 
and  whitish  in  color;  though  even  at  birth  it  is  more  vascular  than 
in  the  adult  condition,  and  the  ruddy  color  of  its  abundant  capil- 
lary vessels  is  then  very  strongly  marked.  The  hairs  begin  to 
appear  about  the  middle  of  intra-uterine  life;  showing  themselves 
first  upon  the  eyebrows,  and  afterward  upon  the  scalp,  trunk  and 
extremities.  The  nails  are  in  process  of  formation  from  the  third 
to  the  fifth  month  ;  and,  according  to  Kolliker,  are  still  covered 
with  a  layer  of  epidermis  until  after  the  latter  period.  The  seba- 
ceous matter  of  the  cutaneous  glandules  accumulates  upon  the  skin 
after  the  sixth  month,  and  forms  a  whitish,  semisolid,  oleaginous 
layer,  termed  the  vernix  caseosa,  which  is  most  abundant  in  the 
flexures  of  the  joints,  between  the  folds  of  the  integument,  behind 
the  ears  and  upon  the  scalp. 

The  cells  of  the  epidermis  are  repeatedly  exfoliated  after  the  first 
five  months  of  foetal  life  (Kolliker),  and  replaced  by  others,  of  new 
formation  and  of  larger  size.  These  exfoliated  epidermic  cells  are 
found  mingled  with  the  sebaceous  matter  of  the  vernix  caseosa  in 
great  abundance.  This  semi-oleaginous  layer,  with  which  the  in- 
tegument is  covered,  becomes  exceedingly  useful  in  the  process  of 
parturition,  by  lubricating  the  surface  of  the  body,  and  allowing  it 
to  pass  easily  through  the  generative  passages. 


35 


546    DEVELOPMENT  OF  THE  ALIMENTARY  CANAL 


CHAPTER  XV. 

DEVELOPMENT  OF  THE  ALIMENTARY  CANAL  AND 
ITS  APPENDAGES. 

We  have  already  seen,  in  a  preceding  chapter,  that  the  intestinal 
canal  is  formed  by  the  internal  layer  of  the  blastodermic  membrane, 
which  curves  forward  on  each  side,  and  is  thus  converted  into  a 
nearly  straight  cylindrical  tube,  terminating  at  each  extremity  in 
a  rounded  cul-de-sac,  and  inclosed  by  the  external  layer  of  the 
blastodermic  membrane.  The  abdominal  walls,  however,  do  not 
unite  with  each  other  upon  the  median  line  until  long  after  the 
forjnation  of  the  intestinal  canal ;  so  that,  during  a  certain  period, 
the  abdomen  of  the  embryo  is  widely  open  in  front,  presenting  a 
long  oval  excavation,  in  which  the  nearly  straight  intestinal  tube 
is  to  be  seen,  running  from  its  anterior  to  its  posterior  extremity. 

The  formation  of  the  stomach  takes  place  in  the  following  man- 
ner :  The  alimentary  canal,  originally  straight,  soon  presents  two 
lateral  curvatures  at  the  upper  part  of  the  abdomen ;  the  first  to 
the  left,  the  second  to  the  right.  The  first  of  these  curvatures  be- 
comes expanded  into  a  wide  sac,  projecting  laterally  from  the 
median  line  into  the  left  hypochondrium,  forming  the  great  pouch 
of  the  stomach.  The  second  curvature,  directed  to  the  right,  marks 
the  boundary  between  the  stomach  and  the  duodenum;  and  the 
tube  at  that  point  becoming  constricted  and  furnished  with  a  circular 
layer  of  muscular  fibres,  is  converted  into  the  pylorus.  Immedi- 
ately below  the  pylorus,  the  duodenum  again  turns  to  the  left ;  and 
these  curvatures,  increasing  in  number  and  complexity,  form  the 
convolutions  of  the  small  intestine.  The  large  intestine  forms  a 
spiral  curvature ;  ascending  on  the  right  side,  then  crossing  over 
to  the  left  as  the  transverse  colon,  and  again  descending  on  the  left 
side,  to  terminate  by  the  sigmoid  flexure  in  the  rectum. 

The  curvatures  of  the  intestinal  canal  take  place,  however,  in  an 
antero-posterior,  as  well  as  in  a  lateral  direction,  and  may  be  best 
studied  in  a  profile  view,  as  in  Fig.  223.     The  abdominal  walls  are 


AND    ITS    APPENDAGES,  547 

here  still  imperfectly  closed,  leaving  a  wide  opening  at  a  h,  where 
the  integument  of  the  foetus  becomes  continuous  with  the  com- 
mencement of  the  amniotic  membrane.     The  intestine  makes  at 

Fiff.  223. 


Formation  of  Alimentary  Canal. — n,b.  Commeneement  of  amnion,  c,  c.  Intestine,  d. 
Pharynx,  e.  Uiinai y  bladder.  /.  Allautois.  g.  Umbilical  vesicle,  x.  Dotted  line,  showing  the 
place  of  formation  of  the  oesophagus. 

first  a  single  angular  turn  forward,  and  opposite  the  most  promi- 
nent portion  of  this  angle  is  to  be  seen  the  obliterated  duct,  which 
forms  the  stem  of  the  umbilical  vesicle.  A  short  distance  below 
this  point  the  intestine  subsequently  enlarges  in  its  calibre,  and  the 
situation  of  this  enlargement  marks  the  commencement  of  the 
colon.  The  two  portions  of  the  intestine,  after  this  period,  becomie 
widely  different  from  each  other.  The  upper  portion,  which  is  the 
small  intestine,  grows  mostly  in  the  direction  of  its-  length,  and  be- 
comes a  very  long,  convoluted,  and  narrow  tube;  while  the  lower 
portion,  which  is  the  large  intestine,  increases  rapidly  in  diameter, 
but  elongates  less  than  the  former. 

At  the  point  of  junction  of  the  small  and  large  intestines,  a  late- 
ral bulging  or  diverticulum  of  the  latter  shows  itself,  and  increases 
in  extent,  until  the  ileum  seems  at  last  to  be  inserted  obliquely  into 
the  side  of  the  colon.  This  diverticulum  of  the  colon  is  at  first  uni- 
formly tapering  or  conical  in  shape ;  but  afterward  that  portion 
which  forms  its  free  extremity,  becomes  narrow  and  elongated,  and 
is  slightly  twisted  upon  itself  in  a  spiral  direction,  forming  the  ap- 
pendix vermiformis;  while  the  remaining  portion,  which  is  con- 
tinuous with  the  intestine,  becomes  exceedingly  enlarged,  and  forms 
the  caput  coli. 

The  ciiput  coli  and  the  appendix  are  at  first  situated  near  the  um- 


548    DEVELOPMENT  OF  THE  ALIMENTARY  CANAL 

bilicus;  but  between  the  fourth  and  fifth  months  (Cruveilhier)  their 
position  is  altered,  and  they  then  become  fixed  in  the  right  iliac 
region.  During  the  first  six  months,  the  internal  surface  of  the 
small  intestine  is  smooth.  At  the  seventh  month,  according  to 
Cruveilhier,  the  valvulse  conniventes  begin  to  appear,  after  which 
they  increase  in  size  till  birth.  The  division  of  the  colon  into  sac- 
culi  by  longitudinal  and  transverse  bands,  is  also  an  appearance 
which  presents  itself  only  during  the  last  half  of  foetal  life.  Pre- 
vious to  that  time,  the  colon  is  smooth  and  cylindrical  in  figure, 
like  the  small  intestine. 

After  the  small  intestine  is  once  formed,  it  increases  very  rapidly 
in  length.  It  grows,  indeed,  at  this  time,  faster  than  the  walls  of 
the  abdomen;  so  that  it  can  no  longer  be  contained  in  the  abdominal 
cavity,  but  protrudes  under  the  form  of  an  intestinal  loop,  or  her- 
nia, from  the  umbilical  opening.  At  a  subsequent  period,  on  the 
contrary,  the  walls  of  the  abdomen  grow  more  rapidly  than  the 
intestine.  They  accordingly  gradually  envelop  the  hernial  protru- 
sion, and  at  last  inclose  it  again  in  the  cavity  of  the  abdomen. 

Owing  to  an  imperfect  development  of  the  abdominal  walls,  and 
an  imperfect  closure  of  the  umbilicus,  this  intestinal  protrusion, 
which  is  normal  during  the  early  stages  of  foetal  life,  sometimes 
remains  at  birth,  and  we  then  have  a  congenital  umbilical  hernia. 
As  the  parts  at  that  time,  however,  have  a  natural  tendency  to 
cicatrize  and  unite  with  each  other,  simple  pressure  is  generally 
effectual,  in  such  cases,  in  retaining  the  hernia  within  the  abdomen, 
and  in  producing  at  last  a  complete  cure. 

Urinary  Bladder^  Urethra,  &c. — It  will  be  recollected  that  very 
soon  after  the  formation  of  the  intestine,  a  vascular  outgrowth  takes 
place  from  its  posterior  portion,  which  gradually  protrudes  from  the 
open  walls  of  the  abdomen  in  front,  until  it  comes  in  contact  with 
the  external  investing  membrane  of  the  egg,  and  forms,  by  its  con- 
tinued growth  and  expansion,  the  allantois.  (Fig.  228,/.)  It  is  at 
first,  as  we  have  shown  above,  a  hollow  sac;  but,  as  it  spreads  out 
over  the  surface  of  the  investing  membrane  of  the  egg,  its  two 
opposite  walls  adhere  to  each  other,  so  that  its  cavity  is  obliterated 
at  this  situation,  and  it  is  thus  converted  into  a  single  vascular 
membrane,  the  chorion.  This  obliteration  of  the  cavity  of  the 
allantois  commences  at  its  external  portion,  and  gradually  extends 
inward  toward  the  point  of  its  emergence  from  the  abdomen.  The 
hollow  tube,  or  duct,  which  connects  the  cavity  of  the  allantois  with 
the  posterior  part  of  the  intestine,  is  accordingly  converted,  as  the 


AND    ITS    APPENDAGES.  549 

process  of  obliteration  proceeds,  into  a  solid,  rounded  cord.  This 
cord  is  termed  the  urachus. 

After  the  walls  of  the  abdomen  have  come  in  contact,  and  united 
with  each  other  at  the  umbilicus,  that  portion  of  the  above  duct 
which  is  left  outside  the  abdominal  cavity,  forms  a  part  of  the  um- 
bilical cord,  and  remains  connected  with  the  umbilical  arteries  and 
vein.  That  portion,  on  the  contrary,  which  is  included  in  the  ab- 
domen, does  not  close  completely,  but  remains  as  a  pointed  fusiform 
sac,  terminating  near  the  umbilicus  in  the  solid  cord  of  the  urachus, 
and  still  communicating  at  its  base  with  the  lower  extremity  of  the 
intestinal  canal.  This  fusiform  sac  (Fig.  223,  e),  becomes  the  wn- 
nary  bladder;  and  in  the  foetus  at  term,  the  bladder  is  still  conical 
in  form,  its  pointed  extremity  being  attached,  by  means  of  the  ura- 
chus, to  the  internal  surface  of  the  abdominal  walls  at  the  situation 
of  the  umbilicus.  Afterward,  the  bladder  loses  this  conical  form, 
and  its  fundus  in  the  adult  becomes  rounded  and  bulging. 

The  urinary  bladder,  as  it  appears  from  the  abov^e  description,  at 
first  communicates  freely  with  the  intestinal  cavity.  The  intestine, 
in  fact,  terminates,  at  this  time,  in  a  wide  passage,  or  cloaca,  at  its 
lower  extremity,  which  serves  as  a  common  outlet  for  the  urinary 
and  intestinal  passages.  Subsequently,  however,  a  horizontal  par- 
tition makes  its  appearance  just  above  the  point  of  junction  between 
the  bladder  and  rectum,  and  grows  downward  and  forward  in  such 
a  manner  as  to  divide  the  above-mentioned  cloaca  into  two  parallel 
and  unequal  passages.  The  anterior  or  smaller  of  these  passages 
becomes  the  urethra,  the  posterior  or  larger  becomes  the  rectum; 
and  the  lower  edge  of  the  septum  between  them  becomes  finally 
united  with  the  skin,  forming,  at  its  most  superficial  part,  a  tole- 
rably wide  band  of  integument,  the  perineum,  which  intervenes  be- 
tween the  anus  and  the  external  portion  of  the  urethra. 

The  contents  of  the  intestine,  which  accumulate  during  foetal  life, 
vary  in  different  parts  of  the  alimentary  canal.  In  the  small  intes- 
tine they  are  semifluid  or  gelatinous  in  consistency,  of  a  light 
yellowish  or  grayish- white  color  in  the  duodenum,  becoming  yellow, 
reddish-brown  and  greenish  brown  below.  In  the  large  intestine 
they  are  of  a  dark  greenish  hue,  and  pasty  in  consistency ;  and  the 
contents  of  this  portion  of  the  alimentary  canal  have  received  the 
name  of  meconium,  from  their  resemblance  to  inspissated  poppy- 
juice.  The  meconium  contains  a  large  quantity  of  fat,  as  well  as 
various  insoluble  substances,  probably  the  residue  of  epithelial  and 
mucous  accumulations.     It  does  not  contain,  however,  any  trace  of 


550     DEVELOPMEXT  OF  THE  ALIMEXTAEY  CAXAL 

the  biliary  substances  (tauro-cholatesand  glyko-cholates)  when  care- 
fallj  examined  by  Pettenkofer's  test ;  and  cannot  therefore  properly 
be  regarded,  as  is  sometimes  incorrectly  asserted,  as  resulting  from 
the  accumulation  of  bile.  In  the  contents  of  the  small  intestine,  on 
the  contrary,  traces  of  bile  may  be  found,  according  to  Lehmann,' 
so  early  as  between  the  fifth  and  sixth  months.  We  have  also 
found  distinct  traces  of  bile  in  the  small  intestine  at  birth,  but  it  is 
even  then  in  extremely  small  quantity,  and  is  sometimes  altogether 
absent. 

The  meconium,  therefore,  and  the  intestinal  contents  generally, 
are  not  composed  principally,  or  even  to  any  appreciable  extent,  of 
the  secretions  of  the  liver.  They  appear  rather  to  be  produced  by 
the  mucous  membrane  of  the  intestine  itself.  Even  their  yellowish 
and  greenish  color  does  not  depend  on  the  presence  of  bile,  since 
the  yellow  color  first  shows  itself,  in  very  3'Oung  foetuses,  tibout 
the  middle  of  the  small  intestine,  and  not  at  its  upper  extremity. 
The  material  which  accumulates  afterward  appears  to  extend  from 
this  point  upward  and  downward,  gradually  filling  the  intestine, 
and  becoming,  in  the  ileum  and  large  intestine,  darker  and  more 
pasty  as  gestation  advances. 

It  is  a  singular  fact,  perhaps  of  some  importance  in  this  connec- 
tion, that  the  amniotic  fluid,  during  the  latter  half  of  fcetal  life, 
finds  its  way,  in  greater  or  less  abundance,  into  the  stomach,  and 
through  that  into  the  intestinal  canal.  Small  cheesy-looking  masses 
may  sometimes  be  found  at  birth  in  the  fluid  contained  in  the 
stomach,  which  are  seen  on  microscopic  examination  to  be  no  other 
than  portions  of  the  vernix  caseosa  exfoliated  from  the  skin  into 
the  amniotic  cavity,  and  afterward  swallowed  into  the  stomach. 
According  to  Kcilliker,^  the  soft  downy  hairs  of  the  foetus,  exfoliated 
from  the  skin,  are  often  swallowed  in  the  same  way,  and  may  be 
found  in  the  meconium. 

The  gastric  juice  is  not  secreted  before  birth ;  the  contents  of  the 
stomach  being  generally  in  small  quantity,  clear,  nearly  colorless, 
and  neutral  or  alkaline  in  reaction. 

The  liver  is  developed  at  a  very  early  period.  Its  size  in  pro 
portion  to  that  of  the  entire  body  is,  in  fact,  very  much  greater  in 
the  early  months  than  at  birth  or  in  the  adult  condition.  In  the 
fcetal  pig  we  have  found  the  relative  size  of  the  liver  greatest 
within  the  first  month,  when  it  amounts  to  very  nearly  12  per  cent. 

'  Physiological  Chemistry,  Philadelphia  edition,  vol.  i.  p.  532. 
*  Gewebelehie.      Leipzig,  1852,  p.  139. 


AND    ITS    APPENDAGES.  551 

of  the  entire  weight  of  the  body.  Afterward,  as  it  grows  less  rapidly 
than  other  parts,  its  relative  weight  diminishes  successively  to  10 
per  cent,  and  6  per  cent. ;  and  is  reduced  before  birth  to  3  or  4  per 
cent.  In  the  human  subject,  also,  the  weight  of  the  liver  at  birth 
is  between  3  and  4  per  cent,  of  that  of  the  entire  body. 

The  secretion  of  hue  takes  place,  as  we  have  intimated  above, 
during  foetal  life,  in  a  very  scanty  manner.  "We  have  found  it,  in 
minute  quantity,  in  the  gall-bladder  as  well  as  in  the  small  intes- 
tine at  birth ;  but  it  does  not  probably  take  any  active  part  in  the 
nutritive  or  other  functions  of  the  foetus  before  that  period. 

The  glycogenic  function  of  the  liver  commences  during  foetal  life, 
and  at  birth  the  tissue  of  the  organ  is  abundantly  saccharine.  It  is 
remarkable,  however,  that  in  the  early  periods  of  gestation  sugar  is 
produced  in  the  foetus  from  other  sources  than  the  liver.  In  very 
young  foetuses  of  the  pig,  for  example,  both  the  allantoic  and 
amniotic  fluids  are  saccharine,  a  considerable  time  before  any  sugar 
makes  its  appearance  in  the  tissue  of  the  liver.  Even  the  urine,  in 
half  grown  foetal  pigs,  contains  an  appreciable  quantity  of  sugar, 
and  the  young  animal  is  therefore,  at  this  period,  in  a  diabetic  con- 
dition. This  sugar,  however,  disappears  from  the  urine  before  birth, 
and  also  from  the  amniotic  fluid,  as  has  been  ascertained  by  M.  Ber- 
nard;' while  the  liver  begins  to  produce  a  saccharine  substance,  and 
to  exercise  the  glycogenic  function,  which  it  continues  after  birth. 

Development  of  the  Pharynx,  (Esophagus,  &c. — We  have  already 
seen  that  the  intestinal  canal  consists  at  first  of  a  cylindrical  tube, 
terminated,  at  each  extremity  of  the  abdominal  cavity,  by  a  rounded 
cul-de-sac  (Fig.  223,  c,  c);  and  that  the  openings  of  the  mouth  and 
anus  are  subsequently  formed  by  perforations  which  take  place 
through  the  integument  and  the  intervening  tissues,  and  so  estab- 
lish a  communication  with  the  intestinal  tube.  The  formation  of 
the  anterior  perforation  and  its  appendages  takes  place  in  the  fol- 
lowing manner: — 

After  the  early  development  of  the  intestinal  tube  in  the  mode 
above  described,  the  head  increases  in  size  out  of  all  proportion  to 
the  remainder  of  the  foetus,  projecting  as  a  large  rounded  mass  from 
the  anterior  extremity  of  the  body,  and  containing  the  brain  and  the 
organs  of  special  sense.  This  portion  soon  bends  over  toward  the 
abdomen,  in  consequence  of  the  increasing  curvature  of  the  whole 
body  which   takes   place   at   this   time.     In  the  interior  of  this 

'  Lemons  de  Phjsiologie  ExpSrimentale,  Paris,  1855,  p.  398. 


552    DEVELOPMENT  OF  THE  ALIMENTARY  CANAL 

cephalic  mass  there  is  now  formed  a  large  cavity  (Fig.  223,  d\  by 
the  melting  down  and  liquefaction  of  a  portion  of  its  substance. 
This  cavity  is  the  pharynx.  It  corresponds  by  its  anterior  extre- 
mity to  the  future  situation  of  the  mouth;  and  by  its  posterior 
portion  to  the  upper  end  of  the  intestinal  canal,  the  future  situation 
of  the  stomach.  It  is  still,  however,  closed  on  all  sides,  and  does 
not  as  yet  communicate  either  with  the  exterior  or  with  the  cavity 
of  the  stomach.  There  is,  accordingly,  at  this  time,  no  thorax 
whatever;  but  the  stomach  lies  at  the  upper  extremity  of  the 
abdomen,  immediately  beneath  the  lower  extremity  of  the  pharynx, 
from  which  it  is  separated  by  a  wall  of  intervening  tissue. 

Subsequently,  a  perforation  takes  place  between  the  adjacent 
extremities  of  the  pharynx  and  stomach,  by  a  short  narrow  tube, 
the  situation  of  which  is  marked  by  the  dotted  lines  cc,  in  Fig.  223. 
This  tube  afterward  lengthens  by  the  rapid  growth  of  that  portion 
of  the  body  in  which  it  is  contained,  and  becomes  the  oesophagus. 
Neither  the  pharynx  nor  oesophagus,  therefore,  are,  properly  speak- 
ino-,  parts  of  the  intestinal  canal,  formed  from  the  internal  layer  of 
the  blastodermic  membrane;  but  are,  on  the  contrary,  formations 
of  the  external  layer,  from  which  the  entire  cephalic  mass  is  pro- 
duced. The  lining  membrane  of  the  pharynx  and  oesophagus  is 
to  be  regarded,  also,  for  the  same  reason,  as  rather  a  continuation 
of  the  integument  than  of  the  intestinal  mucous  membrane;  and 
even  in  the  adult,  the  thick,  whitish,  and  opaque  pavement  epithe- 
lium of  the  oesophagus  may  be  seen  to  terminate  abruptly,  by  a 
well-defined  line  of  demarcation,  at  the  cardiac  orifice  of  the  sto- 
mach ;  beyond  which,  throughout  the  remainder  of  the  alimentary 
canal,  the  epithelium  is  of  the  columnar  variety,  and  easily  dis- 
tinguishable by  its  soft,  ruddy,  and  transparent  appearance. 

As  the  oesophagus  lengthens,  the  lungs  are  developed  on  each 
side  of  it  by  a  protrusion  from  the  pharynx,  which  extends  and 
becomes  repeatedly  subdivided,  forming  the  bronchial  tubes  and 
their  ramifications.  At  first,  the  lungs  project  into  the  upper 
part  of  the  abdominal  cavity;  for  there  is  still  no  distinction  be- 
tween the  chest  and  abdomen.  Afterward,  a  horizontal  partition 
begins  to  form  on  each  side,  at  the  level  of  the  base  of  the  lungs, 
which  gradually  closes  together  at  a  central  point,  so  as  to  form 
the  diaphragm,  and  finally  to  shut  off  altogether  the  cavity  of 
the  chest  from  that  of  the  abdomen.  Before  the  closure  of  the 
diaphragm,  thus  formed,  is  complete,  a  circular  opening  exists  on 
each  side  the  median  line,  by  which  the  peritoneal  and  pleural 


AND    ITS    APPENDAGES, 


553 


cavities  communicate  with  each  other.  In  some  instances  the  de- 
velopment of  the  diaphragm  is  arrested  at  this  point,  either  on  one 
side  or  the  other,  and  the  opening  accordingly  remains  permanent. 
The  abdominal  organs  then  partially  protrude  into  the  cavity  of 
the  chest  on  that  side,  forming  congenital  diaphragmatic  hernia. 
The  lung  on  the  affected  side  also  usually  remains  in  a  state  of 
imperfect  development.  Diaphragmatic  hernia  of  this  character  is 
more  frequently  found  upon  the  left  side  than  upon  the  right.  It 
may  sometimes  continue  until  adult  life  without  causing  any  serious 
iuconvenience. 

The  heart  is  formed,  at  a  very  early  period,  directly  in  front  of 
the  situation  of  the  oesophagus.  Its  size  soon  becomes  very  large 
in  proportion  to  the  rest  of  the  body;  so  that  it  protrudes  beyond 
the  level  of  the  thoracic  parietes,  covered  only  by  the  pericardium. 
Subsequently,  the  walls  of  the  thorax,  becoming  more  rapidly 
developed,  grow  over  it  and  inclose  it.  In  certain  instances,  how- 
ever, they  fail  to  do  so,  and  the  heart  then  remains  partially  or 
completely  uncovered,  in  front  of  the  chest,  presenting  the  condi- 
tion known  as  ectopia  cordis.  This  malformation  is  necessarily 
fatal. 

Development  of  the  Face. — While  the  lower  extremity  of  the 
pharynx  communicates  with  the  cavity  of  the  stomach,  as  above 
described,  its  upper  extremity  also  becomes  perforated  in  a  similar 
manner,  and  establishes  a  communication  with  the  exterior.  This 
perforation  is  at  first  wide  and  gaping.  It  afterward  becomes 
divided  into  the  mouth  and  nasal  passages;  and  the  different  parts 
of  the  face  are  formed  round  it  in  the  following  manner: — 

From  the  sides  of  the  cephalic  mass 
five  buds  or  processes  shoot  out,  and 
grow  toward  each  other,  so  as  to  approach 
the  centre  of  the  oral  orifice  above  men- 
tioned. (Fig.  224.)  One  of  them  grows 
directly  downward  from  the  frontal  region 
(i),  and  is  called  the  frontal  or  inter- 
maxillary process,  because  it  afterward 
contains  in  its  lower  extremity  the  inter- 
maxillary  bones,  in   which    the   incisor 

HeadofHumaxEmbryo, 

teeth  of  the  upper  jaw  are  inserted.     The     at  about  the  twentieth  day.  After 
next  process  (2)  originates  from  the  side     ^"°^''=  ^'■°™  ^  specimen  iu  the 

^  ^     ^    ^  °  collection  of  M.Coste.—l.  Frontal 

of  the  opening,  and,  advancing  toward  the        or  intermaxillary  process.   2.  Pro- 

median  line,  forms,  with  its  fellow  of  the     -- of  ^yi-io-- "-^;>'-  s-  i'^^- 

'  '  cess  of  inferior  maxiUa. 


Fig.  224. 


554 


DEVELOPMENT  OF  THE  ALIMENTAKY  CANAL 


opposite  side,  the  superior  maxilla.  The  processes  of  the  remain- 
ing pair  (3)  also  grow  from  the  side,  and  form,  by  their  subsequent 
union  upon  the  median  line,  the  inferior  maxilla.  The  inferior 
maxillary  bone  is  finally  consolidated,  in  man,  into  a  single  piece, 
but  remains  permanently  divided,  in  the  lower  animals,  by  a  suture 
upon  the  median  line. 

As  the  frontal  process  grows  from  above 
downward,  it  becomes  double  at  its  lower 
extremity  (Fig.  225),  and  at  the  same  time 
two  offshoots  show  themselves  upon  its 
sides  (1),  which  curl  round  and  inclose  two 
circular  orifices  (5),  the  opening  of  the  an- 
terior nares;  the  offshoots  themselves  be- 
coming the  alas  nasi. 

The  processes  of  the  superior  maxilla 
continue  their  growth,  but  less  rapidly  than 
those  of  the  inferior ;  so  that  the  two  sides 
of  the  lower  jaw  are  already  consolidated 
with  each  other,  while  those  of  the  upper 
jaw  are  still  separate. 

As  the  processes  of  the  superior  maxilla 
continue  to  enlarge,  they  also  tend  to  unite 
with  each  other  on  the  median  line,  but  are 
prevented  from  doing  so  by  the  intermax- 
illary processes  which  grow  down  between 
them.  They  then  unite  with  the  inter- 
maxillary processes,  which  have  at  the  same  time  united  with  each 
other,  and  the  upper  jaw  and  lip  are  thus  completed.     (Fig.  226.) 

The  external  edge  of  the  ala  nasi  also 
adheres  to  the  superior  maxillary  pro- 
cess and  unites  with  it,  leaving  only  a 
curved  crease  or  furrow,  as  a  sort  of 
cicatrix,  to  mark  the  line  of  union  be- 
tween them. 

Sometimes  the  superior  maxillary 
and  the  intermaxillary  processes  fail  to 
unite  with  each  other;  and  we  then 
have  the  malformation  known  as  hare- 
lip. The  fissure  of  hare-lip,  conse- 
TiEAD  OF  Human  Embryo,  about    queutly,  is  ncvcr  cxactly  in  the  median 

tbo  end  of  the  second  month —From  a      ,.  i       t    „    i;<.*.1„    4.^     ^v^^    c,\A^    ^P   if    ,->ti 

.,    ,  line,  but  a  little  to  one  side  oi  it,  on 

specimen  in  the  author's  possession.  iiuc,    uliu    c*    i.tvi,i.^    uv.    vy     v/  , 


Head  of  Human  Embryo 
at  the  end  of  the  first  month. 
After  Longet ;  from  a  specimen 
in  the  collection  of  M.  Co-^te  — 
].  AUnasi.  2.  Superior  maxilla. 
.3.  Inferior  maxilla.  4.  Inter- 
maxillary process.  0.  Nostril. 
6.  Eye. 


226. 


AND    ITS    APPENDAGES.  555 

the  external  edge  of  the  intermaxillary  process.  Occasionally,  the 
same  deficiency  exists  on  both  sides,  producing  "double  hare-lip;" 
in  which  case,  if  the  fissures  extend  through  the  bony  structures, 
the  central  piece  of  the  superior  maxilla,  which  is  detached  from 
the  remainder,  contains  the  four  upper  incisor  teeth,  and  corres- 
ponds with  the  intermaxillary  bone  of  the  lower  animals. 

The  eyes  at  an  early  period  are  situated  upon  the  sides  of  the 
head,  so  that  they  cannot  be  seen  in  an  anterior  view.  (Fig.  224.) 
As  development  proceeds,  they  come  to  be  situated  farther  forward 
(Fig.  225),  their  axes  being  divergent  and  directed  obliquely  for- 
ward and  outward.  At  a  later  period  still  they  are  placed  on  the 
anterior  plane  of  the  face  (Fig.  226)  and  have  their  axes  nearly 
parallel  and  looking  directly  forward.  This  change  in  the  situa- 
tion of  the  eyes  is  effected  by  the  more  rapid  growth  of  the  pos- 
terior and  lateral  parts  of  the  head,  which  enlarge  in  such  a  manner 
as  to  alter  the  relative  position  of  the  parts  seated  in  front  of  them. 

The  palate  is  formed  by  a  septum  between  the  mouth  and  nares, 
which  arises  on  each  side  as  a  horizontal  plate  or  offshoot  from  the 
superior  maxilla.  These  two  plates  afterward  unite  with  each 
other  upon  the  median  line,  forming  a  complete  partition  between 
the  oral  and  nasal  cavities.  The  right  and  left  nasal  passages  are 
also  separated  from  each  other  by  a  vertical  plate  (vomer),  which 
grows  from  above  downward  and  fuses  with  the  palatal  plates  be- 
low. Fissure  of  the  palate  is  caused  by  a  deficiency,  more  or  less 
complete,  of  one  of  the  horizontal  maxillary  plates.  It  is  accord- 
ingly situated  a  little  to  one  side  of  the  median  line,  and  is  fre- 
quently associated  with  hare-lip  and  fissure  of  the  upper  jaw.  The 
fissures  of  the  palate  and  the  lip  are  very  often  continuous  with 
each  other. 

The  anterior  and  posterior  pillars  of  the  fauces  are  incomplete 
vertical  partitions,  which  grow  from  the  sides  of  the  oral  cavity, 
and  tend  to  separate,  by  a  slight  constriction,  the  cavity  of  the 
mouth  from  that  of  the  pharynx. 

When  all  the  above  changes  are  accomplished,  the  pharynx, 
oesophagus,  mouth,  nares,  and  fauces,  with  their  various  projections 
and  divisions,  have  been  successively  formed;  and  the  development 
of  the  upper  part  of  the  alimentary,  canal  is  then  complete. 


556 


DEVELOPMENT  OF  THE  KIDNEYS. 


CHAPTER  XVI. 

DEVELOPMENT  OF  THE  KIDNEYS,  WOLFFIAN 
BODIES,  AND  INTERNAL  ORGANS  OF  GENE- 
RATION. 


The  first  trace  of  a  urinary  apparatus  in  the  embryo,  consists  of 
two  long,  fusiform  bodies,  which  make  their  appearance  in  the  ab- 
domen at  a  very  early  period,  situated  on  each  side  the  spinal 
column.  I^ese  are  known  by  the  name  of  the  Wolffian  bodies. 
They  are  fully  formed,  in  the  human  subject,  toward  the  end  of  the 
first  month  (Coste),  at  which  time  they  are  the  largest  organs  in  the 
cavity  of  the  abdomen,  extending  from  just  below  the  heart,  nearly 
to  the  posterior  extremity  of  the  body.  In  the  foetal  pig,  when  a 
little  over  half  an  inch  in  length  (Fig.  227),  the  Wolffian  bodies  are 
rounded  and  kidney-shaped,  and  occupy  a  very  large  part  of  the 
abdominal  cavity.  Their  importance  may  be  estimated  from  the 
fact  that  their  weight  at  this  time  is  equal  to 
a  little  over  -3-^3  of  that  of  the  entire  body — a 
proportion  which  is  seven  or  eight  times  as 
large  as  that  of  the  kidneys,  in  the  adult 
condition.  There  are,  indeed,  at  this  period, 
only  three  organs  perceptible  in  the  abdo- 
men, viz.,  the  liver,  which  has  begun  to  be 
formed  at  the  upper  part  of  the  abdominal 
cavity;  the  intestine,  which  is  already  some- 
what convoluted,  and  occupies  its  central 
portion  ;  and  the  Wolffian  bodies,  which  pro- 
ject on  each  side  the  spinal  column. 

The  WolflBan  bodies,  in  their  intimate 
structure,  resemble  very  closely  the  adult 
kidney.  They  consist  of  secreting  tubules, 
lined  with  epithelium,  which  run  from  the 
outer  toward  the  inner  edge  of  the  organ,  terminating  at  their  free 
extremities  in  small  rounded  dilatations,  or  culs-de-sac.     Into  each 


FfETALPiu,  5^  of  an  inch 
long;  from  a  specimen  in  the 
autlior's  possession.  1.  Heart. 
2.  Anterior  extremity.  3.  Pos- 
terior extremity.  4.  Wolfiian 
body  The  abdominal  walls 
have  been  cut  away,  in  order 
to  show  the  position  of  the 
Wolffian  bodies 


WOLFFIAN    BODIES.  557 

of  these  dilated  extremities  is  received  a  globular  coil  of  capillary 
bloodvessels,  or  glomerulus,  similar  to  that  of  the  adult  kidney. 
The  tubules  of  the  Wolffian  body  all  empty  into  a  common  excre- 
tory duct,  which  leaves  the  organ  at  its  lower  extremity,  and  com- 
municates afterward  with  the  lower  part  of  the  intestinal  canal,  just 
at  the  point  where  the  diverticulum  of  the  allantois  is  given  off",  and 
where  the  urinary  bladder  is  afterward  to  be  situated.  The  prin- 
cipal, if  not  the  only  distinction,  between  the  minute  structure  of 
the  Wolffian  bodies  and  that  of  the  true  kidneys,  consists  in  the 
size  of  the  tubules  and  of  their  glomeruli,  these  elements  being 
considerably  larger  in  the  Wolffian  body,  than  in  the  kidney.  In 
the  foetal  pig,  for  example,  about  an  inch  and  a  half  in  length,  the 
diameter  of  the  tubules  of  the  Wolffian  body  is  5^^  of  an  inch, 
while  in  the  kidney  of  the  same  foetus,  the  diameter  of  the  tubules 
is  only  ^i^  of  an  inch.  The  glomeruli  in  the  Wolffian  bodies 
measure  ^'^  of  an  inch  in  diameter,  wbile  those  of  the  kidney  mea- 
sure only  y|  0  of  an  inch.  The  Wolffian  bodies  are  therefore  urinary 
organs,  so  far  as  regards  their  anatomical  structure,  and  are  some- 
times known,  accordingly,  by  the  name  of  the  "false  kidneys." 
There  is  little  doubt  that  they  perform,  at  this  early  period,  a  func- 
tion analogous  to  that  of  the  kidneys,  and  separate  from  the  blood 
of  the  embryo  an  excrementitious  fluid  which  is  discharged  by  the 
ducts  of  the  organ  into  the  cavity  of  the  allantois. 

Subsequently,  the  Wolffian  bodies  increase  for  a  time  in  size, 
though  not  so  rapidly  as  the  rest  of  the  body;  and  consequently 
their  relative  magnitude  diminishes.  Still  later,  they  begin  to 
suffer  an  absolute  diminution  or  atrophy,  and  become  gradually 
less  and  less  perceptible.  In  the  human  subject,  they  are  hardlv 
to  be  detected  after  the  end  of  the  second  month  (Longet),  and  in 
the  quadrupeds  also  they  disappear  completely  long  before  birth. 
They  are  consequently  foetal  organs,  destined  to  play  an  important 
part  during  a  certain  stage  of  development,  but  to  become  after- 
ward atrophied  and  absorbed,  as  the  physiological  condition  of  the 
foetus  alters.  During  the  period,  however,  of  their  retrogression 
and  atrophy,  other  organs  appear  in  their  neighborhood,  which 
become  afterward  permanently  developed.  These  are,  first,  the 
kidneys,  and  secondly,  the  internal  organs  of  generation. 

The  kidneys  are  formed  just  behind  the  Wolffian  bodies,  and  are 
at  first  entirely  concealed  by  them  in  a  front  view,  the  kidneys 
being  at  this  time  not  more  than  a  fourth  or  a  fifth  part  the  size  of 


558 


DEVELOPMENT  OF  THE  KIDNEYS. 


FfETAL  PiQ,  one  and  a  half 
inches  long.  From  a  specimen  in 
the  author's  possession. — 1.  Wolffian 
body.     2.  Kidney. 


the  Wolffian  bodies.  (Fig.  228.)  As  the  kidneys,  however,  subse- 
quently enlarge,  while  the  Wolffian  bodies  diminish,  the  propor- 
tions existing  between  the  two  organs  are 
reversed;  and  the  Wolffian  bodies  at  last 
come  to  be  mere  small  rounded  or  ovoid 
masses,  situated  on  the  anterior  surface 
of  the  kidneys.  (Figs.  229  and  230.)  The 
kidneys,  during  this  period,  grow  more 
rapidly  in  an  upward  than  in  a  downward 
direction,  so  that  the  Wolffian  bodies 
come  to  be  situated  near  their  inferior 
extremity,  and  seem  to  have  performed 
a  sliding  movement  from  above  down- 
ward, over  their  anterior  surface.  This 
apparent  sliding  movement,  or  descent 
of  the  AYolffian  bodies,  is  owing  entirely 
to  the  rapid  growth  of  the  kidneys  in  an 
upward  direction,  as  we  have  already  explained. 

The  kidneys,  during  the  succeeding  periods  of  foetal  life,  become 
in  their  turn  very  largely  developed  in  proportion  to  the  rest  of 
the  organs;  attaining  a  size,  in  the  foetal  pig,  equal  to  ^^  (in  weight) 
of  that  of  the  entire  body.  This  proportion,  however,  diminishes 
again  very  considerably  before  birth,  owing  to  the  increased  deve- 
lopment of  other  parts.  In  the  human  foetus  at  birth,  the  weight 
of  the  two  kidneys  taken  together  is  y^g  that  of  the  entire  body. 
.  Internal  Organs  of  Generation. — About  the  same  time  that  the  kid- 
neys are  formed  behind  the  Wolffian  bo- 
dies, two  oval  shaped  organs  make  their 
appearance  in  front,  on  the  inner  side  of 
the  Wolffian  bodies  and  between  them  and 
the  spinal  column.  These  bodies  are  the 
internal  organs  of  generation ;  viz.,  the 
testicles  in  the  male,  and  the  ovaries  in 
the  female.  At  first  they  occupy  pre- 
cisely the  same  situation  and  present 
precisely  the  same  appearance,  whether 
IXT.RXAT.OROAXS  OF  nK>-K-    tijgfoetus  Is  aftcrwardto  belong  to  the 

KATioN,  &c.  ;  lu  a  foetal  pig  three  ° 

inches  long.    From  a  specimen  in  the     male  Or  the  fcmalc  SCX.    (Fig.  229.) 
author's  Possession. — 1,1.    Kidneys.  \        ^         i.     j-    i.  i,  j.i  •     j.  ^ 

2,2.  Wolffian  bodies.  .3,3.  Internal        ^  ^hort  distancc  abovc  thc    mtcmal 
organsofgeneration;  testicles  or  ova-   orgaDS  of  generation  there  commenccs, 

ries.    4.  Urinary  bladder,  turned  over  i  •  i  ,     i  i        j 

iu  front.  5. -Intestine.  ou    cach   Side,  a    narrow  tube   or  duct, 


MALE  ORGANS  OF  GENERATION.  559 

which  runs  from  above  downward  along  the  anterior  border  of  the 
Wolffian  body,  immediately  in  front  of  and  parallel  with  the  excre- 
tory duct  of  this  organ.  The  two  tubes,  right  and  left,  then  approach 
each  other  below;  and,  joining  upon  the  median  line,  empty,  together 
with  the  ducts  of  the  Wolffian  bodies,  into  the  base  of  the  allantois, 
OT  what  will  afterward  be  the  base  of  the  urinary  bladder.  These 
tubes  serve  as  the  excretory  ducts  of  the  internal  organs  of  genera- 
tion ;  and  will  afterward  become  the  vasa  deferentia  in  the  male,  and 
the  Fallopian  tubes  in  the  female.  According  to  Coste,  the  vasa  de- 
ferentia at  an  early  period  are  disconnected  with  the  testicles ;  and 
originate,  like  the  Fallopian  tubes,  by  free  extremities,  presenting 
each  an  open  orifice.  It  is  only  afterward,  according  to  the  same 
author,  that  the  vasa  deferentia  become  adherent  to  the  testicles,  and 
a  communication  is  established  between  them  and  the  tubuli  serni- 
niferi.  In  the  female,  the  Fallopian  tubes  remain  permanently 
disconnected  with  the  ovaries,  except  by  the  edge  of  the  fimbriated 
extremity ;  which  in  many  of  the  lower  animals  becomes  closely 
adherent  to  the  ovary,  and  envelopes  it  more  or  less  completely. 

Male  Organs  of  Generation  ;  Descent  of  the  Testicles. — In  the  male 
foetus  there  now  commences  a  movement  of  translation,  or  change 
of  place,  in  the  internal  organs  of  generation,  which  is  known  as 
the  "  descent  of  the  testicles."  In  consequence  of  this  movement, 
the  above  organs,  which  are  at  first  placed  near  the  middle  of  the 
abdomen,  and  directly  in  front  of  the  kidneys,  come  at  last  to  be 
situated  in  the  scrotum,  altogether  outside  and  below  the  abdominal 
cavity.  They  also  become  inclosed  in  a  distinct  serous  sac  of  their 
own,  the  tunica  vaginalis  testis.  This  apparent  movement  of  the 
testicles  is  accomplished  in  the  same  manner  as  that  of  the  Wolf- 
fian bodies,  above  mentioned,  viz.,  by  a  disproportionate  growth  of 
the  middle  and  upper  portions  of  the  abdomen  and  of  the  organs 
situated  above  the  testicles,  so  that  the  relative  position  of  these  or- 
gans becomes  altered.  The  descent  of  the  testicles  is  accompanied 
by  certain  other  alterations,  in  the  organs  themselves  and  their  ap- 
pendages, which  take  place  in  the  following  manner. 

By  the  upward  enlargement  of  the  kidneys,  both  the  Wolffian 
bodies  and  the  testicles  are  soon  found  to  be  situated  near  the 
lower  extremity  of  these  organs.  (Fig.  230.)  At  the  same  time,  a 
slender  rounded  cord  (not  represented  in  the  figure)  passes  from 
the  lower  extremity  of  each  testicle  in  an  outward  and  downward 
direction,  crossing  the  corresponding  vas  deferens  a  short  distance 
above  its  union  with  its  fellow  of  the  opposite  side.     Below  this 


660 


DEVELOPMENT  OF  THE  KIDNEYS. 


Internal  Organs  of  Generation, 
&c  ,  in  a  foetal  pig  nearly  four  inches  long. 
From  a  specimen  in  the  author's  possession. — 
1,  1  Kidneys.  2,  2.  Wolffian  bodies.  3,  3. 
Testicles.     4.  Urinary  bladder.     5.  Intestine. 


converted  into  the  epididymis. 


point,  the  cord  spoken  of  continues  to  run  obliquely  outward  and 
downward ;  and,  passing  through  the  abdominal  walls  at  the  situ- 
ation of  the  inguinal  canal,  is  inserted  into  the  subcutaneous  tissues 

near  the  symphysis  pubis.  The 
lower  part  of  this  cord  becomes 
the  gubernaculum  testis ;  and  mus- 
cular fibres  are  soon  developed  in 
its  substance  which  may  be  easily 
detected,  even  in  the  human  foetus, 
during  the  latter  half  of  gestation. 
At  the  period  of  birth,  however, 
or  soon  afterward,  these  muscular 
fibres  disappear  and  can  no  longer 
be  recognized. 

All  that  portion  of  the  excre- 
tory tube  of  the  testicle  which  is 
situated  outside  the  crossing  of  the 
gubernaculum,  is  destined  to  be- 
come afterward  convoluted,  and 
That  portion  which  is  situated  in- 
side the  same  point  remains  comparatively  straight,  but  becomes 
considerably  elongated,  and  is  finally  known  as  the  vas  deferens. 

As  the  testicles  descend  still  farther  in  the  abdomen,  they  con- 
tinue to  grow,  while  the  Wolffian  bodies,  on  the  contrary,  diminish 
rapidly  in  size,  until  the  latter  become  much  smaller  than  the  tes- 
ticles ;  and  at  last,  when  the  testicles  have  arrived  at  the  internal 
inguinal  ring,  the  Wolffian  bodies  have  altogether  disappeared,  or 
at  least  have  become  so  much  altered  that  their  characters  are  no 
longer  recognizable.  In  the  human  foetus,  the  testicles  arrive  at 
the  internal  inguinal  ring,  about  the  termination  of  the  sixth  month 
(Wilson). 

During  the  succeeding  month,  a  protrusion  of  the  peritoneum 
takes  place  through  the  inguinal  canal,  in  advance  of  the  testicle ; 
while  the  last  named  organ  still  continues  its  descent.  As  it  then 
passes  downward  into  the  scrotum,  certain  muscular  fibres  are  given 
off  from  the  lower  border  of  the  internal  oblique  muscle  of  the 
abdomen,  growing  downward  with  the  testicle,  in  such  a  manner  as 
to  form  a  series  of  loops  upon  it,  and  upon  the  elongating  spermatic 
cord.     These  loops  constitute  afterward  the  cremaster  muscle. 

At  last,  the  testicle  descends  fairly  to  the  bottom  of  the  scrotum, 
the   gubernaculum   constantly  shortening,   and   the   vas   deferens 


MALE  ORGANS  OF  GENERATION". 


561 


elongating  as  it  proceeds.  The  convoluted  portion  of  the  efferent 
duct,  viz.,  the  epididymis,  then  remains  closely  attached  to  the  body 
of  the  testicle ;  while  the  vas  deferens  passes  upward,  in  a  reverse 
direction,  enters  the  abdomen  through  the  inguinal  canal,  again 
bends  downward,  and  joins  its  fellow  of  the  opposite  side;  after 
which  they  both  open  into  the  prostatic  portion  of  the  urethra, 
upon  the  median  line,  by  a  common  orifice  (sinus  pocularis).  At 
the  same  time,  two  diverticula  arise  from  the  median  portion  of  the 
vasa  deferentia,  and,  elongating  in  a  backward  direction,  underneath 
the  base  of  the  bladder,  become  developed  into  two  compound 
sacculated  reservoirs — the  vesiculoe  seminales. 

The  left  testicle  is  a  little  later  in  its  descent  than  the  right,  but 
it  afterward  passes  farther  into  the  scrotum,  and,  in  the  adult  condi- 
tion, usually  hangs  a  little  lower  than  its  fellow  of  the  opposite  side. 

After  the  testicle  has  fairly  passed  into  the  scrotum,  the  serous 
pouch,  which  preceded  its  descent,  remains  for  a  time  in  communi- 
cation with  the  peritoneal  cavity.  In  many  of  the  lower  animals, 
as,  for  example,  the  rabbit,  this  condition  is  permanent ;  and  the 
testicle,  even  in  the  adult  animal,  may  be  alternately  drawn  down- 
ward into  the  scrotum,  or  retracted  into  the  abdomen,  by  the  action 
of  the  gubernaculum  and  the  cremaster  muscle.  But  in  the  human 
foetus,  the  two  opposite  surfaces  of  the  peritoneal  pouch,  covering 
the  testicle,  approach  each  other  at  the  inguinal  canal,  forming  at 
that  point  a  constriction  or  neck,  which  partly  shuts  off  the  testicle 
from  the  cavity  of  the  abdomen.  By  a 
continuation  of  this  process,  the  serous 
surfaces  come  actually  in  contact  with 
each  other,  and,  adhering  together  at 
this  situation  (Fig.  281,  4),  form  a  kind 
of  cicatrix,  or  umbilicus,  by  the  complete 
closure  and  consolidation  of  which  the 
cavity  of  the  tunica  vaginalis  (2)  is  finally 
shut  off  altogether  from  the  general  cavity 
of  the  peritoneum  (3).  The  tunica  vagi- 
nalis testis  is,  therefore,  originally  a  part 
of  the  peritoneum,  from  which  it  is  sub- 
sequently separated  by  the  process  just 
described. 

The  separation  of  the  tunica  vaginalis 
from  the  peritoneum  is  usually  completed 

in  the  human  subject  before  birth.     But  sometimes  it  fails  to  take 
36 


Fig.  231. 


Formation  of  Tunica  Va- 
ginalis Testis.— 1.  Testicle^ 
nearly  at  the  bottom  of  the  scro- 
tum. 2.  Cavity  of  tunica  Tdginali.K, 
3.  Cavity  of  peritoneum.  4.  Obliter- 
ated neck  of  peritoneal  sac. 


562        DEVELOPMENT  OF  THE  KIDNEYS,  ETC. 

place  at  the  proper  time,  and  the  intestine  is  then  apt  to  protrude 
into  the  scrotum,  in  front  of  the  spermatic  cord,  giving  rise,  in  this 
way,  to  a  congenital  inguinal  hernia.  (Fig.  232.)  The  parts  impli- 
cated, however,  in  this  malformation,  have 
^^'  still,  as  in  the  case  of  congenital  umbili- 

cal hernia,  a  tendency  to  unite  with  each 
other  and  obliterate  the  unnatural  open- 
ings ;  and  if  the  intestine  be  retained  by 
pressure  in  the  cavity  of  the  abdomen, 
cicatrization  usually  takes  place  at  the 
inguinal  canal,  and  a  cure  is  effected. 

The  descent  of  the  testicle,  above  de- 
scribed, is  not  accomplished  by  the  forci- 
ble traction  of  the  muscular  fibres  of  the 
co.v<iE. VITAL  Inguinal  hee-     g-ubemaculum,  as  has  been  described  bv 

.VIA.— 1.   Testicle.      2,  2,  2.    Intes-        °  .  ■  i  i  •  i 

tine.  certam  writers,  but  by  a  simple  process 

of  growth  taking  place  in  different  parts, 
in  different  directions,  at  successive  periods  of  foetal  life.  The 
gubernaculum,  accordingly,  has  no  proper  function  as  a  muscular 
organ,  in  the  human  subject,  but  is  merely  the  anatomical  vestige, 
or  analogue,  of  a  corresponding  muscle  in  certain  of  the  lower 
animals,  where  it  has  really  an  important  function  to  perform.  For 
in  them,  as  we  have  already  mentioned,  both  the  gubernaculum 
and  the  cremaster  remain  fully  developed  in  the  adult  condition, 
and  are  then  employed  to  elevate  and  depress  the  testicle,  by  the 
alternate  contraction  of  their  muscular  fibres. 

Female  Organs  of  Generation. — At  an  early  period,  as  we  have 
mentioned  above,  the  ovaries  have  the  same  external  appearance, 
and  occupy  the  same  position  in  the  abdomen,  as  the  testicles  in  the 
opposite  sex.  The  descent  of  the  ovaries  also  takes  place,  to  a  great 
extent,  in  the  same  manner  with  the  descent  of  the  testicles.  When, 
in  the  early  part  of  this  descent,  they  have  reached  the  level  of  the 
lo^y■er  edge  of  the  kidneys,  a  cord,  analogous  to  the  gubernaculum, 
may  be  seen  proceeding  from  their  lower  extremity,  crossing  the 
efferent  duct  on  each  side,  and  passing  downward,  to  be  attached 
to  the  subcutaneous  tissues  at  the  situation  of  the  inguinal  ring. 
That  part  of  the  duct  situated  outside  the  crossing  of  this  cord, 
heQomQ'i  afterward  convoluted,  and  is  converted  into  the  Fallopian 
lube;  while  that  part  which  is  inside  the  same  point,  becomes  con- 
verted into  the  uterus.    The  upper  portion  of  the  cord  itself  becomes 


FEMALE  ORGANS  OF  GENERATION.         563 

the  ligament  of  the  ovary;  its  lower  portion,  \\\q  round  ligament  of  the 
xUerus. 

As  the  ovaries  continue  their  descent,  they  pass  below  and  be- 
hind the  Fallopian  tubes,  which  necessarily  perform  at  the  same 
time  a  movement  of  rotation,  from  before  backward  and  from 
above  downward ;  the  whole,  together  with  the  ligaments  of  the 
ovaries  and  the  round  ligaments,  being  enveloped  in  double  folds 
of  peritoneum,  which  enlarge  with  the  growth  of  the  parts  them- 
selves, and  constitute  finally  the  hroad  ligaments  of  the  uterus. 

It  will  be  seen  from  what  has  been  said  above,  that  the  situation 
occupied  by  the  Wolffian  bodies  in  the  female  is  always  the  space 
between  the  ovaries  and  the  Fallopian  tubes;  for  the  Wolffian  bodies 
accompany  the  ovaries  in  their  descent,  just  as,  in  the  male,  they 
accompany  the  testicles.  As  these  bodies  now  become  gradually 
atrophied,  their  glandular  structure  disappears  altogether;  but 
their  bloodvessels,  in  many  instances,  remain  as  a  convoluted  vas- 
cular plexus,  occupying  the  situation  above  mentioned.  The 
Wolffian  bodies  may  therefore  be  said,  in  these  instances,  to  un- 
dergo a  kind  of  vascular  degeneration.  This  peculiar  degeneration 
is  quite  evident  in  the  Wolffian  bodies  of  the  foetal  pig,  some  time 
before  the  organs  have  entirely  lost  their  original  form.  In  the 
cow,  a  collection  of  convoluted  bloodvessels  may  be  seen,  even  in 
the  adult  condition,  near  the  edge  of  the  ovary  and  between  the 
two  folds  of  peritoneum  forming  the  broad  ligament.  These  are 
undoubtedly  vestiges  of  the  Wolffian  bodies,  which  have  under- 
gone the  vascular  degeneration  above  described. 

While  the  above  changes  are  taking  place  in  the  adjacent  organs, 
the  two  lateral  halves  of  the  uterus  fuse  with  each  other  more  and 
more  upon  the  median  line,  and  become  covered  with  an  exces- 
sively developed  layer  of  muscular  fibres.  In  the  lower  animals, 
the  uterus  remains  divided  at  its  upper  portion,  running  (jut  into 
two  long  conical  tubes  or  cornua  (Fig.  165),  presenting  the  form 
known  as  the  uterus  bicornis.  In  the  human  subject,  however,  the 
fusion  of  the  two  lateral  halves  of  the  organ  is  nearly  complete ; 
so  that  the  uterus  presents  externally  a  rounded,  but  somewhat 
flattened  and  triangular  figure  (Fig.  166).  with  the  ligaments  of  the 
ovary  and  the  round  ligaments  passing  off  from  its  superior  angles. 
But,  internally,  the  cavity  of  the  organ  still  presents  a  strongly 
marked  triangular  form,  the  vestige  of  its  original  division. 

Occasionally  the  human  uterus,  even  in  the  adult  condition,  re- 


564        DEVELOPMENT  OF  THE  KIDXEYS,  ETC. 

mains  divided  into  two  lateral  portions  by  a  vertical  septum,  which 
runs  from  the  middle  of  its  fundus  downward  toward  the  os  in- 
ternum. This  septum  may  even  be  accompanied  by  a  partial 
external  division  of  the  organ,  corresponding  with  it  in  direction, 
and  producing  the  malformation  known  as  "  uterus  bicoruis,"  or 
"  double  uterus." 

.  The  OS  internum  and  os  externum  are  produced  by  partial  con- 
strictions of  the  original  generative  passage;  and  the  anatomical 
distinctions  between  the  body  of  the  uterus,  the  cervix  and  the 
vagina  are  produced  by  the  different  development  of  the  mucous 
membrane  and  muscular  tunic  in  its  corresponding  portions. 
During  foetal  life,  however,  the  neck  of  the  uterus  grows  much 
faster  than  its  body ;  so  that,  at  the  period  of  birth,  the  entire  or- 
gan is  very  far  from  presenting  the  form  which  it  exhibits  in  the 
adult  condition.  In  the  human  foetus  at  term,  the  cervix  uteri 
constitutes  nearly  two-thirds  of  the  entire  length  of  the  organ  ; 
while  the  body  forms  but  little  over  one-third.  The  cervix,  at 
this  time,  is  also  much  larger  in  diameter  than  the  body ;  so  that 
the  whole  organ  presents  a  tapering  form  from  below  upward. 
The  arbor  vitse  uterina  of  the  cervix  is  at  birth  very  fully  de- 
veloped, and  the  mucous  membrane  of  the  body  is  also  thrown  into 
three  or  four  folds  which  radiate  upward  from  the  os  internum. 
The  cavity  of  the  cervix  is  filled  with  a  transparent  semi-solid 
mucus. 

The  position  of  the  uterus  at  birth  is  also  different  from  that 
which  it  assumes  in  adult  life ;  nearly  the  entire  length  of  the  organ 
being  above  the  level  of  the  symphysis  pubis,  and  its  inferior  ex- 
tremity passing  below  that  point  only  by  about  a  quarter  of  an 
inch.  It  is  also  slightly  anteflexed  at  the  junction  of  the  body  and 
cervix.  After  birth,  the  uterus,  together  with  its  appendages,  con- 
tinues to  descend ;  until,  at  the  period  of  puberty,  its  fundus  is 
situated  just  below  the  level  of  the  symphysis  pubis. 

The  ovaries  at  birth  are  narrow  and  elongated  in  form.  They 
contain  at  this  time  an  abundance  of  eggs;  each  inclosed  in  a 
Graafian  follicle,  and  averaging  ^\^  of  an  inch  in  diameter.  The 
vitellus,  however,  is  imperfectly  formed  in  most  of  them,  and  in 
some  is  hardly  to  be  distinguished.  The  Graafian  follicle  at  this 
period  envelopes  each  egg  closely,  there  being  nothing  between  its 
internal  surface  and  the  exterior  of  the  egg,  excepting  the  thin 
layer  of  cells  forming  the  "membrana  granulosa."     Inside  this 


FEMALE  ORGANS  OF  GENERATION.         565 

layer  is  to  be  seen  the  germinative  vesicle,  with  the  germinative 
spot,  surrounded  by  a  faintly  granular  vitellus,  more  or  less 
abundant  in  different  parts.  Some  of  the  Graafian  follicles  con- 
taining eggs  are  as  large  as  ^^^  of  an  inch;  others  as  small  as  tij'ss- 
In  the  very  smallest,  the  cells  of  the  membrana  granulosa  appear 
to  fill  entirely  the  cavity  of  the  follicle,  and  no  vitellus  or  germina- 
tive vesicle  is  to  be  seen. 


566        DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


CHAPTER    XVII. 

DEVELOPMENT  OF   THE   CIRCULATORY   APPARATUS. 

There  are  three  distinct  forms  or  phases  of  development  assumed 
by  the  circulatory  system  during  different  periods  of  life.  These 
different  forms  of  the  circulation  are  intimately  connected  with  the 
manner  in  which  nutrition  and  respiration,  or  the  renovation  of  the 
blood,  are  accomplished  at  different  epochs ;  and  they  follow  each 
other  in  the  progress  of  development,  as  different  organs  are  em- 
ployed in  turn  to  accomplish  the  above  functions.  The  first  form 
is  that  of  the  vitelline  circulation,  which  exists  at  a  period  when  the 
vitellus,  or  the  umbilical  vesicle,  is  the  sole  source  of  nutrition  for 
the  foetus.  The  second  is  the  placental  circulation,  which  lasts 
through  the  greater  part  of  foetal  life,  and  is  characterized  by  the 
existence  of  the  placenta;  and  the  third  is  the  complete  or  adult 
circulation,  in  which  the  renovation  and  nutrition  of  the  blood  are 
provided  for  by  the  lungs  and  the  intestinal  canal. 

First,  or  Vitelline  Circulation. — It  has  already  been  shown  in  a 
previous  chapter,  that  when  the  body  of  the  embryo  has  begun  to 
be  formed  in  the  centre  of  the  blastodermic  membrane,  a  number 
of  bloodvessels  shoot  out  from  its  sides,  and  ramify  over  the 
remainder  of  the  vitelline  sac,  forming,  by  their  inosculation,  an 
abundant  vascular  plexus.  The  area  occupied  by  this  plexus  in  the 
blastodermic  membrane  around  the  foetus  is,  as  we  have  seen,  the 
"  area  vasculosa."  In  the  egg  of  the  fowl  (Fig.  233),  the  plexus  is 
limited,  on  its  external  border,  by  a  terminal  vein  or  sinus — the 
"sinus  terminalis";  and  the  blood  of  the  embryo,  after  circulating 
through  the  capillaries  of  the  plexus,  returns  by  several  venous 
branches,  the  two  largest  of  which  enter  the  body  near  its  anterior 
and  posterior  extremities.  The  area  vasculosa  is,  accordingly,  a 
vascular  appendage  to  the  circulatory  apparatus  of  the  embryo, 
spread  out  over  the  surface  of  the  vitellus  for  the  purpose  of  absorb- 
ing from  it  the  nutritious  material  requisite  for  the  growth  of  the 
newly-formed  tissues.     In  the  egg  of  the  fish  (Fig.  234),  the  princi- 


VITELLINE    CIRCULATION. 


567 


pal  vein  is  seen  passing  up  in  front  underneath  the  head ;  while  the 
arteries  emerge  all  along  the  lateral  edges  of  the  body.  The  entire 
vitellus,  in  this  way,  becomes  covered  with  an  abundant  vascular 

Fig.  233. 


Eoo   OF   Fowl  in  process  of  development,  showing  area  .vasculosa,  with  .vitelline  circulation, 
terminal  sinus,  &c. 

network,  connected  with  the  internal  circulation  of  the  foetus  by 
arteries  and  veins. 

Very  soon,  as  the  embryo  and  the  entire  egg  increase  in  size, 
there  are  two  arteries  and  two  veins  which  become 
larger  than  the  others,  and  which  subsequently 
do  the  whole  work  of  conveying  the  blood  of 
the  foetus  to  and  from  the  area  vasculosa.  These 
two  arteries  emerge  from  the  lateral  edges  of 
the  foetus,  on  the  right  and  left  sides ;  while  the 
two  veins  re-enter  at  about  the  same  point,  and 
nearly  parallel  with  them.  These  four  vessels  are 
then  termed  the  omphalo-mesenteric  arteries  and 
veins. 

The  arrangement  of  the  circulatory  apparatus 
in  the  interior  of  the  body  of  the  foetus,  at  this  time,  is  as  follows: 
The  heart  is  situated  on  the  median  line,  just  beneath  the  head  and 
in  front  of  the  oesophagus.  It  receives  at  its  lower  extremity  the 
trunks  of  the  two  omphalo-mesenteric  veins,  and  at  its  upper 
extremity  divides  into  two  vessels,  which,  arching  over  backward, 
attain  the  anterior  surface  of  the  vertebral  column,  and  then  run 
from  above  downward  along  the  spine,  quite  to  the  posterior 
extremity  of  the  foetus.  These  arteries  are  called  the  vertebral 
arteries^  on  account  of  their  course  and,  situation, running  parallel 


EoG  OF  Fish  ( Jar- 
rabacca),  showing  vitel- 
line circulation. 


568        DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


with  the  vertebral  column.  They  give  off,  throughout  their  course, 
many  small  lateral  branches,  which  supply  the  body  of  the  fcetus, 
and  also  two  larger  branches — the  oraphalo-raesenteric  arteries — 
which  pass  out,  as  above  described,  into  the  area  vasculosa.  The 
two  vertebral  arteries  remain  separate  in  the  upper  part  of  the  body, 
but  soon  fuse  with  each  other  a  little  below  the  level  of  the  heart : 
so  that,  below  this  point,  there  remains  afterward  but  one  large 
artery,  the  abdominal  aorta,  running  from  above  downward  along 
the  median  line,  giving  off  the  omphalo-mesenteric  arteries  to  the 
area  vasculosa,  and  supplying  smaller  branches  to  the  body,  the 
walls  of  the  intestine,  and  the  other  organs  of  the  foetus. 

The  above  description  shows  the  origin  and  formation  of  the  first 
or  vitelline  circulation.  A  change,  however,  now  begins  to  take 
place,  by  which  the  vitellus  is  superseded,  as  an  organ  of  nutrition, 
by  the  placenta,  which  takes  its  place;  and  the  second  or  jjlacental 
circulation  becomes  established  in  the  following  manner: — 

Second  Circulation. — After  the  umbilical  vesicle  has  been  formed 
by  the  process  already  described,  a  part  of  the  vitellus  remains 
included  in  it,  while  the  rest  is  retained  in  the  abdomen  and  inclosed 

in  the  intestinal  canal.  As  these 
two  organs  (umbilical  vesicle  and 
intestine)  are  originally  parts  of 
the  same  vitelline  sac,  they  remain 
supplied  by  the  same  vascular 
system,  viz :  the  omphalo-mesen- 
teric vessels.  Those  which  remain 
within  the  abdomen  of  the  foetus 
supply  the  mesentery  and  intes- 
tine ;  but  the  larger  trunks  pass 
outward,  and  ramify  upon  the 
walls  of  the  umbilical  vesicle. 
(Fig.  235.)  At  first,  there  are, 
as   we   have    mentioned    above, 

Diagram    ofYouNoEMBRYOANDiTS 
Vessels,    showing    circulation    of   umbilical     tWO    OmphalO-meSCnteriC    artcriCS 

vesicle,  and  also  that  of  aiiantois,  beginning  to    emerging  from  the  body,  and  two 

be  formed.  .  . 

omphalo-mesenteric  veins  return- 
ing to  it;  but  soon  afterward,  the  two  arteries  are  replaced  by  a 
common  trunk,  while  a  similar  change  takes  place  in  the  two  veins- 
Subsequently,  therefore,  there  remains  but  a  single  artery  and  a 
single  vein,  connecting  the  internal  and  external  portions  of  the 
vitelline  circulation. 


Fig.  235. 


PLACENTAL  CIECULATION 


569 


The  vessels  belonging  to  this  system  are  therefore  called  the 
omphalo-mesenteric  vessels,  because  a  part  of  them  (omphalic  ves- 
sels) pass  outward,  by  the  umbilicus,  or  "  omphalos,"  to  the  umbili- 
cal vesicle,  while  the  remainder  (mesenteric  vessels)  ramify  upon 
the  mesentery  and  the  intestine. 

At  first,  the  circulation  of  the  umbilical  vesicle  is  more  import- 
ant than  that  of  the  intestine ;  and  the  omphalic  artery  and  vein 
appear  accordingly  as  large  trunks,  of  which  the  mesenteric  ves- 
sels are  simply  small  branches.  (Fig.  235.)  Afterward,  however, 
the  intestine  rapidly  enlarges,  while  the  umbilical  vesicle  dimi- 
nishes, and  the  proportions  existing  between  the  two  sets  of  vessels 
are  therefore  reversed.  (Fig.  236.)     The  mesenteric  vessels  then 

Fig.  236. 


Diagram  of  Embryo  and  its  Vessels;  showing  the  second  circulation.  The  pharynx,  oeso- 
phagus, and  intestinal  canal,  have  become  further  developed,  and  the  mesenteric  arteries  have  en- 
larged, while  the  umhilical  vesicle  and  its  branches  are  vei'y  much  reduced  in  size.  The  large  um- 
bilical arteries  are  seen  passing  out  to  the  placenta. 

come  to  be  the  principal  trunks,  while  the  omphalic  vessels  are 
simply  minute  branches,  running  out  along  the  slender  cord  of  the 
umbilical  vesicle,  and  ramifying  in  a  few  scanty  twigs  upon  its 
surface. 

In  the  mean  time,  the  allantois  is  formed  by  a  protrusion  from 
the  lower  extremity  of  the  intestine,  which,  carrying  with  it  two 


570        DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 

arteries  and  two  veins,  passes  out  by  the  anterior  opening  of  the 
body,  and  comes  in  contact  with  the  external  membrane  of  the  egg. 
The  arteries  of  the  allantois,  which  are  termed  the  umbilical  arte- 
ries, are  supplied  by  branches  of  the  abdominal  aorta;  the  umbi- 
lical veins,  on  the  other  hand,  join  the  mesenteric  veins,  and  empty 
with  them  into  the  venous  extremity  of  the  heart.  As  the  umbi- 
lical vesicle  diminishes,  the  allantois  enlarges;  and  the  latter  soon 
becomes  converted,  in  the  human  subject,  into  a  vascular  chorion, 
a  part  of  which  is  devoted  to  the  formation  of  the  placenta.  (Fig. 
236.)  As  the  placenta  soon  becomes  the  only  source  of  nutrition 
for  the  foetus,  its  vessels  are  at  the  same  time  very  much  increased 
in  size,  and  preponderate  over  all  the  other  parts  of  the  circulatory 
system.  During  the  early  periods  of  the  formation  of  the  placenta, 
there  are,  as  we  have  stated  above,  two  umbilical  arteries  and  two 
umbilical  veins.  But  subsequently  one  of  the  veins  disappears,  and 
the  whole  of  the  blood  is  returned  to  the  body  of  the  foetus  by  the 
other,  which  becomes  enlarged  in  proportion.  For  a  long  time 
previous  to  birth,  therefore,  there  are  in  the  umbilical  cord  two 
umbilical  arteries,  and  but  a  single  umbilical  vein. 

Such  is  the  second,  or  placental  circulation.  It  is  exchanged,  at 
the  period  of  birth,  for  the  third  or  adult  circulation,  in  which  the 
blood  which  had  previously  circulated  through  the  placenta,  is 
diverted  to  the  lungs  and  the  intestine.  These  are  the  organs 
upon  which  the  whole  system  afterward  depends  for  the  nourish- 
ment and  renovation  of  the  blood. 

During  the  occurrence  of  the  above  changes,  certain  other  altera- 
tions take  place  in  the  arterial  and  venous  systems,  which  will  now 
require  to  be  described  by  themselves. 

Development  of  the  Arterial  System.— At  an  early  period  of  deve- 
lopment, as  we  have  shown  above,  the  principal  arteries  pass  off 
from  the  anterior  extremity  of  the  heart  in  two  arches,  which  curve 
backward  on  each  side,  from  the  front  of  the  body  toward  the  ver- 
tebral column,  after  which  they  again  become  longitudinal  in  direc- 
tion, and  receive  the  name  of  "vertebral  arteries."  Yery  soon 
these  arches  divide  successively  into  two,  three,  four,  and  five 
secondary  arches,  placed  one  above  the  other,  along  the  sides  of 
the  neck.  (Fig,  237.)  These  are  termed  the  cervical  arches.  In  the 
fish,  these  cervical  arches  remain  permanent,  and  give  off  from  their 
convex  borders  the  branchial  arteries,  in  the  form  of  vascular  tufts, 
to  the  gills  on  each  side  of  the  neck ;  but  in  the  human  subject  and 
the  quadrupeds,  the  branchial  tufts  are  never  developed,  and  the 


DEVELOPMENT  OF  THE  ARTERIAL  SYSTEM. 


571 


cervical  arches,  as  well  as  the  trunks  with  which  they  are  con- 
nected, become  modified  by  the  progress  of  development  in  the 
followin":  manner: — 


Fig.  237. 


Fig.  238. 


Early  condition  of  A  R  T  E  R  I  A  i,  System; 
showing  the  heart  (1),  with  its  two  ascend- 
ing arterial  trunks,  giving  off  on  each  side 
five  cervical  arches,  which  terminate  in  the 
vertebral  arteries  (2,  2).  The  vertebral  arte- 
ries unite  below  the  heart  to  form  the 
aorta  (3). 


Adult  condition  of  Aiitertai.  Sys- 
tem.— 1,1  Carotids.  2, 2.  Vertebrals. 
3,  3.  Right  and  left  subclavians.  4,  4. 
Eight  and  left  superior  intercostals.  5. 
Left  aortic  arch,  which  remains  perma- 
nent. 6.  Eight  aortic  arch,  which  dis- 
appears. 


The  two  ascending  arterial  trunks  on  the  anterior  part  of  the 
neck,  from  which  the  cervical  arches  are  given  oft",  become  con- 
verted into  the  carotids.  (Fig  288,  i,  i.)  The  fifth,  or  uppermost 
cervical  arch,  remains  at  the  base  of  the  brain  as  the  inosculation, 
through  the  circle  of  Willis,  between  the  internal  carotids  and  the 
basilar  artery,  which  is  produced  by  the  union  of  the  two  verte- 
brals. The  next,  or  fourth  cervical  arch,  may  be  recognized  in  an 
inosculation  which  is  said  to  be  very  constant  between  the  superior 
thyroid  arteries,  branches  of  the  carotids,  and  the  inferior  thyroids, 
which  come  from  the  subclavians  at  nearly  the  same  point  from 
which  the  vertebrals  are  given  off".  The  next,  or  third  cervical  arch 
remains  on  each  side,  as  the  subclavian  artery  (3,  3).  This  vessel, 
though  at  first  a  mere  branch  of  communication  between  the  caro- 
tid and  the  vertebral,  has  now  increased  in  size  to  such  an  extent, 
that  it  has  become  the  principal  trunk,  from  which  the  vertebral 


572        DEVELOPMENT    OF    THE    CIECULATORY    APPARATUS. 

itself  is  given  off  as  a  small  branch.  Immediately  below  this  point 
of  intersection,  also,  the  vertebral  artery  diminishes  very  much  in 
its  relative  size,  loses  its  connection  with  the  abdominal  aorta,  and 
supplies  only  the  first  two  intercostal  spaces,  under  the  name  of  the 
superior  intercostal  artery  (4,  4).  The  second  cervical  arch  becomes 
altered  in  a  very  different  manner  on  the  two  opposite  sides.  On 
the  left  side,  it  becomes  enormously  enlarged,  so  as  to  give  off,  as 
secondary  branches,  all  the  other  arterial  trunks  which  have  been 
described,  and  is  converted  in  this  manner  into  the  arch  of  the 
aorta  (5).  On  the  right  side,  however,  the  corresponding  arch  (e), 
becomes  smaller  and  smaller,  and  at  last  altogether  disappears;  so 
that,  finally,  we  have  only  a  single  aortic  arch,  projecting  to  the 
left  of  the  median  line,  and  continuous  with  the  thoracic  and  abdo- 
minal aorta. 

The  first  cervical  arch  remains  during  fcetal  life  upon  the  right 
side,  as  the  "  ductus  arteriosus,"  presently  to  be  described.  In  the 
adult  condition,  however,  it  has  disappeared  equally  upon  the  right 
and  left  sides.  In  this  way  the  permanent  condition  of  the  arterial 
circulation  is  gradually  established  in  the  upper  part  of  the  body. 

Corresponding  changes  take  place,  however,  during  the  same 
time,  in  the  lower  part  of  the  body.  Here  the  abdominal  aorta 
runs  undivided,  upon  the  median  line,  quite  to  the  end  of  the 
spinal  column;  giving  off  on  each  side  successive  lateral  branches, 
which  supply  the  intestine  and  the  parietes  of  the  body.  When 
the  allantois  begins  to  be  developed,  two  of  these  lateral  branches 
accompany  it,  and  become  consequently  the  umbilical  arteries. 
These  two  vessels  increase  so  rapidly  in  size,  that  they  soon  appear 
as  divisions  of  the  aortic  trunk  ;  while  the  original  continuation  of 
this  trunk,  running  to  the  end  of  the  spinal  column,  appears  only 
as  a  small  branch  given  off'  at  the  point  of  bifurcation.  When  the 
lower  limbs  begin  to  be  developed,  they  are  supplied  by  two  small 
branches,  given  off"  from  the  umbilical  arteries  near  their  origin. 

Up  to  this  time  the  pelvis  and  posterior  extremities  are  but 
slightly  developed.  Subsequently,  however,  they  grow  more 
rapidly,  in  proportion  to  the  rest  of  the  body,  and  the  arteries 
which  supply  them  increase  in  a  corresponding  manner.  That 
portion  of  the  umbilical  arteries,  lying  between  the  bifurcation  of 
the  aorta  and  the  origin  of  the  branches  going  to  the  lower  ex- 
tremities, becomes  the  common  iliacs,  which  in  their  turn  afterward 
divide  into  the  umbilical  arteries  proper,  and  the  femorals.  Sub- 
sequently,  by   the   continued    growth    of  the   pelvis   and   lower 


DEVELOPMENT    OF    THE    VENOUS    SYSTEM. 


573 


extremities,  the  relative  size  of  their  vessels  is  still  further  in- 
creased ;  and  at  last  the  arterial  system  in  this  part  of  the  body 
assumes  the  arrangement  which  belongs  to  the  latter  periods  of 
gestation.  The  aorta  divides,  as  before,  into  the  two  common  iliacs. 
These  also  divide  into  the  external  iliacs,  supplying  the  lower  ex- 
tremities, and  the  internal  iliacs,  supplying  the  pelvis;  and  this 
division  is  so  placed  that  the  umbilical  or  hypogastric  arteries  arise 
from  the  internal  iliacs,  of  which  they  now  appear  to  be  secondary 
branches. 

After  the  birth  of  the  foetus  and  the  separation  of  the  placenta, 
the  hypogastric  arteries  become  partially  atrophied,  and  are  con- 
verted, in  the  adult  condition,  into  solid,  rounded  cords,  running 
upward  toward  the  umbilicus.  Their  lower  portion,  however, 
remains  pervious,  and  gives  off  arteries  supplying  the  urinary 
bladder.  The  obliterated  hypogastric  arteries,  therefore,  the  rem- 
nants of  the  original  umbilical  or  allantoic  arteries,  run  upward 
from  the  internal  iliacs  along  the  sides  of  the  urinary  bladder,  which 
is  the  remnant  of  the  original  allantois  itself.  The  terminal  con- 
tinuation of  the  original  abdominal  aorta,  is  the  arteria  sacra  media, 
which,  in  the  adult,  runs  downward  on  the  anterior  surface  of  the 
sacrum,  supplying  branches  to  the  rectum  and  the  anterior  sacral 
nerves. 

Development  of  the  Venous  System. — According 
to  the  observations  of  M.  Coste,  the  venous  system 
at  first  presents  the  same  simplicity  and  symmetry 
with  the  arterial.  The  principal  veins  of  the 
body  consist  of  two  long  venous  trunks,  the  ver- 
iehral  veins  (Fig.  289),  which  run  along  the  sides 
of  the  spinal  column,  parallel  with  the  vertebral 
arteries.  They  receive  in  succession  all  the  inter- 
costal veins,  and  empty  into  the  heart  by  two 
lateral  trunks  of  equal  size,  the  canals  of  Cuvier. 
When  the  inferior  extremities  become  developed, 
their  two  veins,  returning  from  below,  join  the 
vertebral  veins  near  the  posterior  portion  of  the 
body ;  and,  crossing  them,  afterward  unite  with 
each  other,  thus  constituting  another  vein  of  new 
formation  (Fig.  240,  a),  which  runs  upward  a  little  EariyconaitionofVK- 
to  the  right  of  the  median  line,  and  empties  by    ';>-o^s  s^s^m;  show- 

^  '  i-  tJ       mg  the  vertebral  veins 

itself  into  the  lower  extremity  of  the  heart.     The    emptying  into  the  heart 

.  ^  ^  -I  r        1   •    T      J.^  ■  n     ^7  two  lateral  trunks, 

two  branches,  by  means  o±  which  the  veins  of   the  "eauaisof  cuvier." 


Fig   239. 


574       DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


Fig.  240. 


Venous  System  far- 
ther advanced,  showing 
formation  of  iliac  and  sub- 
clavian veins. — a.  Vein  of 
new  formation,  which  be- 
comes the  inferior  vena 
cava.  ft.  Transverse  branch 
of  new  formation,  which 
afterward  becomes  the  left 
vena  innominata. 

Fig.  241. 


Further  development  of 
the  Venous  System  — 
The  vertebral  veins  are 
much  diminished  in  size, 
and  the  canal  of  Cuvier,  on 
the  left  side,  is  gradually- 
disappearing,  c.  Trans- 
verse branch  of  new  forma- 
tion, which  is  to  become 
the  vena  azygos  minor. 


the  lower  extremities  thus  unite,  become  after- 
ward, by  enlargement,  the  common  iliac  veins; 
while  the  single  trunk  (a)  resulting  from  their 
union  becomes  the  vena  cava  inferior.  Subse- 
quently, the  vena  cava  inferior  becomes  very 
much  larger  than  the  vertebral  veins ;  and  its 
two  branches  of  bifurcation  are  afterward  re- 
presented by  the  two  iliacs. 

Above  the  level  of  the  heart,  the  vertebral 
and  intercostal  veins  retain  their  relative  size 
until  the  development  of  the  superior  extremi- 
ties has  commenced.  Then  two  of  the  inter- 
costal veins  increase  in  diameter  (Fig.  240),  and 
become  converted  into  the  right  and  left  sub- 
clavians ;  while  those  portions  of  the  vertebral 
veins  situated  above  the  subclavians  become 
the  right  and  left  jugulars.  Just  below  the 
junction  of  the  jugulars  with  the  subclavians, 
a  small  branch  of  communication  now  appears 
between  the  two  vertebrals  (Fig.  240,  6),  pass- 
ing over  from  left  to  right,  and  emptying  into 
the  right  vertebral  vein  a  little  above  the  level 
of  the  heart ;  so  that  a  part  of  the  blood  coming 
from  the  left  side  of  the  head,  and  the  left  upper 
extremity,  still  passes  down  the  left  vertebral 
vein  to  the  heart  upon  its  own  side,  while  a  part 
crosses  over  by  the  communicating  branch  (6), 
and  is  finally  conveyed  to  the  heart  by  the 
right  descending  vertebral.  Soon  afterward,  this 
branch  of  communication  enlarges  so  rapidly 
that  it  preponderates  altogether  over  the  left 
superior  vertebral  vein,  from  which  it  ori- 
ginated (Fig.  241),  and,  serving  then  to  convey 
all  the  blood  coming  from  the  left  side  of  the 
head  and  left  upper  extremity  over  to  the  right 
side  above  the  heart,  it  becomes  the  left  vena 
innominata. 

On  the  left  side,  that  portion  of  the  superior 
vertebral  vein,  which  is  below  the  subclavian, 
remains  as  a  small  branch  of  the  vena  innomi 
nata,  receiving  the  six  or  seven  upper  intercostal 


DEVELOPMENT    OF    THE    VENOUS    SYSTEM. 


575 


Fig.  242. 


veins;  while  on  the  right  side  it  becomes  excessively  enlarged, 
receiving  the  blood  of  both  jugulars  and  both  subclavians,  and  is 
converted  into  the  vena  cava  superior. 

The  left  canal  of  Cuvier,  by  which  the  left  vertebral  vein  at  first 
communicates  with  the  heart,  subsequently  becomes  atrophied  and 
disappears;  while  on  the  right  side  it  becomes  excessively  enlarged, 
and  forms  the  lower  extremity  of  the  vena  cava  superior. 

The  superior  and  inferior  venae  cavae,  accordingly,  do  not  cor- 
respond with  each  other  so  far  as  regards  their 
mode  of  origin,  and  are  not  to  be  regarded  as 
analogous  veins.  For  the  superior  vena  cava 
is  one  of  the  original  vertebral  veins ;  while 
the  inferior  vena  cava  is  a  totally  distinct  vein, 
of  new  formation,  resulting  from  the  union  of 
the  two  lateral  trunks  coming  from  the  infe- 
rior extremities. 

The  remainder  of  the  vertebral  veins  finally 
assume  the  condition  shown  in  Fig.  242,  which 
is  the  complete  or  adult  form  of  the  venous 
circulation.  At  the  lower  part  of  the  abdomen, 
the  vertebral  veins  send  inward  small  trans- 
verse branches,  which  communicate  with  the 
vena  cava  inferior,  between  the  points  at  which 
they  receive  the  intercostal  veins.  These 
branches  of  communication,  by  increasing  in 
size,  become  the  lumbar  veins  (7),  which,  in  the 
adult  condition,  communicate  with  each  other 
by  arched  branches,  a  short  distance  to  the  side 
of  the  vena  cava.  Above  the  level  of  the 
lumbar  arches,  the  vertebral  veins  retain  their 

.5.  Vena  cava  inferior.     6,  6. 

original  direction.    .That  upon  the  right  side    niac  veins  v.  Lumbar  veins, 
still  receives  all  the  right  intercostal  veins,  and    ';  ^'''"^  ■''''^''  ""'"'Z'  J' 

o  '  Vena  azygos  minor.     10.  su- 

becomes  the  vena  azyjos  major  (s).  It  also  perior  intercostal  vein. 
receives  a  small  branch  of  communication  from 
its  fellow  of  the  left  side  (Fig.  24.1,  c),  and  this  branch  soon  enlarges 
to  such  an  extent  as  to  bring  over  to  the  vena  azygos  major  all  the 
blood  of  the  five  or  six  lower  intercostal  veins  of  the  left  side, 
becoming,  in  this  way,  the  vena  azygos  minor  {9).  The  six  or  seven 
upper  intercostal  veins  on  the  left  side  still  empty,  as  before,  into 
their  own  vertebral  vein  (10),  which,  joining  the  left  vena  innomi- 
nata  above,  is  known  as  the  superior  intercostal  vein.    The  left  canal 


Adult  condition  of  Ve- 
xors  System.  —  1.  Riglit 
auricle  of  heart.  2.  Vena 
cava  superior.  3,  3.  Jugular 
veins.  4,1:.  Subclavian  veins. 


576        DEVELOPMENT    OF    THE    CIECULATORY    APPARATUS. 

of  Cuvier  lias  by  this  time  entirely  disappeared;  so  that  all  the 
venous  blood  now  enters  the  heart  by  the  superior  or  the  inferior 
vena  cava.  But  the  original  vertebral  veins  are  still  continuous 
throughout,  though  very  much  diminished  in  size  at  certain  points; 
since  both  the  greater  and  lesser  azygous  veins  inosculate  below 
with  the  superior  lumbar  veins,  and  the  superior  intercostal  vein 
also  inosculates  below  with  the  lesser  azygous,  just  before  it  passes 
over  to  the  right  side. 

There  are  still  two  parts  of  the  circulatory  apparatus,  the  deve- 
lopment of  which  presents  peculiarities  sufficiently  important  to 
be  described  by  themselves.     These  are,  first,  the  liver  and  the 
ductus  venosus,  and  secondly,  the  heart,  with  the  ductus  arteriosus. 
Development  of  the  Hepatic  Circulation  and  the  Ductvs  Venosus. — 
The  liver  appears  at  a  very  early  period  in  the  upper  part  of  the 
abdomen,  as  a  mass  of  glandular  and  vascular  tissue,  which  is  deve- 
loped around  the  upper  portion  of  the  om- 
Fig.  243.  phalo-rnesenteric  vein,  just  below  its  termi- 

nation in  the  heart.  (Fig.  243.)  As  soon  as 
the  organ  has  attained  a  considerable  size, 
the  omphalo-mesenteric  vein  (i)  breaks  up  in 
its  interior  into  a  capillary  plexus,  the  vessels 
of  which  unite  again  into  venous  trunks,  and 
so  convey  the  blood  finally  to  the  heart. 
The  omphalo-mesenteric  vein  below  the  liver 
Early  form  of  Hepatic  then  hecomes  the portal veiu ;  while  above  tiie 
ciKccLATioN.  1  ompha-      ^.         ^^^  between  that  organ  and  the  heart, 

lo  mesenteric  vein.     2.  Hepa-  '  o  ' 

tic  vein.  3.  Heart.  Tiiedotted      [{,  rcccivcs  the  uamc  of  the  hcpatic  Vein  (2). 

line  shows   the   situation   of        „,       ,.  t        i       •        .    .1   •     .  •  v     i 

the  fnture  umbilical  vein.  The  hvcr,  accordiugly,  is  at  this  time  supplied 
with  blood  entirely  by  the  portal  vein,  com- 
ing from  the  umbilical  vesicle  and  the  intestine;  and  all  the  blood 
derived  from  this  source  must  pass  through  the  hepatic  circulation 
before  reaching  the  venous  extremity  of  the  heart. 

But  soon  afterward  the  allantois  makes  its  appearance,  and  be- 
comes rapidly  developed  into  the  placenta ;  and  the  umbilical  vein 
comino-  from  it  joins  the  omphalo-mesenteric  vein  in  the  substance 
of  the  liver,  and  takes  part  in  the  formation  of  the  hepatic  capillary 
plexus.  As  the  umbilical  vesicle,  however,  becomes  atrophied,  and 
the  intestine  also  remains  inactive,  while  the  placenta  increases  in 
size  and  in  functional  importance,  a  time  soon  arrives  when  the 
liver  receives  more  blood  by  the  umbilical  vein  than  by  the  portal 
vein.  (Fig.  244.)     The  umbilical  vein  then  passes  into  the  liver  at 


DEVELOPMENT    OF    THE    HEPATIC    CIRCULATION. 


577 


Hepatic  CiRCULATioif 
further  advanced. — 1.  Portal  vein. 
2.  Umbilical  vein.  3.  Hepatic 
vein. 


the  longitudinal  fissure,  and  supplies  the  left  lobe  entirely  with  its 
own  branches.  To  the  right  it  sends  off  a  large  branch  of  com- 
munication, which  opens  into  the  portal  vein,  and  partially  supplies 
the  right  lobe  witb  umbilical  blood.  The  liver  is  thus  supplied 
with  blood  from  two  different  sources,  the 
most  abundant  of  which  is  the  umbilical 
vein  ;  and  all  the  blood  entering  the  liver 
circulates,  as  before,  through  its  capillary 
vessels. 

But  we  have  already  seen  that  the  liver 
is  much  larger  in  proportion  to  the  entire 
body  at  an  early  period  of  foetal  life  than 
in  the  later  months.  In  the  foetal  pig, 
when  very  young,  it  amounts  to  nearly 
twelve  per  cent,  of  the  weight  of  the  whole 
body;  but  before  birth  it  diminishes  to 
seven,  six,  and  even  three  or  four  per  cent. 

For  some  time,  therefore,  previous  to  birth,  there  is  mucb  more 
blood  returned  from  the  placenta  than  is  required  for  the  capillary 
circulation  of  the  liver.  Accordingly,  a  vascular  duct  or  canal  is 
formed  in  its  interior,  by  which  a  portion  of  the  placental  blood  is 
carried  directly  through  the  organ, 
and  conveyed  to  the  heart  Avithout 
having  passed  through  the  hepatic 
capillaries.  This  duct  is  called  the 
Ductus  venosus. 

The  ductus  venosus  is  formed  by  a 
gradual  dilatation  of  one  of  the  he- 
patic capillaries  at  (s)  (Fig.  245), 
which,  enlarging  excessively,  be- 
comes at  last  converted  into  a  wide 
canal,  or  branch  of  communication, 
passing  directly  from  the  umbilical 
vein  below  to  tlie  hepatic  vein  above. 
The  circulation  through  the  liver, 
thus  established,  is  as  follows :  A 
certain  quantity  of  venous  blood  still 
enters  through  the  portal  vein  (i), 
and  circulates  in  a  part  of  the  capil- 
lary system  of  the  right  lobe.  The  umbilical  vein  (2),  bringing  a 
much  larger  quantity  of  blood,  enters  the  liver  also,  a  little  to  the 
37 


Hepatic  CiRCDLATioN  during  lat- 
ter part  of  foetal  life. — 1.  Portal  vein.  2. 
Umbilical  vein.  3.  Left  branch  of  umbili- 
cal vein.  4.  Right  branch  of  umbilical 
vein.  5.  Ductus  venosus.  6.  Hepatic 
vein. 


578        DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


left,  and  the  blood  which  it  contains  divides  into  three  principal 
streams.  One  of  them  passes  through  the  left  branch  (3)  into  the 
capillaries  of  the  left  lobe ;  another  turns  oft'  through  the  right 
branch  (4),  and,  joining  the  blood  of  the  portal  vein,  circulates 
through  the  capillaries  of  the  right  lobe ;  while  the  third  passes 
directly  onward  through  the  venous  duet  (5),  and  reaches  the  he- 
patic vein  without  having  passed  through  any  part  of  the  capillary 
plexus. 

This  condition  of  the  hepatic  circulation  continues  until  birth. 
At  that  time,  two  important  changes  tai^e  place.  First,  the  pla- 
cental circulation  is  altogether  cut  off;  and  secondly,  a  much  larger 
quantity  of  blood  than  before  begins  to  circulate  through  the  lungs 
and  the  intestine.  The  superabundance  of  blood,  previously  coming 
from  the  placenta,  is  now  diverted  into  the  lungs ;  while  the  intes- 
tinal canal,  entering  upon  the  active  performance  of  its  functions, 
becomes  the  sole  source  of  supply  for  the  hepatic  venous  blood. 
The  following  changes,  therefore,  take  place  at  birth  in  the  vessels 
of  the  liver.  (Fig.  246.)  First,  the  umbilical  vein  shrivels  and 
becomes  converted  into  a  solid  rounded  cord  (2).  This  cord  may 
be  seen,  in  the  adult  condition,  running  from  the  internal  surface  of 
the  abdominal  walls,  at  the  umbilicus,  to  the  longitudinal  fissure  of 

the  liver.  It  is  then  known  under  the 
name  of  the  round  ligament.  Secondly, 
the  ductus  venosus  also  becomes  ob- 
literated, and  converted  into  a  fibrous 
cord.  Thirdly,  the  blood  entering  the 
liver  by  the  portal  vein  ( i ),  passes  off 
by  its  right  branch,  as  before,  to  the 
right  lobe.  But  in  the  branch  (4),  the 
course  of  the  blood  is  reversed.  This 
was  formerly  the  right  branch  of  the 
umbilical  vein,  its  blood  passing  in  a 
direction  from  left  to  right.  It  now 
becomes  the  left  branch  of  the  portal 
vein ;  and  its  blood  passes  from  right 
to  left,  to  be  distributed  to  the  capil- 
laries of  the  left  lobe. 

According  to  Dr.  Guy,  the  umbili- 
cal vein   is  completely  closed  at  the 
end  of  the  fifth  day  after  birth. 
Development  of  the  Hearty  and  the  Ductus  Arteriosus. — When   the 


Yxs..  246. 


Adult  form  of  Hepatic  Ciuccla- 
TION. — 1.  Portal  veiu.  2.  Obliterated 
umbilical  vein,  forming  the  round  liga 
ment ;  the  continuation  of  the  dotted 
lines  through  the  liver  shoves  the  situa- 
tion of  the  obliterated  ductus  venosus. 
3.  Hepatic  vein.  4.  Left  branch  of  portal 
vein. 


DEVELOPMENT  OF  THE  HEART. 


579 


embryonic  circulation  is  first  established,  the  heart  is  a  simple  tubu- 
lar sac  (Fig.  247),  receiving  the  veins  at  its  lower  extremity,  and 
giving  off'  the  arterial  trunks  at  its  upper  extremity.  By  the  pro- 
gress of  its  growth,  it  soon  becomes  twisted  upon  itself;  so  that  the 
entrance  of  the  veins,  and  the  exit  of  the  arteries,  come  to  be  placed 
more  nearly  upon  the  same  horizontal  level  (Fig.  248) ;  but  the 
entrance  of  the  veins  (i)  is  behind  and  a  little  below,  while  the  exit 
of  the  arteries  (2)  is  in  front  and  a  little  above.  The  heart  is,  at 
this  time,  a  simple  twisted  tube;  and  the  blood  passes  through  it 
in  a  single  continuous  stream,  turning  upon  itself  at  the  point  of 
curvature,  and  passing  directly  out  by  the  arterial  orifice. 


Fig.  247. 

2 


Earliest  form  of  F(etal 
Heart. — 1.  venous  ex- 
tremity. 2.  Arterial  ex- 
tremity. 


Fis.  248. 


FffiTAL  Heart,  twi.sted 
upon  itself. — 1.  Venous  ex- 
tremity. 2.  Arterial  ex- 
tremitv. 


FfKfAL  Heart,  divided 
into  right  and  left  cavities. — 
1.  Venous  extremity.  2. 
Arterial  extremity.  3,  3. 
Pulmonary  branches. 


Soon  afterward,  this  single  cardiac  tube  is  divided  into  two  paral- 
lel tubes,  right  and  left,  by  a  longitudinal  partition,  which  grows 
from  the  inner  surface  of  its  walls  and  follows  the  twisted  course 
of  the  organ  itself.  (Fig.  249.)  This  partition,  which  is  indicated 
in  the  figure  by  a  dotted,  line,  extends  a  short  distance  into  the 
commencement  of  the  primitive  arterial  trunk,  dividing  it  into  two 
lateral  halves,  one  of  which  is  in  communication  with  the  right  side 
of  the  heart,  the  other  with  the  left. 

About  the  same  time,  the  pulmonary  branches  (3,3)  are  given 
off"  from  each  side  of  the  arterial  trunk  near  its  origin  ;  and  the 
longitudinal  partition,  above  spoken  of,  is  so  placed  that  both  these 
branches  fall  upon  one  side  of  it,  and  are  both,  consequently,  given 
off'  from  that  division  of  the  artery  which  is  connected  with  the  right 
side  of  the  heart. 

Very  soon  a  superficial  line  of  demarcation,  or  furrow,  shows 
itself  upon  the  external  surface  of  the  heart,  corresponding  in  situa- 
tion with  the  internal  septum ;  while  at  the  root  of  the  arterial 
trunk,  this  furrow  becomes  much  deeper,  and  finally  the  two  lateral 
portions  of  the  vessel  are  separated  from  each  other  altogether,  in 


580       DEVELOPMENT    OF    THE    CIKCULATORY    APPARATUS. 


F(ETAL  Heart  still  far- 
ther developed. — 1.  Aorta. 
2.  Pulmonary  artery.  3,  3. 
Pulmonary  branches.  4. 
Ductus  arteriosus. 


Fig.  250.  the   immediate   neighborhood   of    the    heart, 

joining  again,  however,  a  short  distance  beyond 
the  origin  of  the  pulmonary  branches.  (Fig. 
250.)  It  then  becomes  evident  that  the  left 
lateral  division  of  the  arterial  trunk  is  the 
commencement  of  the  aorta  (i);  while  its  right 
lateral  division  is  the  trunk  of  the  pulmonary 
artery  (2),  giving  off  the  right  and  left  pulmo- 
nary branches  (3,  3),  at  a  short  distance  from 
its  origin.  That  portion  of  the  pulmonary 
trunk  (4)  which  is  beyond  the  origin  of  the 
pulmonary  branches,  and  which  communicates  freely  with  the 
aorta,  is  the  Ductus  arteriosus. 

The  ductus  arteriosus  is  at  first  as  large  as  the  pulmonary  trunk 
itself;  and  nearly  the  whole  of  the  blood,  coming  from  the  right 
ventricle,  passes  directly  onward  through  the  arterial  duct,  and 
enters  the  aorta  without  going  to  the  lungs.  But  as  the  lungs 
gradually  become  developed,  they  require  a  larger  quantity  of 
blood  for  their  nutrition,  and  the  pulmonary  branches  increase  in 
proportion  to  the  pulmonary  trunk  and  the  ductus  arteriosus.  At 
the  termination  of  foetal  life,  in  the  human  subject,  the  ductus 
arteriosus  is  about  as  large  as  either  one  of  the  pulmonary 
branches;  and  a  very  considerable  portion  of  the  blood,  therefore, 
eoming  from  the  right  ventricle  still  passes  onward  to  the  aorta 
without  being  distributed  to  the  lungs. 

But  at  the  period  of  birth,  the  lungs  enter  upon  the  active  per- 
formance of  the  function  of  respiration, 
and  immediately  require  a  much  larger 
supply  of  blood.  The  right  and  left 
pulmonary  branches  then  enlarge,  so 
as  to  become  the  two  principal  divis- 
ions of  the  pulmonary  trunk.  (Fig.  251.) 
The  ductus  arteriosus  at  the  same  time 
becomes  contracted  and  shrivelled  to  such 
an  extent  that  its  cavity  is  obliterated ; 
and  it  is  finally  converted  into  an  im- 
heabt  of  Infant,  showing     pcrvious,  rouudcd  cord,  wliich  remains 

disappearance  of  arterial  duct  after       yxn\i\  adult    life,  rUUniug    frOm  the    poiut 
birth.— 1.  Aorta.     2.  Pulmonary  ar-  p  •  r-      i  i 

tery.   3, 3.  Pulmonary  branches.  4.     of  bifurcatiou  of  the  pulmouary  artery 

Ductus  arteriosus   becoming  oblite-       ^^    ^^^    ^^^j^^    gj^^,   ^f    ^^iQ     arch     of    the 
rated. 


Fig.  2^1. 


DEVELOPMENT  OF  THE  HEART,  581 

aorta.  The  obliteration  of  the  arterial  duct  is  complete,  at  latest, 
by  the  tenth  week  after  birth.  (Gruy.) 

The  two  auricles  are  separated  from  the  two  ventricles  by  hori- 
zontal septa  which  grow  from  the  internal  surface  of  the  cardiac 
walls ;  but  these  septa  remaining  incomplete,  the  auriculo-ventricu- 
lar  orifices  continue  pervious,  and  allow  the  free  passage  of  the 
blood  from  the  auricles  to  the  ventricles. 

The  interventricular  septum,  or  that  which  separates  the  two 
ventricles  from  each  other,  is  completed  at  a  very  early  date ;  but 
the  interauricular  septum,  or  that  which  is  situated  between  the 
two  auricles,  remains  incomplete  for  a  long  time,  being  perforated 
by  an  oval-shaped  opening,  the  foram£n  ovale,  allowing,  at  this 
situation,  a  free  passage  from  the  right  to  the  left  side  of  the  heart. 
The  existence  of  the  foramen  ovale  and  of  the  ductus  arteriosus 
gives  rise  to  a  peculiar  crossing  of  the  streams  of  blood  in  passing 
through  the  heart,  which  is  characteristic  of  foetal  life,  and  which 
may  be  described  as  follows  : — 

It  will  be  found  upon  examination  that  the  two  venae  cavae, 
superior  and  inferior,  do  not  open  into  the  auricular  sac  on  the 
same  plane  or  in  the  same  direction ;  for  while  the  superior  vena 
cava  is  situated  anteriorly,  and  is  directed  downward  and  forward, 
the  inferior  is  situated  quite  posteriorly,  and  passes  into  the  auricle 
in  a  direction  from  right  to  left,  and  nearly  transverse  to  the  axis 
of  the  heart.  A  nearly  vertical  curtain  or  valve  at  the  same  time 
hangs  downward  behind  the  orifice  of  the  superior  vena  cava  and 
in  front  of  the  orifice  of  the  inferior.  This  curtain  is  formed  by 
the  lower  edge  of  the  septum  of  the  auricles,  which,  as  we  have 
before  stated,  is  incomplete  at  this  age,  and  which  terminates 
inferiorly  and  toward  the  right  in  a  crescentic  border,  leaving  at 
that  part  an  oval  opening,  the  foramen  ovale.  The  stream  of  blood, 
coming  from  the  superior  vena  cava,  falls  accordingly  in  front  of 
this  curtain,  and  passes  directly  downward,  through  the  auriculo- 
ventricular  orifice,  into  the  right  ventricle.  But  the  inferior  vena 
cava,  being  situated  farther  back  and  directed  transversely,  opens, 
properly  speaking,  not  into  the  right  auricle,  but  into  the  left ;  for 
its  stream  of  blood,  falling  behind  the  curtain  above  mentioned, 
passes  across  through  the  foramen  ovale  directly  into  the  cavity  of 
the  left  auricle.  This  direction  of  the  current  of  blood,  coming 
from  the  inferior  vena  cava,  is  further  secured  by  a  peculiar  mem- 
branous valve,  which  exists  at  this  period,  termed  the  Eustachian 


582 


DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


valve.  This  valve,  which  is  very  thin  and  transparent  (Fig.  252,/), 
is  attached  to  the  anterior  border  of  the  orifice  of  the  inferior  vena 
cava,  and  terminates  by  a  crescentic  edge,  directed  toward  the  left ; 

the  valve,  in  this  way,  standing 
Fig.  252.  as  an  incomplete  membranous 

partition  between  the  cavity  of 
the  inferior  vena  cava  and  that 
of  the  right  auricle.  A  bougie, 
accordingly,  placed  in  the  in- 
ferior vena  cava,  as  shown  in 
Fig.  252,  lies  naturally  quite 
behind  the  Eustachian  valve, 
and  passes  directly  through 
the  foramen  ovale  into  the  left 
auricle. 

The  two  streams  of  blood, 
therefore,  coming  from  the  su- 
perior and  inferior  venae  cavse, 
cross  each  other  upon  entering 
the  heart.   This  crossing  of  the 
streams  does  not   take   place, 
however,   as    it   is   sometimes 
described,  in  the  cavity  of  the 
right  auricle;  but,  owing  to  the 
peculiar  position  and  direction 
of  the  two  veins  at  this  period, 
witb  regard  to  the  septum  of 
the  auricles,  the  stream  coming  from  the  superior  vena  cava  enters 
the  right  auricle  exclusively,  while  that  from  the  inferior  passes 
almost  directly  into  the  left  auricle. 

It  will  also  be  seen,  by  examining  the  positions  of  the  aorta,  pul- 
monary artery,  and  ductus  arteriosus,  at  this  time,  that  the  arteria 
innominata,  together  with  the  left  carotid  and  left  subclavian,  are 
given  off  from  the  arch  of  the  aorta,  before  its  junction  with  the 
ductus  arteriosus,  and  this  arrangement  causes  the  blood  of  the  two 
venae  cavse,  not  only  to  enter  the  heart  in  different  directions,  but 
also  to  be  distributed,  after  leaving  the  ventricles,  to  different  parts 
of  the  body.  (Fig.  253  )  For  the  blood  of  the  superior  vena  cava 
passes  through  the  right  auricle  downward  into  the  right  ventricle, 
thence  through  the  pulmonary  artery  and  ductus  arteriosus,  into 
the  thoracic  aorta,  while  the  blood  of  the  inferior  vena  cava,  enter- 


Heart  of  Human  Fcetus,  attlie  end  of  the 
sixth  month  ;  from  a  specimen  in  tlie  author's  pos- 
session.— a.  Inferior  vena  cava.  h.  Superior  vena 
cava.  c.  Cavity  of  right  auricle,  laid  open  from 
the  front  d.  Appendix  auricularis.  e.  Cavity  of 
right  ventricle,  also  laid  open.  /.  Eustachian  valve. 
The  bougie,  which  is  placed  in  the  inferior  vena 
cava,,  can  be  seen  passing  behind  the  Eustachian 
valve,  just  below  the  point  indicated  by  f,  then 
crossing  behind  the  cavity  of  the  right  auricle,  and 
passing  through  the  foramen  ovale,  to  the  left  side 
of  the  heart. 


DEVELOPMENT    OF    THE    HEART. 


583 


Fisr.  253. 


ing  the  left  auricle,  passes  into  the  left  ventricle,  thence  into  the  arch 
of  the  aorta,  and  is  distributed  to  the  head  and  upper  extremities, 
before  reaching  the  situation  of  the  arterial  duct.  The  two  streams, 
therefore,  in  passing  through  the  heart,  cross  each  other  both  behind 
and  in  front.  The  venous  blood,  returning  from  the  head  and 
upper  extremities  by  the  superior 
vena  cava,  passes  through  the  abdo- 
minal aorta  and  the  umbilical  arte- 
ries, to  the  lower  part  of  the  body, 
and  to  the  placenta;  while  that  re- 
turning from  the  placenta,  by  the 
inferior  vena  cava,  is  distributed  to 
the  head  and  upper  extremities, 
through  the  vessels  given  off  from 
the  arch  of  the  aorta. 

This  division  of  the  streams  of 
blood,  during  a  certain  period  of 
foetal  life,  is  so  complete  that  Dr. 
John  Reid,^  on  injecting  the  infe 
rior  vena  cava  with  red,  and  the 
superior  with  yellow,  in  a  seven 
months'  human  foetus,  found  that  the  red  had  passed  through  the 
foramen  ovale  into  the  left  auricle  and  ventricle  and  arch  of  the 
aorta,  and  had  filled  the  vessels  of  the  head  and  upper  extremities : 
while  the  yellow  had  passed  into  the  right  ventricle,  pulmonary 
artery,  ductus  arteriosus,  and  thoracic  aorta,  with  only  a  slight  ad- 
mixture of  red  at  the  posterior  part  of  the  right  auricle.  All  the 
branches  of  the  thoracic  and  abdominal  aorta  were  filled  with  yel- 
low, while  the  whole  of  the  red  had  passed  to  the  upper  part  of  the 
body. 

We  have  repeated  the  above  experiment  several  times  on  the 
foetal  pig,  when  about  one-half  and  three-quarters  grown,  first  taking 
the  precaution  to  wash  out  the  heart  and  large  vessels  with  a  wa- 
tery injection,  immediately  after  the  removal  of  the  foetus  from  the 
body  of  the  parent,  and  before  the  blood  had  been  allowed  to  coagu- 
late. The  injections  used  were  blue  for  the  superior  vena  cava, 
and  yellow  for  the  inferior.  The  two  syringes  were  managed,  at 
the  same  time,  by  the  right  and  left  hands;  their  nozzles  being 
firmly  held  in  place  by  the  fingers  of  an  assistant.     When  the 


Diagram  of  CiRcaLATioN  through 
THE  FcETAL  HEART. — rt.  Superior  veaa 
cava.  6.  Inferior  vena  cava.  c,c,c,o  Arch 
of  aorta  and  its  branches,     d.  Pulmonary 

artery. 


'  Edinburgh  Medical  and  Surgical  Journal,  vol.  xliii.  1835. 


584       DEVELOPMENT    OF    THE    CIECULATORY    APPARATUS. 

points  of  the  syringes  were  introduced  into  the  veins,  at  equal  dis- 
tances from  the  heart,  and  the  two  injections  made  with  equal  force 
and  rapidity,  it  was  found  that  the  admixture  of  the  colors  which 
took  place  was  so  slight,  that  at  least  nineteen-twentieths  of  the  yellow 
injection  had  passed  into  the  left  auricle,  and  nineteen-twentieths  of 
the  blue  into  the  right.  The  pulmonary  artery  and  ductus  arteriosus 
contained  a  similar  proportion  of  blue,  and  the  arch  of  the  aorta  of 
yellow.  In  the  thoracic  and  abdominal  aorta,  however,  contrary  to 
what  was  found  by  Dr.  Eeid,  there  was  always  an  admixture  of  the 
two  colors,  generally  in  about  equal  proportions.  This  discrepancy 
may  be  owing  to  the  smaller  size  of  the  head  and  upper  extremities, 
in  the  pig,  as  compared  with  those  of  the  human  subject,  which  would 
prevent  their  receiving  all  the  blood  coming  from  the  left  ventricle ; 
or  to  some  differences  in  the  manipulations  of  these  experiments, 
in  which  it  is  not  always  easy  to  imitate  exactly  the  force  and  ra- 
pidity of  the  different  currents  of  blood  in  the  living  foetus.  The 
above  results,  however,  are  such  as  to  leave  no  doubt  of  the  prin- 
cipal fact,  viz.,  that  up  to  an  advanced  stage  of  foetal  life,  by  far  the 
greater  portion  of  the  blood  coming  from  the  inferior  vena  cava 
passes  through  the  foramen  ovale,  into  the  left  side  of  the  heart ; 
while  by  far  the  greater  portion  of  that  coming  from  the  head  and 
upper  extremities  passes  into  the  right  side  of  the  heart,  and  thence 
outward  by  the  pulmonary  trunk  and  ductus  arteriosus.  Toward 
the  latter  periods  of  gestation,  this  division  of  the  venous  currents 
becomes  less  complete,  owing  to  the  three  following  causes: — 

First,  the  lungs  increasing  in  size,  the  two  pulmonary  arteries, 
as  well  as  the  pulmonary  veins,  enlarge  in  proportion;  and  a  greater 
quantity  of  the  blood,  therefore,  coming  from  the  right  ventricle, 
instead  of  going  onward  through  the  ductus  arteriosus,  passes  to 
the  lungs,  and  returning  thence  by  the  pulmonary  veins  to  the  left 
auricle  and  ventricle,  joins  the  stream  passing  out  by  the  arch  of 
the  aorta. 

Secondly,  the  Eustachian  valve  diminishes  in  size.  This  valve, 
which  is  very  large  and  distinct  at  the  end  of  the  sixth  month 
(Fig.  252),  subsequently  becomes  atrophied  to  such  an  extent  that, 
at  the  end  of  gestation,  it  has  altogether  disappeared,  or  is  at  least 
reduced  to  the  condition  of  a  very  narrow,  almost  imperceptible 
membranous  ridge,  which  can  exert  no  influence  on  the  direction  of 
the  current  of  blood  passing  by  it.  Thus,  the  cavity  of  the  supe- 
rior vena  cava,  at  its  upper  extremity,  ceases  to  be  separated  from 


DEVELOPMENT    OF    THE    HEART.  585 

that  of  the  right  auricle;  and  a  passage  of  blood  from  one  to  the 
other  may,  therefore,  more  readily  take  place. 

Thirdly,  the  foramen  ovale  becomes  partially  closed  by  a  valve 
which  passes  across  its  orifice  from  behind  forward.  This  valve, 
which  begins  to  be  formed  at  a  very  early  period,  is  called  the 
valve  of  the  foramen  ovale.  It  consists  of  a  thin,  fibrous  sheet,  which 
grows  from  the  posterior  surface  of  the  auricular  cavity,  just  to  the 
left  of  the  foramen  ovale,  and  projects  into  the  left  auricle,  its  free 
edge  presenting  a  thin  crescentic  border,  and  being  attached,  by  its 
two  extremities,  to  the  auricular  septum  upon  the  left  side.  This 
valve  does  not  at  first  interfere  at  all  with  the  flow  of  blood  from 
right  to  left,  since  its  edge  hangs  freely  and  loosely  into  the  cavity 
of  the  left  auricle.  It  only  opposes,  therefore,  during  the  early 
periods,  any  accidental  regurgitation  from  left  to  right. 

But  as  gestation  advances,  while  the  walls  of  the  heart  con- 
tinue to  enlarge,  and  its  cavities  to  expand  in  every  direction,  the 
fibrous  bundles,  forming  the  valve,  do  not  elongate  in  proportion. 
The  valve,  accordingly,  becomes  drawn  downward  more  and  more 
toward  the  foramen  ovale.  It  thus  comes  in  contact  with  the  edges 
of  the  interauricular  septum,  and  unites  with  its  substance;  the 
adhesion  taking  place  first  at  the  lower  and  posterior  portion,  and 
proceeding  gradually  upward  and  forward,  so  as  to  make  the  pas- 
sage, from  the  right  auricle  to  the  left,  more  and  more  oblique  in 
direction. 

At  the  same  time,  an  alteration  takes  place  in  the  position  of  the 
inferior  vena  cava.  This  vessel,  which  at  first  looked  transversely 
toward  the  foramen  ovale,  becomes  directed  more  obliquely  for- 
ward ;  so  that,  the  Eustachian  valve  having  mostly  disappeared,  a 
part  of  the  blood  of  the  inferior  vena  cava  enters  the  right  auricle, 
while  the  remainder  still  passes  through  the  equally  oblique  open- 
ing of  the  foramen  ovale. 

At  the  period  of  birth  a  change  takes  place,  by  which  the 
foramen  ovale  is  completely  occluded,  and  all  the  blood  coming 
through  tiie  inferior  vena  cava  is  turned  into  the  right  auricle. 

This  change  depends  upon  the  commencement  of  respiration. 
A  much  larger  quantity  of  blood  than  before  is  then  sent  to  the 
lungs,  and  of  course  returns  from  them  to  the  left  auricle.  The 
left  auricle,  being  then  completely  filled  wath  the  pulmonary  blood, 
no  longer  admits  a  free  access  from  the  right  auricle  through  the 
foramen  ovale;  and  the  valve  of  the  foramen,  pressed  backward 
more  closely  against  the  edges  of  the  septum,  becomes  after  a  time 


586 


DEVELOPMENT    OF    THE    CIRCULATORY    APPARATUS. 


adherent  throughout  and  obliterates  the  opening  altogether.  The 
cutting  off  of  the  placental  circulation  diminishes  at  the  same  time 
the  quantity  of  blood  arriving  at  the  heart  by  the  inferior  vena 
cava.  It  is  evident,  indeed,  that  the  same  quantity  of  blood  which 
previously  returned  from  the  placenta  by  the  inferior  cava,  on  the 
right  side  of  the  auricular  septum,  now  returns  from  the  lungs,  by 
the  pulmonary  veins  upon  the  left  side  of  the  same  septum ;  and  it 
is  owing  to  all  these  circumstances  combined,  that  while  before  birth 
a  portion  of  the  blood  always  passed  from  the  right  auricle  to  the 
left  through  the  foramen  ovale,  no  such  passage  takes  place  after 
birth,  since  the  pressure  is  then  equal  on  both  sides  of  the  auricular 
septum. 

The  foetal  circulation,  represented  in  Fig.  253,  is  then  replaced 
by  the  adult  circulation,  represented  in  Fig.  254. 


Fig.  254. 


Diagram  of  Adult  Circulation  throuuh  the  Heart — a,  a.  Superior  and  inferior  venae 
cav33.  b.  Right  ventricle,  c.  Pulmonary  artery,  dividing  into  right  and  left  branches,  d.  Pulmo- 
nary vein.     e.  Left  ventricle.    /.  Aorta. 

That  portion  of  the  septum  of  the  auricles,  originally  occupied 
by  the  foramen  ovale,  is  accordingly  constituted,  in  the  adult  con- 
dition, by  the  valve  of  the  foramen  ovale,  whicb  has  become  adhe- 
rent to  the  edges  of  the  septum.  The  auricular  septum  in  the  adult 
heart  is,  therefore,  thinner  at  this  spot  than  elsewhere;  and  presents, 
on  the  side  of  the  right  auricle,  an  oval  depression,  termed  the  fossa 


DEVELOPMENT    OF    THE    HEART.  587 

ovalis^  which  indicates  the  site  of  the  original  foramen  ovale.  The 
fossa  ovalis  is  surrounded  by  a  slightly  raised  ring,  the  annulus 
ovalis,  representing  the  curvilinear  edge  of  the  original  auricular 
septum. 

The  foramen  ovale  is  sometimes  completely  obliterated  within  a 
few  daj^s  after  birth.  It  often,  however,  remains  partially  pervious 
for  several  weeks  or  months.  We  have  a  specimen,  taken  from  a 
child  of  one  year  and  nine  months,  in  which  the  opening  is  still 
very  distinct;  and  it  is  not  unfrequent  to  find  a  small  apertare  ex- 
isting even  in  adult  life.  In  these  instances,  however,  though  the 
adhesion  and  solidification  of  the  auricular  septum  is  not  complete, 
no  disturbance  of  the  circulation  results,  and  no  admixture  of 
blood  takes  place  between  the  right  and  left  sides  of  the  heart ; 
since  the  passage  through  the  auricular  septum  is  always  very 
oblique  in  its  direction,  and  its  valvular  arrangement  prevents  any 
regurgitation  from  left  to  right,  while  the  complete  filling  of  the 
left  auricle  with  pulmonary  blood,  as  above  mentioned,  equally 
opposes  any  passage  from  right  to  left. 


588  DEVELOPMENT    OF    THE    BODY    AFTER    BIRTH. 


CHAPTER    XVIII. 

DEVELOPMENT  OF   THE   BODY    AFTER   BIRTH. 

The  newly-born  infant  is  still  very  far  from  having  arrived  at  a 
state  of  complete  development.  The  changes  which  it  has  passed 
through  during  intra-uterine  life  are  not  more  marked  than  those 
which  are  to  follow  during  the  periods  of  infancy,  childhood,  and 
adolescence.  The  anatomy  of  the  organs,  both  internal  and  ex- 
ternal, their  physiological  functions,  and  even  the  morbid  derange- 
ments to  which  they  are  subject,  continue  to  undergo  gradual  and 
progressive  alterations,  throughout  the  entire  course  of  subsequent 
life.  The  history  of  development  extends,  properly  speaking,  from 
the  earliest  organization  of  the  embryonic  tissues  to  the  complete 
formation  of  the  adult  body.  The  period  of  birth,  accordingly, 
marks  only  a  single  epoch  in  a  constant  series  of  changes,  some  of 
which  have  preceded,  while  many  others  are  to  follow. 

The  weight  of  the  newly-born  infant  is  a  little  over  six  pounds. 
The  middle  point  of  the  body  is  nearly  at  the  umbilicus,  the  head 
and  upper  extremities  being  still  very  large,  in  proportion  to  the 
lower  extremities  and  pelvis.  The  abdomen  is  larger  and  the 
chest  smaller  in  proportion  than  in  the  adult.  The  lower  extremi- 
ties are  curved  inward,  as  in  the  foetal  condition,  so  that  the  soles  of 
the  feet  look  obliquely  toward  each  other,  instead  of  being  directed 
horizontally  downward,  as  at  a  subsequent  period.  Both  upper 
and  lower  extremities  are  habitually  curled  upward  and  forward 
over  the  chest  and  abdomen,  and  all  the  joints  are  constantly  in  a 
semi-flexed  position. 

The  process  of  respiration  is  very  imperfectly  performed  for 
some  time  after  birth.  The  expansion  of  the  pulmonary  vesicles, 
and  the  changes  in  the  circulatory  apparatus  described  in  the  pre- 
ceding chapter,  far  from  being  sudden  and  instantaneous,  are 
always  more  or  less  gradual  in  their  character,  and  require  an 
interval  of  several  days  for  their  completion.  Respiration,  indeed, 
seems  to  be  accomplished,  during  this  period,  to  a  considerable 


DEVELOPMENT    OF    THE    BODY    AFTER    BIRTH.  589 

extent  through  the  skin,  which  is  remarkably  soft,  vascular,  and 
ruddy  in  color.  The  animal  heat  is  also  less  actively  generated 
than  in  the  adult,  and  requires  to  be  sustained  by  careful  protec- 
tion, and  by  contact  with  the  body  of  the  mother.  The  young 
infant  sleeps  during  the  greater  part  of  the  time;  and  even  when 
awake  there  are  but  few  manifestations  of  intelligence  or  percep- 
tion. The  special  senses  of  sight  and  hearing  are  dull  and  inex- 
citable,  though  their  organs  are  perfectly  formed ;  and  even 
consciousness  seems  present  only  to  a  very  limited  extent.  Volun- 
tary motion  and  sensation  are  nearly  absent ;  and  the  almost  con- 
stant irregular  movements  of  the  limbs,  observable  at  this  time, 
are  evidently  of  a  reflex  or  automatic  character.  Nearly  all  the 
nervous  phenomena,  indeed,  presented  by  the  newly-born  infant, 
are  of  a  similar  nature.  The  motions  of  its  hands  and  feet,  the  act 
of  suckling,  and  even  its  cries  and  the  contortions  of  its  face,  are 
reflex  in  their  origin,  and  do  not  indicate  the  existence  of  any 
active  volition,  or  any  distinct  perception  of  external  objects. 
There  is  at  first  but  little  nervous  connection  established  with  the 
external  world,  and  the  system  is  as  yet  almost  exclusively  occu- 
pied with  the  functions  of  nutrition  and  respiration. 

This  preponderance  of  the  simple  reflex  actions  in  the  nervous 
system  of  the  infant,  is  observable  even  in  the  diseases  to  which  it 
is  peculiarly  subject  for  some  years  after  birth.  It  is  at  this  age 
that  convulsions  from  indigestion  are  of  most  frequent  occurrence, 
and  even  temporary  strabismus  and  paralysis,  resulting  from  the 
same  cause.  It  is  well  known  to  physicians,  moreover,  that  the 
effect  of  various  drugs  upon  the  infant  is  very  different  from  that 
which  they  exert  upon  the  adult.  Opium,  for  example,  is  very 
much  more  active,  in  proportion  to  the  dose,  in  the  infant  than  in 
the  adult.  Mercury,  on  the  other  hand,  produces  salivation  with 
greater  difficulty  in  the  former  than  in  the  latter.  Blisters  excite 
more  constitutional  irritation  in  the  young  than  in  the  old  subject; 
and  antimony,  when  given  to  children,  is  proverbially  uncertain 
and  dangerous  in  its  operation. 

The  difference  in  the  anatomy  of  the  newly -born  infant,  and  that 
of  the  adult,  may  be  represented,  to  a  certain  extent,  by  the  fol- 
lowing list,  which  gives  the  relative  weight  of  the  most  important 
internal  organs  at  the  period  of  birth  and  that  of  adult  age;  the 
weight  of  the  entire  body  being  reckoned,  in  each  case,  as  1000. 
The  relative  weight  of  the  adult  organs  has  been  calculated  from 


590 


DEVELOPMENT    OF    THE    BODY    AFTER    BIRTH. 


the  estimates  of  Cruveilhier,  Solly,  Wilson,  &c,;  that  of  the  organs 
in  the  foetus  at  term  from  our  own  observations. 


FcETDS  AT  Term. 

Adult. 

Weight 

of  the  entire  body 

.     1000.00 

1000.00 

"         encephalon 

.       148.00 

23.00 

"         liver  . 

37.00 

29.00 

"         heart  . 

7.77 

4.17 

"         kidneys 

6.00 

4.00 

"         renal  cap  ules 

l.t)3 

0.13 

"         thyroid  gland 

0.60 

0.51 

"         thymus  gland 

3.00 

0.00 

will  be  observed  that  most  of  the  internal  orcra 

ns  dimini 

relative  size  after  birth,  owing  principally  to  the  increased  develop- 
ment of  the  osseous  and  muscular  S3'-stems,  both  of  which  are  in  a 
very  imperfect  condition  throughout  intra-uterine  life,  but  which 
come  into  activity  during  childhood  and  youth. 

Within  the  first  day  after  birth  the  remains  of  the  umbilical 
cord  begin  to  wither,  and  become  completely  desiccated  by  about 
the  third  day.  A  superficial  ulceration  then  takes  place  about  the 
point  of  its  attachment,  and  it  is  separated  and  thrown  off  within 
the  first  week.  After  the  separation  of  the  cord,  the  umbilicus 
becomes  completely  cicatrized  by  the  tenth  or  twelfth  day  after 
birth.  (Guy.) 

An  exfoliation  and  renovation  of  the  cuticle  also  take  place 
over  the  whole  body  soon  after  the  birth.  According  to  Kolliker, 
the  eyelashes,  and  probably  all  the  hairs  of  the  body  and  head,  are 
thrown  off  and  replaced  by  new  ones,  within  the  first  year. 

The  teeth  in  the  newly-born  infant  are  but  partially  developed, 
and  are  still  inclosed  in  their  follicles,  and  concealed  beneath  the 
gums.  They  are  twenty  in  number;  viz.,  two  incisors,  one  canine, 
and  two  molars,  on  each  side  of  each  jaw.  At  birth  there  is  a  thin 
layer  of  dentine  and  enamel  covering  their  upper  surfaces,  but 
the  body  of  the  tooth  and  its  fangs  are  formed  subsequently  by 
progressive  elongation  and  ossification  of  the  tooth-pulp.  The 
fully-formed  teeth  emerge  from  the  gums  in  the  following  order. 
The  central  incisors  in  the  seventh  month  after  birth ;  the  lateral 
incisors  in  the  eighth  month;  the  anterior  molars  at  the  end  of  the 
first  year;  the  canines  at  a  year  and  a  half;  and  the  second  molars 
at  two  years  (Kolliker).  The  eruption  of  the  teeth  in  the  lower 
jaw  generally  precedes  by  a  short  time  that  of  the  corresponding 
teeth  in  the  upper. 

During  the  seventh  year  a  change  begins  to  take  place  by  which 


DEVELOPMENT    OF    THE    BODY    AFTER    BIRTH.  591 

the  first  set  of  teeth  are  thrown  oft'  and  replaced  by  a  second  or 
permanent  set,  differing  in  number,  size,  and  shape  from  those 
which  preceded.  The  anterior  permanent  molar  first  shows  itself 
just  behind  the  posterior  temporary  molar,  on  each  side.  This 
happens  at  about  six  and  a  half  years  after  birth.  At  the  end  of 
the  seventh  year  the  middle  incisors  are  thrown  oft"  and  replaced 
by  corresponding  permanent  teeth,  of  larger  size.  At  the  eighth 
year  a  similar  exchange  takes  place  in  the  lateral  incisors.  In  the 
ninth  and  tenth  years,  the  anterior  and  second  molars  are  replaced 
by  the  anterior  and  second  permanent  bicuspids.  In  the  twelfth 
year,  the  canine  teeth  are  changed.  In  the  thirteenth  year,  the 
second  permanent  molars  show  themselves;  and  from  the  seven- 
teenth to  the  twenty-first  year,  the  third  molars,  or  "  wisdom  teeth," 
emerge  from  the  gums,  at  the  posterior  extremities  of  the  dental 
arch.  (Wilson.)  The  jaw,  therefore,  in  the  adult  condition,  contains 
three  teeth  on  each  side  more  than  in  childhood,  making  in  all 
thirty-two  permanent  teeth ;  viz.,  on  each  side,  above  and  below, 
two  incisors,  one  canine,  two  bicuspids,  and  three  permanent 
molars. 

The  entire  generative  apparatus,  which  is  still  altogether  inactive 
at  birth,  begins  to  enter  upon  a  condition  of  functional  activity 
from  the  fifteenth  to  the  twentieth  year.  The  entire  configuration 
of  the  body  alters  in  a  striking  manner  at  this  period,  and  the  dis- 
tinction between  the  two  sexes  becomes  more  complete  and  well 
marked.  The  beard  is  developed  in  the  male ;  and  in  the  female 
the  breasts  assume  the  size  and  form  characteristic  of  the  condition 
of  puberty.  The  voice,  which  is  shrill  and  sharp  in  infancy  and 
childhood,  becomes  deeper  in  tone,  and  the  countenance  assumes  a 
more  sedate  and  serious  expression.  After  this  period,  the  mus- 
cular system  increases  still  further  in  size  and  strength,  and  the 
consolidation  of  the  skeleton  also  continues;  the  bony  union  of  its 
various  parts  not  being  entirely  accomplished  until  the  twenty-fifth 
or  thirtieth  year.  Finally,  all  the  different  organs  of  the  body  arrive 
at  the  adult  condition,  and  the  entire  process  of  development  is 
then  complete. 


INDEX. 


Absorption,  128 

by  bloodvessels,  131 

by  lacteals,  133 

of  fat,  137 

of  oxygen  in  respiration,  207 

by  egg  during  incubation,  508 

of  calcareous   matter  by  allantois, 
508 
Absorbent  glands,  134 

vessels,  133-136 
Acid,  carbonic,  206-217 

lactic,  in  gastric  juice,  107 

in  souring  milk,  277 

glyko-cliolic,  146 

tauro-cholic,  147 

pneumic,  211 

uric,  288-296 

oxalic,  in  urine,  301 
Acid  fermentation  of  urine,  300 
Acidity,  of  gastric  juice,  cause  of,  107 

of  urine,  295 
Acini,  of  liver,  279-280 
Adipose  vesicles,  58 

digestion  of,  126-127 
Adult  circulation,  570 

establishment  of,  585 
Aerial  respiration,  198-200 
Age,  influence  of,  on  exhalation  of  car- 
bonic acid,  215 

on  comparative  weight  of  organs,  590 
Air,  alterations  of,  in  respiration,  206 

circulation  of,  in  lungs,  204 
Air-cells  of  lungs,  200 
Air-chamber,  in  fowl's  egg,  454 
Albumen,  68 

of  the  blood,  189 

in  saliva,  93 

in  milk,  276 

of  the  egg,  how  produced,  453 

its  liquefaction  and  absorption  dur- 
ing development  of  foetus,  504-506 
Albuminoid  substances,  63 

digestion  of,  110 
Albuminose,  110 

interference   with   Trommer's    test, 
111 

with  action  of  iodine  and  starch,  112 


Alimentary  canal,  in  different  animals, 
84-88 

development  of,  546. 
Alkalies,  effect  of,  on  urine,  296 
Alkaline  chlorides,  39-42 

phosphates,  45 

carbonates,  44-45 
Alkaline  fermentation  of  urine,  302 
Alkalescence  of  blood,  due  to  carbonates, 

44 
Allantois,  501 

formation  of,  503 

in  fowl's  egg,  506 

function  of,  507 

in  foetal  pig,  524 
Alligator,  brain  of,  322 
Amnion,  501, 

formation  of,  502 

enlargement  of,  during  latter  part  of 
pregnancy,  532 

contact  with  chorion,  533 
Amniotic  folds,  502 
Amniotic  fluid,  532 

its  use,  533 

contains  sugar  at  a  certain  period,. 
551 
Amniotic  umbilicus,  502 
Analysis,  of  animal  fluids,  32-33 

of  milk,  80 

of  wheat  flour,  80 

of  oatmeal,  80 

of  eggs,  81 

of  meat,  81 

of  saliva,  92 

of  gastric  juice,  107 

of  pancreatic  juice,  123 

of  bile,  142 

of  blood-globules,  183 

of  blood-plasma,  188 

of  mucus,  269 

of  sebaceous  matter,  270 

of  perspiration,  272 

of  milk,  275 

of  butter,  277 

of  urine,  294 
Anoral   and   Gavakret,  production   of 
carbonic  acid  in  respiration,  214 


38 


594 


INDEX. 


Animal  functions,  27 
Animal  heat,  218 

in  different  species,  220 

mode  of  generation,  222-228 

influenced  by  local  causes,  226 

in  diffei'ent  organs,  227 

increase  of,  after  section  of  sympa- 
thetic nerve,  421-422 
Animal  and  vegetable  parasites,  434 
Animalcules,  infusorial,  431 

mode  of  production,  432 
Annulus  ovalis,  586 
Anterior  columns  of  spinal  cord,  321 

their  excitability,  343 
Aorta,  action  of,  247 

development  of,  571 
Aplysia,  nervous  system  of,  315 
Appetite,  disturbed  by  anxiety,  &c.,  117 

necessary  to  digestion  of  food,  118 
Aquatic  respiration,  197-198 
Area  pellucida,  492 

vasculosa,  505-567 
Arch  of  aorta,  formation  of,  571-572 
Arches,  cervical,  570 

transformation  of,  571 
Arteries,  246 

motion  of  blood  in,  247 

pulsation  of,  248 

elasticity  of,  246,  249 

rapidity  of  circulation  in,  250-251 

omphalo-mesenteric,  567 

vertebral,  570 

umbilical,  570 
Arterial  system,   development    of,  570- 

579 
Articulata,  nervous  system  of,  316 

reflex  action  in,  317 
Articulation  of  tapeworm,  443 
Arytenoid  cartilages,  205 

movements  of,  206 
Assimilation,  265 

destructive,  282 
Auricle,  single,  of  fish,  230 

double,  of  reptiles,  birds,  and  mam- 
malians, 231-232 

contraction  of,  245 
Auriculo-ventricular   valves,   action   of, 

234 
Auditory  nerves,  386 
Axis-cylinder,     of     nervous     filaments, 

308-310 
Aztec  children,  366 
Azygous  veins,  formation  of,  575 

Beaumont,  Dr.,   experiments  on  Alexis 

St.  Martin,  103-114 
Beknard,  on  efi'ect  of  dividing  Steno's 
duct,  99 
on  digestion  of  fat  in  intestine,  123 
on  formation  of  liver-sugar,  166, 167, 

168 
on  decomposition  of  bicarbonates  in 
lung,  212 


Bernard,  on  temperature  of  blood  in  dif- 
ferent organs,  2"i7 
Bidder  and  Schmidt,  on  daily  quantity 
of  bile,  153 

on  effect  of  excluding  bile  from  in- 
testine, 160 

on  reabsorption  of  bile,  161 
Bile,  141 

composition  of,  142 

tests  for,  150 

daily  quantity  of,  153 

functions  of,  158 

reabsorption,  161 

mode  of  secretion,  278 
Biliary  salts,  143 

of  human  bile,  149 
Biliverdine,  71,  142 

tests  for,  150 

passage  into  the  urine,  299 
Blastodermic  membrane,  490 
Blood,  178 

red  globules  of,  179 

white  globules,  185 

plasma,  188 

coagulation  of,  190 

bully  coat,  195 

entire  quantity  of,  196 

alterations  of,  in  respiration,  207 

temperature  of,  219 

in  different  organs,  227 

circulation  of,  229 

through  the  heart,  235 
through  the  arteries,  246 
through  the  veins,  252 
through  the  capillaries,  255 
Boussingault,  on  chloride  of  sodium  in 
food,  41 

on  internal  production  of  fat,  61 
Brain,  357 

of  alligator,  322 

of  rabbit,  323 

human,  326 

remarkable  cases  of  injury  to,  360 

size  of,  in  different  races,  364 
in  idiots,  366 

development  of,  540-541 
Branchiae,  197 

of  meno-branchus,  198 
Broad  ligaments,  formation  of,  563 
Bronchi,  division  of,  200 

ciliary  motion  in,  204 
Brunner's  glands,  120 
Buffy  coat  of  the  blood,  195 
Butter,  276 

composition  of,  277 

condition  in  milk,  59,  277 
Butyrine,  277 

Canals  of  Cuvier,  573 
Capillaries,  255 

their  inosculation,  256 

motion  of,  blood  in,  257 
Capillary  circulation,  256 


INDEX. 


595 


Capillary  circiUation,  causes  of,  258 

how  modified  by  inflammation,  259 
rapidity  of,  260 

peculiarities  of,  in   diflferent  parts, 
262,  264 
Caput  coli,  formation  of,  547 
Carbonic  acid,  in  the  breath,  206 

proportion  of,  to  oxygen  absorbed, 

207 
in  the  blood,  208 
origin  of,  in  lungs,  211 
in  the  blood,  212 
in  the  tissues,  212 
mode  of  production,  213 
daily  quantity  of,  214 
variations  of,  215 
exhaled  by  skin,  217 

by  egg,  during  incubation,  508 
absorbed  by  vegetables,  225 
Carbonate  of  lime,  44 
of  soda,  44 
of  potass,  45 

of  ammonia,  in  putrefying  urine,  302 
Cardiac  circulation,  in  foetus,  583 

in  adult,  586 
Carnivorous  animals,  respiration  of,  18, 
207 
urine  of,  287,  289 
Cartilagine,  70 
Caseine,  68 
Cat,  secretion  of  bile  in,  154 

closure  of  eyelids,  after  division  of 
sympathetic,  423 
Catalytic  action,  66 
of  pepsin,  110 
Centipede,  nervous  system  of,  316 
Centre,  nervous,  definition  of,  313 
Cerebrum,  359.     See  Hemispheres. 
Cerebral  ganglia,  322-357.     See  Hemi- 
spheres. 
Cerebellum,  370 

effects  of  injury  to,  371 
removal  of,  371,  372 
function  of,  370-373 
development  of,  540-541 
Cerebro-spinal  system,  318-319 

development  of,  539 
Cervix  uteri,  456 
in  fffitus,  564 
Cervical  arches,  570 

transformation  of,  571 
Changes,  in  egg,  while  passing  through 
oviduct,  450,  453,  488 
in  hepatic  circulation,  at  birth,  578 
in  comparative  size  of  organs,  after 
birth,  590 
Chick,  developmfent  of,  504-509 
Children,  Aztec,  366 
Chloride  of  sodium,  39 

its  proportion  in  the  animal  tissues 

and  fluids,  40 
importance  of,  in  the  food,  41 
mode  of  discharge  from  the  body,  41 


Chloride  of  sodium,  partial  decomposi- 
tion of,  in  the  body,  42 
Chloride  of  potassium,  42 
Cholesterine,  142 
Chorda  dorsalis,  493 
Chordse  vocales,  movement  of,  in  respi- 
ration, 205 
action  of,  in  the  production  of  vocal 

sounds,  403 
obstruction  of  glottis  by,  after  divi- 
sion of  pneumogastric,  405 
Chorion,  formation  of,  510 
villosities  of,  512 
source  of  vascularity  of,  513 
union  with  decidua,  521 
Chyle,  121-133 

in  lacteals,  136 
absorption  of,  137 

by  intestinal  epithelium,  138 
in  blood,  139 
Ciliary  motion,  in  bronchi,  204 

in  Fallopian  tubes,  475 
Ciliary  nerves,  414 
Circulation,  229 

in  the  heart,  222-235 

in  the  arteries,  246 

in  the  veins,  252 

in  the  capillaries,  255 

rapidity  of,  261 

peculiarities  of,  in  difi'erent  parts, 

263 
in  liver,  279 
in  placenta,  527-581 
Circulatory  apparatus,  development  of, 

566-587 
Civilization,   aptitude    for,   of    diflferent 

races,  364 
Classification  of  cranial  nerves,  387 
Clot,  formation  of,  191 

separation  from  serum,  192 
bulfed  and  cupped,  195 
Coagulation,  66 
"of  fibrin,  188 
of  blood,  190 

of  white  substance  of  Schwann,  in 
nerve-fibres,  309 
Colin,  on  unilateral  mastication,  94 
Cold,  resistance  to,  by  animals,  218 

efi'ect  of  when  long  continued,  219 
Colostrum,  275 
Coloring  matters,  70 
of  blood,  70,  183 
of  the  skin,  171 
of  bile,  71,  142 
of  urine,  71 
Commissure,  of  spinal  cord,  gray,  320 
white,  321 

transverse,  of  cerebrum,  327 
of  cerebellum,  327 
Commissures,  nervous,  313 

olfactory,  322,  385 
Congestion,  of  ear,  &c.,  after  division  of 
sympathetic,  422 


596 


IX TEX. 


Convolvulus,  sexual  apparatxis  of,  442 
Contact,  of  chorion  and  amnion,  533 

of  decidua  vera  and  reflexa,  534 
Consentaneons  action  of  muscles,  348 
Contraction,  of  stomacti  during  digestion, 
112 

of  spleen,  174 

of  blood-clot,  191 

of  diaphragm  and  intercostal  mus- 
cles, 201 

of  posterior  crico  arytenoid  nmscles, 
206 

of  ventricles,  239 

of  muscles  after  death,  328 

of  sphincter  ani,  354 

of  rectum,  354 

of  urinary  bladder,  355 

of  pupil,  under  influence  of  light, 
374,  418 
after  division  of  sympathetic, 
423 
Cookins,  effect  of,  on  food,  82 
Cord,  spinal,  319-340 

umbilical,  533 

withering  and  separation  of,  590 
Corpus  callosum,  327 
Corpus  luteum,  478 

of  menstruation,  478-482 

of  pregnancy,  482-487   ■ 

three  weeks  after  menstruation,  480 

four  weeks  after  menstruation,  481 

nine  weeks  after  menstruation,  481 

at  end   of   second  month  of  preg- 
nancy, 484 

at  end  of  fourth  month,  484 

at  term,  485 

disappearance  of,  after  delivery,  486 
Corpora  Malpighiana,  of  spleen,  174 
Corpora  striata,  323,  359 
Corpora  olivaria,  324 
Corpora  Wolffiana,  556-563 
CosTE,  on  rupture  of  Graafian  follicle  in 

menstruation,  474,  475 
Cranial  nerves,  385 

classification  of,  387 

motor,  388 

sensitive,  393 
Creatine,  287-288 
Creatinine,  288 
Cremaster  musc4e,  formation  of,  560 

function  of,  in  lower  animals,  561 
Crystals,  of  stearine,  55 

and  margarine,  56 

of  cholesterin,  143 

of  glyko-cholate  of  soda,  144,  145 

of  biliary  matters  of  dog's  bile,  148, 
155 

of  urea,  285 

of  creatine,  287 

of  creatinine,  288 

of  urate  of  soda,  289 

of  uric  acid,  296 

of  oxalic  acid,  302 


Crystals,  of  triple  phosphate,  304 
Crystallizable  substances  of  organic  ori- 
gin, 47 
Crossing  of  fibres  in  medulla  oblongata, 
324 
of  sensitive  fibres   in    spinal    cord. 

845 
of  streams  of  blood  in  fcetal  heart. 
582,  583 
Cecikshaxk,  rupture  of  Graafiian  folUcle 

in  menstruation,  474 
Cumulus  proligerus,  469 
Cutaneous  respiration,  217 

perspiration,  271 
Cuticle,  exfoliation  of,  during  fojtal  life, 
545 
after  birth,  590 
Cysticercus,  439 

transformation  of  into  taenia,  440 
production  of,  from  eggs  of  taenia, 
441 

Death,  a  necessary  consequence  of  life, 

428 
Decidua,  516 
vera,  518 
reflesa,  519 

union  with  chorion,  521 
its  discharge  in  cases    of   abortion, 
520  " 
at  the  time  of  delivery,  535 
Decussation  of  anterior  columns  of  spinal 
cord,  324 
of  optic  nerves,  375,  376 
Degeneration,  fatty,  of  muscular  fibres 

of  uterus,  after  delivery,  537 
Deglutition,  100 

retarded  by  division  of  Steno's  duct. 
99 
by  division  of  pneumogastric, 
401 
Dentition,  first,  590 

second,  591 
Descent  of  the  testicles,  559 

of  the  ovaries,  562 
Destructive  assimilation,  282 
Development   of  the   impregnated   egg, 

of  allantois,  503 

of  chorion,  510 

of  villosities  of  chorion,  511,  512 

of  decidua,  516 

of  placenta,  525-531 

ot  nervous  system,  539 

of  eye,  542 

of  ear,  543 

of  skeleton,  543 

of  limbs,  544 

of  integument,  545 

of  alimentary  canal,  546-548 

of  urinary  passages,  548 

of  liver,  550 

of  pharynx  and  oesophagus,  551 


IKDEX. 


597 


Development  of  face,  553 

of  Wolffian  bodies,  556 

of  kidneys,  557 

of  internal  generative  organs,  558 

of  circulatory  apparatus,  56b" 

of  arterial  system,  570 

of  venous  system,  573 

of  hepatic  circulation,  576 

of  heart,  578 

of  the  body  after  birth,  588 
Diabetes,  299 

in  foetus,  551 
Diaphragm,  action  of  in  breathing,  201, 
202 

formation  of,  552 
Diaphragmatic  hernia,  553 
Diet,  influence  of  on  nutrition,  74-76 

on  products  of  respiration,  207,  225 

on  formation  of  urea,  286 
of  urate  of  soda,  289 
Diffusion  of  gases  in  lungs,  203 
Digestion,  83 

of  starch,  118 

of  fats,  121,  123 

of  sugar,  119 

of  organic  substances,  110 

time  required  for,  114 
Digestive  apparatus  of  fowl,  85 

of  ox,  86 

of  man,  87 
Discharge  of  eggs  from  ovary,  450-453 

independent  of  sexual  intercourse, 
467 

mechanism  of,  470 

during  menstruation,  474 
Discus  proligerus,  469 
Distinction    between    corpora    lutea    of 
menstruation  and  pregnancy,  486-487 
Diurnal  variations,  in  exhalation  of  car- 
bonic acid,  216 

in  production  of  urea,  287 

in  density  and  acidity  of  urine,  293 
Division  of  nerves,  311 

of  heart,  into  right  and  left  cavities, 
579 
DoBSON,  on  variation  in  size  of  spleen, 

173 
Deafer,  John  C,  on  production  of  urea, 

286-287 
Drugs,  effect  of,  on  newly  born  infant, 

589 
Ductus  arteriosus,  580 

closure  of.  580-581 

venosus,  577 

obliteration  of,  578 
Duodenal  glands,  120 

fistuU,  156 
DuTKOCHET,  on  temperature  of  plants,  221 

Ear,  muscular  apparatus  of,  420 

development  of,  530 
Earthy  phosphates,  42,  45 

in  urine,  295 


Earthy  phosphates,  precipitated  by  addi- 
tion of  an  alkali,  296 
Ectopia  cordis,  553 
Egg,  442-446 

its  contents,  447 

where  formed,  448 

of  frog,  450 

of  fowl,  453-454 

changes  in,  while  passing  through 

the  oviduct,  450-453 
pre-existence  of,  in  ovary,  465 
development  of,  at  period  of  puberty, 

466 
periodical  ripening   and  discharge, 

467 
discharge  of,  from  Graafian  follicle, 

470 
impregnation  of,  how  accomplished, 

463-464 
development  of,  after  impregnation, 

488 
of  fowl,  showing  area  vasculosa,  505 
ditto,  showing  formation  of  allantois, 

506 
of  fish,  showing  vitelline  circulation, 

567 
attachment  of,  to   uterine   mucous 

membrane,  521 
discharge  of  from  uterus,  at  the  time 

of  delivery,  535 
condition  of  in  newly  born  infant, 
564 
Elasticity,  of  spleen,  173 

of  red  globules  of  blood,  181 
of  lungs,  200 
of  costal  cartilages,  202 
of  vocal  chords,  206 
of  arteries,  246 
Electrical  current,  effect  of,  on  muscles, 
329 
on  nerve,  331 

different  effects    of  direct   and   in- 
verse, 338 
Electrical  fishes,  phenomena  of,  337 
Electricity,  no  manifestations  of  in  irri- 
tated nerve,  338 
Elevation  of  temperature,  after  division 

of  sympathetic,  421,  422 
Elongation  of  heart  in  contraction,  240 

anatomical  causes  of,  241 
Embryo,  formation  of,  488 
Embryonic  spot,  492 
Encephalon,  321 

ganglia  of,  326 
Endosmosis,  of  fatty  substances,  137 

in  capillary  circulation,  260 
Enlargement   of  amnion,    during   preg- 
nancy, 532,  533 
Eutozoa,  encysted,  436 

mode  of  production,  438 
Epithelium,  in  saliva,  92 
of  gastric  follicles,  102 
of  intestine,  during  digestion,  138 


598 


INDEX. 


Epidermis,  exfoliation  of,  in  foetal  life,  545 

after  birth,  590 
Epididymis,  560 
Excretion,  282 

nature  of,  283 

importance  to  life,  283-284 

products  of,  284 

by  placenta,  530 
Excrementitious  substances,  282 

mode  of  formation  of,  283 

effect  of  retention  of,  283 
Exfoliation  of  cuticle,  during  fretal  life, 
545 

after  birth,  590 
Exhalation  of  watery  vapor,  39 

from  the  lungs,  207 

from  the  skin,  271 

from  the  egg,  during  incubation,  507 

of  carbonic  acid,  214-217 

of  nitrogen,  206 

of  animal  vapor,  206 
Exhaustion,  of  muscles,  by  repeated  irri- 
tation, 330 

of  nerves,  by  ditto,  332 
Expiration,  movements  of,  202 

after  section  of  pneumogastric,  407 
Extractive  matters  of  the  blood,  190 
Eye,   protection    of,   by   movements    of 
pupil,  374,  418 

by  two  sets  of  muscles,  419 
Eyeball,  inflammation  of,  after  division 

of  5th  pair,  397 
Eyelids,  formation  of,  543 

Face,  sensitive  nerves  of,  395 

motor  nerve,  390 

development  of,  553 
Facial  nerve,  390 

sensibility  of,  391 

influence  of,  on  muscular  apparatus 
of  eye,  419 

of  nose,  420 

of  ear,  420 

paralysis  of,  391 
Fallopian  tubes,  455 

formation  of,  559,  562 
Farinaceous  substances,  47. 

in  food,  48 

digestion  of,  118 
Fat,  decomposition  of,  in  the  blood,  137 
Fats,  54 

proportion  of,  in  dififerent  kinds  of 
food,  56 

condition,  in  the  various  tissues  and 
fluids,  57 

internal  source  of,  61 

decomposed  in  the  body,  62 

indispensable  as  ingredients  of  the 
food,  74 
Fatty  matters  of  the  blood,  189 
Fatty  degeneration  of  decidua,  536 

of  muscular  fibres  of  uterus,  after 
delivery,  537 


Female  generative  organs,  446 

of  frog,  449 

of  fowl,  453 

of  sow,  455 

of  human  species,  456 
development  of,  562 
Fermentation,  67 

of  sugar,  53 

acid,  of  urine,  300 

alkaline,  of  ditto,  302 
Fibrin,  68 

of  the  blood,  188 

coagulation  of,  188 

varying  quantity  of,  in  blood  of  dif- 
ferent veins,  189 
Fifth  pair  of  cranial  nerves,  394 

its  distribution,  395 

division  of,  paralyzes  sensibility  of 
face,  395 
and  of  nasal  passages,  396 
produces  inflammation  of  eye- 
ball, 397 

lingual  branch  of,  398 

small  root  of,  389 
Fish,  circulation  of,  230 

mode  of  progression,  370 

formation   of  umbilical  vesicle    in, 
498 

vitelline  circulation,  in  embryo  of, 
567 
Fish,  electrical,  phenomena  of,  337 
Fissure,  longitudinal,  of  brain  and  spinal 
cord,  319 

formation  of,  541 
Fissure  of  palate,  555 
Fistula,  gastric,  Dr.  Beaumont's  case  of, 
103 

mode  of  operating  for,  104 

duodenal,  156 
Foetal  circulation,  first  form  of,  566 

.  second  form  of,  568 
Follicles,  of  stomach,  101 

of  Lieberkiihn,  119 

of  Brunner's  glands,  120 

Graafian,  448,  470 

of  uterus,  517 
Food,  73 

composition  of,  80,  81 

daily  quantity  required,  81 

effect  of  cooking,  on,  82 
Foramen  ovale,  581 

valve  of,  585 

closure  of,  585 
Force,  nervous,  nature  of,  335 
Formation  of  sugar  in  liver,  165 

in  foetus,  551 
Fossa  ovalis,  586 
Functions,  animal,  27 

vegetative,  27 

of  teeth,  89 

of  saliva,  98 

of  gastric  j,uice,  109 

of  intestinal  juices,  118 


INDEX. 


599 


Functions,  of  pancreatic  juice,  123 
of  bile.  158 
of  spleen,  175 
of  nuicus,  2G9 
of  sebaceous  matter,  270 
of  perspiration,  272 
of  the  tears,  274 

Galvanism,  action  of,  on  muscles,  329 

on  nerves,  331 
Ganglion,  of  spinal  cord,  348 

of  tuber  annulai-e,  377 

of  mediilla  oblongata,  378 

Casserian,  393 

of  Andersch,  393,  398 

pneumogastric,  393,  400 

ophthalmic,  414 

spheno-palatine,  414 

submaxillary,  414 

otic,  415 

semilunar,  416 

impar,  416 
Ganglionic  system  of  nerves,  319,414 
Ganglia,  nervous,  312 

of  radiata,  313 

of  moUusca,  315 

of  articulata,  316 

of  posterior  roots  of  spinal  nerves, 
320 

of  alligator's  brain,  322 

of  rabbit's  brain,  323 

of  medulla  oblongata,  324,  378 

of  human  brain,  326 

of  great  sympathetic,  414 
Gases,  diffusion  of,  in  lungs,  203 

absorption    and   exhalation   of,   by 
lungs,  208 
by  the  tissues,  212 
Gastric  follicles,  101 
Gastric  juice,  mode  of  obtaining,  105 

composition  of,  107 

action  on  food,  109 

interference  with  Trommer's  test.  Ill 

interference  with   action  of  starch 
and  iodine,  112 

daily  quantity  of,  115 

solvent  action  of,  on  stomach,  after 
death,  117 
Gelatine,  how  produced,  32 

effect  of  feeding  animals  on,  77 
Generation,  429 

spontaneous,  429 

of  infusoria,  432 

of  parasites,  434 

of  encysted  entozoa,  436 

of  tsenia,  438 

sexual,  by  germs,  442 
Germ,  nature  of,  442 
Germination,  heat  produced  in,  221 
Germinative  vesicle,  447 

disappearance  of,  in  mature  egg,  488 
Germinative  spot,  447 
Gills,  of  fish,  197 


Gills,  of  menobranchus,  198 
Glands,  of  Brunner,  120 
mesenteric,  134 
vascular,  175 
Meibomian,  270 
perspiratory,  271 
action  of,  in  secretion,  265 
Glandulse,  solitariae  and  agminatse,  128 
Globules,  of  blood,  178 
red,  179 

different  appearances  of,  under 

microscope,  179,  180 
mutual  adhesion  of,  180 
color,  consistency,  and  structure 

of,  181 
action  of  water  on,  182 
composition  of,  183 
size,  &c.,  in  different  animals, 
184,185 
white,  185 

action  of  acetic  acid  on,  186 
red  and  white,  movement  of,  in 
circulation,  257 
Globuline,  68,  183. 
Glomeruli,  of  Wolffian  bodies,  557 
Glosso -pharyngeal  nerve,  398 

action  of,  in  swallowing,  399 
Glottis,  movements  of,  in  respiration,  204 
in  formation  of  voice,  402 
closure  of,  after  section  of  pneumo- 
gastrics,  405 
Glycine,  146 
Glyco-cholic  acid,  146 
Glyco-cholate  of  soda,  146 
its  crystallization,  144 
Glycogenic  function  of  liver.  165 

in  foetus,  551 
Glycogenic  matter,  169 

its  conversion  into  sugar,  170 
Graafian  follicles,  448 
structure  of,  469 

rupture  of,  and  discharge  of  egg,  470 
ruptured  during  menstruation,  474 
condition  in  foetus  at  term,  564 
Gray  substance,  of  nervous  system,  312 
of  spinal  cord,  320 
of  brain,  326 

its  want  of  irritability,  360 
Great  sympathetic,  319-414 
anatomy  of,  415 

sensibility  and  excitability  of,  417 
connection  of,  with  special  senses, 

418,  421 
division  of,  influence  on  animal  heat, 

422 
on  pupil  and  eyelids,  423 
reflex  actions  of,  424 
Gubernaculum  testis,  560 

function  of,  in  lower  animals,  561 
Gustatory  nerve,  398 

Hammoxd,    Dr.    Wm.    A.,    on    effects    of 
non-nitrogenous  diet,  76 


600 


INDEX. 


Hammoxd,  on  production  of  urea,  2^6 

Hsematine,  70,  183 

Hairs,  formation  of,  in  embryo,  545 

Hare-lip,  554 

Harvey,  on  motions  of  heart.  238,  240, 

245 
Heart,  230 

of  fish,  230 
of  reptiles,  231 
of  mammalians,  232 
of  man,  233 

circulation  of  blood  through,  235 
sounds  of,  235 
movements  of,  238 
impulse,  244 
development  of,  578 
Heat,  vital,  of  animals,  218 
of  plants,  221 
how  produced,  222 
increased  by  division  of  sympathetic 
nerve,  422 
Hemispheres,  cerebral,  322,  359 

remarkable  cases  of  injury  to,  360 
eifect  of  removal,  on  pigeons,  361- 

362 
effect  of  disease,  in  man,  363 
comparative  size  of,  in  different  races , 

364 
functions  of,  365 
development  of,  540 
Hemorrhage,  from  placenta,  in  parturi- 
tion, 535 
Hepatic  circulation,  279 
development  of,  576 
Herbivorous  animals,  respiration  of,  18, 
207 
urine  of,  287,  289 
Hernia,  congenital,  diaphragmatic,  553 

umbilical,  548 
Hernia,  inguinal,  562 
Hippurate  of  soda,  289 
Hunger  and  thirst,  continue  after  divi- 
sion of  pneumogastric,  411 
Hydrogen,  displacement  of  gases  in  blood 
by,  209 
exhalation  of  carbonic  acid  in  an 
atmosphere  of,  213 
Hygroscopic    property   of    organic    sub- 
stances, 65 
Hypoglossal  nerve,  392.    See  Sublingual. 

Impulse,  of  heart,  244 
Infant,  newly-born,  characteristics  of,  588 
Inflammation,  changes  of  capillary  cir- 
culation in,  259 
of  eyeball,  after  division  of  5th  pair, 
397 
Infusoria,  431 

different  kinds  of  432 
conditions  of  their  production,  432 
Schultze's  experiment  on  generation 
of,  434 
Inguinal  hernia,  congenital,  562 


Injection  of  placental  sinuses  from  ves- 
sels of  uterus,  529 
Inorganic  substances,  as  proximate  prin- 
ciples, 37 

their  source  and  destination,  46 
Inosculation,  of  veins,  253 

of  capillaries,  256-257 

of  nerves,  312 
Insalivation,  92 

importance  of,  99 

function  of,  100 
Inspiration,  how  accomplished,  201 

movements  of  glottis  in,  205 
Instinct,  nature  of,  382,  383 
Integument,  respiration  by,  217 

development  of,  545 
Intellectual  powers,  364-383 

in  animals,  384 
Intestine,  of  fowl,  85 

of  man,  87 

juices  of,  118 

digestion  in,  118,  127 

epithelium  of,  138 

disappearance  of  bile  in,  158 

development  of,  494,  495,  499,  547 
Intestinal  digestion,  125 
Intestinal  juices,  118 

action  of,  on  starch,  119 
Involution  of  uterus  after  delivery,  537 
Iris,  movements  of,  374,  418 

after  division  of  sympathetic,  423 
Irritability,  of  gastric  mucous  membrane, 
105 

of  the  heart,  241 

of  muscles,  328 

of  nerves,  330 

Jackson,  Prof.  Samuel,  on  digestion  of  fat 

in  intestine,  122 
Jaundice,  142 

yellow  color  of  urine  in,  299 

Kidneys,  peculiarity  of  circulation   in, 
263 
elimination  of  medicinal  substances 

by,  298 
formation  of,  557 
KiJCHENMEiSTER,  experiments  on  produc- 
tion of  tcenia  from  cysticercus, 
440 
of    cysticercus     from    eggs    of 
tjenia,  441 

Lachrymal  secretion,  273 

its  function,  274 
Lactation,  274 

variations  in  composition  of  milk 
during,  275-278 
Lacteals,  134-135 

and  lymphatics,  136 
Larynx,  action  of,  in  respiration,  205 
in  formation  of  voice,  402 

nerves  of,  400 


INDEX. 


601 


Larynx,  protective  action  of,  404 

movements  in  respiration,  205,404 
Layers,  external  and  internal,  of  blasto- 
dermic membrane,  490 
Lead,  salts  of,  action  in  distinguishing 

the  biliary  matters,  145-14(3 
Lehmann,  on  formation  of  carbonates  in 
blood,  45 
on  total  quantity  of  blood,  196 
on  effects   of  non-nitrogenous  diet, 
76 
Ledckakt,  on  production  of  cysticercus, 

441 
Ligament  of  the  ovary,  formation  of,  563 
Limbs,  formation  of,  in  frog,  496 
in  human  eraWyo,  544 
Liver,  vascularity  of,  279 
lobules  of,  280 
secreting  cells,  281 
formation  of  sugar  in,  165 
congestion  of,  after  feeding,  172 
development  of,  560,  576 
Liver  cells,  280 

their  action  in  secretion,  281 
Liver-sugar,  formation  of,  165 
after  death,  168 
in  foetus,  551 
Lobules,  of  lung,  200 

of  liver,  279 
Local  production  of  carbonic  acid,  212 

of  animal  heat,  226 
Local  variations  of  cii'culation,  263 
LoNGET,   on  interference   of  albuminose 
with  Trommer's  test.  Ill 
on  sensibility  of  glosso-pharyngeal 

nerve,  398 
on    irritability    of    anterior    spinal 
roots,  343 
LoNGET  AND   Matteucci,  experiment  on 
signs    of    electricity   in    an    irritated 
nerve,  338 
Lungs,  structure  of,  in  reptiles,  199 
in  man,  200 
alteration  of,  after  division  of  pneu- 
mogastrics,  407 
Lymph,  135 
Lymphatics,  133 

Magnus,  on  proportions  of  oxygen  and 

carbonic  acid  in  blood,  209 
Male  organs  of  generation,  458 

development  of,  558 
Malpighian  bodies  of  spleen,  174 
Mammalians,  circulation  in,  231 
Mammary  gland,  structure  of,  274 

secretion  of,  275 
Mastication,  89 

unilateral,  in  ruminating  animals, 
94 

retarded  by  suppressing  saliva,  99 
Meconium,  549 
Medulla  oblongata,  324,  378 

ganglia  of,  325-326 


Medulla  oblongata,  reflex  action  of,  379- 
382 
effect  of  destroying,  381 

development  of,  540 
Meibomian  glands,  270 
Melanine,  71 

Membrane,  blastodermic,  490 
Membrana  granulosa,  469 
Membrana  tympani,  action  of,  421 
Memory,    connection   of,    with    cerebral 

hemispheres,  362 
Menobranchus,  size  of  blood-globules  in, 
185 

gills  of,  198 

spermatozoa  of,  459 
Menstruation,  472 

commencement  and  duration  of,  473 

phenomena  of,  473 

rupture  of  Graafian  follicles  in,  474 

suspended   during   pregnancy,  473, 
486 
Mesenteric  glands,  134 
Michel,  Dr.  Myddleton,  rupture  of  Graaf- 
ian follicle  in  menstruation,  474 
Milk,  274 

composition  and  properties  of,  275 

microscopic  characters,  276 

souring  and  coagulation  of,  277 

variations  in,  during  lactation,  278 
Milk-sugar,  51,  52 

converted  into  lactic  acid,  277 
Mollusca,  nervous  system  of,  315 
Moore   and    Pennock,    experiments    on 

movements  of  heart,  240 
Motor  cranial  nerves,  388 
Motor  nervous  fibres,  315 
Motor  oculi  communis,  389 

externus,  389 
Movements,  of  stomach,  112 

of  intestine,  130 

of  heart,  238 

of  chest  in  respiration,  201 

of  glottis,  204 

associated,  348 

of  foetus,  533 
Mucosine,  69 
Mucous  follicles,  268 
Mucous  membrane,  of  stomach,  101 

of  intestine,  119,  128,  129 

of  uterus,  516 
Mucus,  268 

composition  and  properties  of,  269 

of  mouth,  93 

of  cervix  uteri,  456 
Muscles,  irritability  of,  328 

directly   paralyzed    by  sulpho-cya- 
nide  of  potassium,  330 

consentaneous  action  of,  348 

of  respiration,  201-202 
Muscular  fibres,  of  spleen,  173 

of  heart,  spiral  and  circular,  242 
Muscular  irritability,  328 

duration  after  death,  329 


602 


INDEX. 


Muscular  irritability,  esliausted  by  re- 
peated irritation,  330 
Masculine,  70 

Nails,  formation  of,  in  embryo,  545 
NtGEiEE,  on  rupture  of  Graafian  follicle, 

in  menstruation,  474 
Nerve-cells,  312 
Nerves,  division  of,  311 
inosculation  of,  312 
irritability  of.  32S 
spinal,  319,  320,  342 
cranial,  385 
olfactory,  385 
optic,  386 
auditory,  386 
oculo-motorius,  389 
patheticus,  389 
motor  externus,  3S9 
masticator,  389 
facial,  390 
sublingual,  392 
spinal  accessory,  392 
trifacial  (oth  pair),  394 
glosso-pbaryngeal,  398 
pneumogastric,  399 
superior  and  inferior  laryngeal,  400 
great  sympathetic,  414 
Nervous  filaments,  308 
of  brain,  309 
of  sciatic  nerve,  310 
motor  and  sensitive,  343 
Nervous  force,  tow  excited,  330 
nature  of,  335 

mode  of  transmission,  336-339 
Nervous  tissue,  two  kinds  of,  307 
Nervous  irritability,  328 
how  shown,  331 
duration  of,  after  death,  331 
exhausted  by  excitement,  332 
destroyed  by  woorara,  333 
distinct  from  muscular,  335 
nature  of,  335-339 
Nervous  system,  305 

general  structure  and  functions  of, 

305-327 
of  radiata,  313 
of  moUusca,  315 
of  articulata,  316 
of  vertebrata,  318 
reflex  action  of,  314 
Network,  capillary,  in   Peyer's   glands, 
128 
in  web  of  frog's  foot,  256 
in  lobule  of  liver,  280 
Newly-born  infant,  weight  of,  558 
respiration  in,  558 
nervous  phenomena  of,  589 
comparative  size  of  organs  in,  590 
Newport,  on  temperature  of  insects,  221 
Nitric  acid,   action  of,  on  bile-pigment, 
150 
precipitation  of  uric  acid  by,  295 


Nitrogen,  exhalation  of.  in   respiration, 

206"' 
Nutrition,  26-29 

Obliteration,  of  ductus  venosus,  578 

of  ductus  arteriosus,  580 
Oculo-motorius  nerve,  389 
CEsophagus,  paralysis  of,  after  division 
of  pneumogastric,  401 
development  of,  552 
CEstruation,  phenomena  of,  471 
Oleaginous  substances,  54 

in  difi'erent  kinds  of  food,  56 
condition  of,  in  the  tissues  and  fluids, 

57 
partly  pirodTTced  in  the  body,  61 
decomposed  in  the  body,  62 

in  the  blood,  137 
indispensable  as  ingredients  of  the 

food,  74 
insuiEcient  for  nutrition,  76 
Olfactory  apparatus,  protected    by  two 
sets  of  muscles,  420 

commissures,  322,  323,  385 
Olfactory  ganglia,  322 

their  function,  358 
Olfactory  nerves,  385 
Olivary  bodies,  324 
Omphalo-mesenterio  vessels,  567-569 
Ophthalmic  ganglion,  414 
Optic  ganglia,  322,  373 
Optic  nerves,  386 

decussation  of,  375-376 
Optic  thalami,  323,  359 

development  of,  540 
Organs  of  special  sense,  development  of, 

542 
Organic  substances,  63 

indefinite  chemical  composition  of, 

64 
hygroscopic  properties,  65 
coagulation  of,  66 
catalytic  action,  66 
putrefaction,  67 
source  and  destination,  72 
digestion  of,  110 
Origin,  of  plants  and  animals,  429 
of  infusoria,  431 
of  animal  and  vegetable  parasites, 

434 
of  encysted  entozoa,  436 
Ossification  of  skeleton,  544 
Osteine,  70 
Otic  ganglion,  415 
Ovary,  443 

of  tfenia,  443 
of  frog,  449 
of  fowl,  453 

of  human  female,  455,  456 
Ovaries,  descent  of,  in  foetus,  562 

condition  at  birth,  564 
Oviparous  and  viviparous  animals,  dis- 
tinction between,  465 


INDEX. 


603 


Oxalic  acid,  produced  in  urine,  302 
Oxygen,  absorbed  in  respiration,  207 
state  of  solution  in  blood,  209 
dissolved  by  blood-globules,  210 
absorbed  by  tbe  tissue-,  212 
exhaled  by  plants,  225 

Palate,  formation  of,  555 
Pancreatic  juice,  121 

mode  of  obtaining,  122 
composition  of,  123 
action  on  fat,  123 
daily  quantity  of,  123 
Pancreatine,  68 

in  pancreatic  juice,  123 
Panizza,  experiment  on  absorption   by 

bloodvessels,  131 
Paralysis,  after  division  of  anterior  root 
of  spinal  nerve,  341 
direct,  after  lateral  injury  of  spinal 

cord,  344 
crossed,  after  lateral  injury  of  brain, 

345 
facial,  341,  391 

of  muscles,  by  sulplio-cyanide  of  po- 
tassium, 330,  352 
of  motor  nerves,  by  woorara,  353 
of  sensitive  nerves,  by  strychnine, 

353 
of  voluntary  motion  and  sensation, 
after  destroying   tuber  annulare, 
377 
of   pharynx   and   oesophagus,    after 

section  of  pneumogastrics,  401 
of  larynx,  402-412 
of  muscular  coat  of  stomach,  411 
Paraplegia,  reflex  action  of  spinal  cord, 

in,  351 
Parasites,  434 

conditions  of  development  of,  435 
mode    of    introduction   into    body, 

436 
sexless,  reproduction  of,  436-441 
Parotid  saliva,  93 
Parturition,  534-535 
Par  vagum,  399.     See  Pneumogastric 
Patheticus  nerve,  389 
Pelvis,  development  of,  554 
Pennock    and    Moore,    experiments    on 

movements  of  heart,  240 
Pepsine,  69 

in  gastric  jxiice,  108 
Perception  of  sensations,  afterremoval  of 
hemispheres,  362 
destroyed,    after  removal   of  tuber 
annulare,  377 
Periodical  ovulation,  465 
Peristaltic  motion,  of  stomach,  112-113 
of  intestine,  130 
of  oviduct,  450-452 
of  Fallopian  tubes,  475 
Perspiration,  271 

daily  quantity  of,  272 


Perspiration,  composition  and  properties 
of,  272 
function,  in  regulating  temperature, 
273 
Pettenkofer's  test  for  bile,  151 
Peyer's  glands,  128 
Pharynx,  action  of,  in  swallowing,  40l 

formation  of,  551 
Phosphate  of  lime,  its  proportion  in  the 
animal  tissues  and  fluids,  42 
in  the  urine,  295 
precipitated  by  alkalies,  296 
Phosphate,  triple,   in  putrefying  urine, 

304 
Phosphates,  alkaline,  45 
in  urine,  295 
earthy,  42-45 

in  urine,  295 
of    magnesia,     soda,    and     potass, 
45 
Phosphorus,  not  a  proximate  principle, 

31 
Physiology,  definition  of,  17 
Phrenology,  367 

objections  to,  368 
practical  difficulties  of,  368-369 
Pigeon,  after  removal  of  cerebrum,  362 

of  cerebellum,  372 
Placenta,  523 

comparative  anatomy  of,  524 
formation  of,  in  human  species,  525 
.  foetal  tufts  of,  527 
maternal  sinuses  of,  527 
injection  of,  from  uterine  vessels,  529 
function  of,  530 
separation  of,  in  delivery,  535 
Placental  circulation,  568,  570 
Plants,  vital  heat  of,  221 

generative  apparatus  of,  442 
Plasma  of  the  blood,  187 
Pneumic  acid,  21] 
Pneumogastric  nerve,  399 
its  distribution,  400 
action  of,  on  pharynx  and  oesopha- 
gus, 401 
on  larynx,  402 
in  formation  of  voice,  403 
in  respiration,  404 
effect  of  its  division,  on  respiratory 

movements,  406-407 
cause   of    death   after   division   of, 

409-410 
influence  of,  on  oesophagus  and  sto- 
mach, 411-412 
Pneumogastric  ganglion,  400 
PoGGiALE,  on  glycogenic  matter  in  but- 
cher's meat,  170 
Pons  Varolii,  324,  327 
Portal  blood,  quantity  of  fibrin  in,  189 

temperature  of,  227 
Portal  vein,  in  liver,  279 
development  of,  576 
Posterior  columns  of  spinal  cord,  321 


604 


INDEX. 


Primitive  trace,  492 
Production,  of  sugar  in  liver,  165 

of  carbonic  acid,  214 

of  animal  heat,  218 

of  urea  in  blood,  285 

of  infusorial  animalcules,  431 

of  animal  and  vegetable  parasites, 
434 
Proximate  principles,  29 

definition  of,  31 

mode  of  extraction,  32 

manner  of  their  association,  33 

varying  proportions  of,  34 

three  distinct  classes  of,  35 
Proximate  principles  of  the    first   class 
(inorganic),  37 

of  the  second  class   (crystallizable 
substances  of  organic  origin),  47 

of    the   third   class     (organic    sub- 
stances), QS 
Ptyaline,  93 
Puberty,  period  of,  467 

signs  of,  in  female,  472 
Pulsation,  of  heart,  235 

in  living  animal,  239 

of  arteries,  247,  248 
Pupil,  action  of,  374,  418 

contraction  of,  after  division  of  sym- 
pathetic, 423 
Pupillary  memi)rane,  542 
Putrefaction,  67 

of  the  urine,  300 
Pyramids,   anterior,  of  medulla    oblon- 
gata, 324 

Quantity,  daily,  of  water  exhaled,  39 

of  food,  81 

of  saliva,  96 

of  gastric  juice,  114 

of  pancreatic  juice,  123 

of  bile,  153 

of  carbonic  acid  exhaled,  214 

of  perspiration,  272 

of  urine,  291 

of  urea,  286 

of  urate  of  soda,  289 
Quantity,  entire,  of  blood  in  body,  196 

Rabbit,  brain  of,  323 

Races  of  men,  different  capacity  of,  for 

civilization,  364 
Radiata,  nervous  system  of,  313 
Rapidity  of  circulation,  261 

of    transmission   of  nervous    force, 
336-337 
Reactions,  of  starch,  50 

of  sugar,  52 

of  fat,  54 

of  saliva,  93 

of  gastric  juice,  107-108 

of  intestinal  juice,  121 

of  pancreatic  juice,  123 

of  bile,  150 


Reactions,  of  mucus,  269 

of  milk,  276 

of  urine,  295 
Reasoning  powers,  363-364 

in  animals,  383 
Red  globules  of  blood,  179 
Reflex  action,  314 

in  centipede,  317 

of  spinal  cord,  348,  382 

of  medulla  oblongata,  379,  382 

of  tuber  annulare,  378,  382 

of  brain,  383 

of  optic  tubercles,  384 

in  newly  born  infant,  589 
Regeneration,  of  uterine  mucaus  mem- 
brane after  pregnancy,  536 

of  walls  of  uterus,  537-538 
Regnault  and  Reiset,  on  absorption  of 

oxygen,  225 
Reid,  Dr.  John,  experiment  on  crossing 

of  streams  in  foetal  heart,  583 
Reproduction,  427 

nature  and  object  of,  427-429 

of  parasites,  434 

of  tasnia,  438 

by  germs,  442 
Reptiles,  circulation  of,  231 
Respiration,  197 

by  gills,  198 

by  lungs,  199 

by  skin,  217 

changes  in  air  during,  206 

changes  in  blood,  207 

of  newly  born  infant,  588 
Respiratory  movements  of  chest,  201 

of  glottis,  204 

after  section  of  pneumogastrics,404- 
406 

after  injury  of  spinal  cord,  380 
Restiform  bodies,  325 
Rhythm  of  heart's  movements,  244 
Rotation   of    heart    during    contraction, 

243 
Round  ligament  of  the  uterus,  formation 
of,  563 

of  liver,  578 
Rumination,  movements  of,  94 
Rupture  of  Graafian  follicle,  470 

in  menstruation,  474 
Rutting  condition,  in  lower  animals,  471 

Saccharine  substances,  51,  52,  54 

in  stomach  and  intestine,  118 

in  liver,  165 

in  blood,  171 

in  urine,  299 
Saliva,  92 

different  kinds  of,  93 

daily  quantity  of,  96 

action  on  boiled  starch,  96 

variable,  97 

does  not  take  place  in  stomach,  98 

physical  function  of  saliva,  98 


INDEX. 


605 


Saliva,   quantity   absorbed  by  difTerent 

kinds  of  food,  100 
Salivary  glands,  93 
Salts,  biliary,  143 
of  the  blood,  190 
of  urine,  288 
Saponification,  of  fats,  55 
ScuAKLiNG,  on  diurnal  variations  in  exha- 
lation of  carbonic  acid,  216 
ScHULTZE,   experiment  on  generation  of 

infusoria,  434 
Scolopendra,  nervous  system  of,  316 
Sebaceous  matter,  269 

composition  and  properties  of,  270 
function  of,  271 
in  foetus,  545 
Secretion,  265 

varying  activity  of,  267 
of  saliva,  93 
of  gastric  juice,  105 
of  intestinal  juice,  120 
of  pancreatic  juice,  122 
of  bile,  153,  278 
of  sugar  in  liver,  165 
of  mucus,  268 
of  sebaceous  matter,  269 
of  perspiration,  271 
of  the  tears,  273 
of  bile  in  foetus,  551 
Segmentation  of  the  vitellus,  489 
Seminal  fluid,  458 

mixed  constitution  of,  462 
Sensation,  remains  after  destruction  of 
hemispheres,  362 
lost  after  removal  of  tuber  annulare, 

377 
special,  conveyed  by  pneumogastric 
nerve,  379,  406 
Sensation  and  motion,  distinct  seat  of,  in 
nervous  system,  340 
in  spinal  cord,  343 
Sensibility,  of  nerves  to  electric  current, 
337 
and  excitability,  definition  of,  341 
seat  of,  in  spinal  cord,  343 
in  brain,  357 
of  facial  nerve,  391 
of  sublingual  nerve,  392 
of  spinal  accessory,  393 
of  great  sympathetic,  417 
Sensibility,  special,  of  olfactory  nerves, 
385 
of  optic  nerves,  386 
of  auditory  nerves,  386 
of  lingual  branch  of  5th  pair,  398 
of  glosso-pharyngeal,  399 
of  pneumogastric,  408 
Sensitive  nervous  filaments,  315 
Sensitive   fibres,  crossing  of,  in   spinal 
cord,  345 
of  facial  nerve,  source  of,  390 
Sensitive  cranial  nerves,  393 


Septa,  inter-auricular  and  inter- ventricu- 
lar, formation  of,  581 
S£quakd,  on  crossing  of  sensitive  fibres 

in  spinal  cord,  345 
Serum,  of  the  blood,  192 
Sexes,  distinctive  characters  of,  444 
Sexless  entozoa,  436 
Sexual  generation,  442 
Shock,  effect  of,  in  destroying  nervous 

irritability,  330 
SiEBOLD,   on   production   of   tienia   from 

cysticercus,  440 
Sinus  terminalis,  of  area  vasculosa,  505 
Sinuses,  placental,  527 
Skeleton,  development  of,  543 
Skin,  respiration  by,  217 

sebaceous  glands  of,  269 
perspiratory  glands  of,  271 
development  of,  545 
Smell,  ganglia  of,  358 
nerves  of,  385 

injured  by  division  of  5tli  pair,  396 
Smith,  Dr.  Southwood,  on  cutaneous  and 

pulmonary  exhalation,  272 
Solar  plexus  of  sympathetic  nerve,  416 
Sounds,  of  heart,  235 
how  produced,  236 
vocal,  how  produced,  420 
destroyed  by  section  of  inferior  la- 
ryngeal nerves,  403 
of  spinal  accessory,  404 
Sounds,  acute  and  grave,  transmitted  by 

memljrana  tympani,  421 
Species,  mode  of  continuation,  429 
Spermatic  fluid,  458 

mixed  constitution  of,  462 
Spermatozoa,  458-459 
movements  of,  460 
formation  of,  461 
Spina  bifida,  543 
Spinal  accessory,  392 
sensibility  of,  393 

communication  of,  with  pneumogas- 
tric, 400 
Influence  of,  on  larynx,  404 
Spinal  column,  formation  of,  493,  543 
Spinal  cord,  319-340 

commissures  of,  320 
anterior  and  posterior  columns,  321 
origin  of  nerves  from,  319,  320 
sensibility  and  excitability  of,  343 
crossed  action  of,  344 
reflex  action  of,  348 
protective  action  of,  353 
influence  on  sphincters,  354 
effect  of  injury  to,  355 
on  respiration,  380 
formation  of,  in  embryo,  493,  543 
Spinal  nerves,  origin  of,  319,  321 
Spleen,  173 

Malpighian  bodies  of,  174 
extirpation  of,  176 
Spontaneous  generation,  429 


606 


INDEX. 


Starch,  47 

proportion  of,  iu  different  kinds  of 

food,  48 
varieties  of,  48 
reactions  of,  50 
action  of  saliva  on,  96 
digestion  of,  118 
Starfish,  nervous  system  of,  313 
St.  Martin,  case  of  gastric  fistula  in,  103 
Strabismus,  after  division  of  motor  oculi 
communis,  389 
of  motor  externus,  389 
Striated  bodies,  359 
Sublingual  gland,  secretion  of,  93-94 

nerve,  392 
Submaxillary  ganglion,  414 

gland,  secretion  of,  93-94 
Sudoriparous  glands,  271 
Sugar,  51 

varieties  of,  51 

composition  of,  52 

tests  for,  52 

fermentation  of,  52 

proportion  in  diflferent  kinds  of  food, 

54 
source  and  destination,  54 
discharged  by  urine  in  disease,  299 
Sugar  in  liver,  formation  of,  165 
percentage  of,  167 
produced  in  hepatic  tissue,  168 
from  glycogenic  matter,  169 
absorbed  by  hepatic  blood,  171 
decomposed  in  circulation,  171 
Sulphates,  alkaline,  in  urine,  296 
Sulphur  of  the  bile,  147 

not  discharged  with  the  feces,  161- 
162 
Swallowing,  100 

retarded  by  suppression  of  saliva,  99 
by  division  of  pneumogastic,  411 
Sympathetic  nerve,  414 
its  distribution,  415 
sensibility  and  excitability  of,  417 
influence  of,  on  special  senses,  418 
onpupil,  418,  419,  423 
on  nutrition  of  eyeball,  397-398 
on  nasal  passages,  420 
on  ear,  421 

on    temperature    of    particular 
parts,  421-422 
reflex  actions  of,  424 

Tadpole,  development  of,  494-495 

transformation  into  frog,  496 
Taenia,  438 

produced  by  metamorphosis  of  cys- 
ticercus,  440 

single  articulation  of,  443 
Tapeworm,  438 

mode  of  generation,  439 
Taste,  nerves  of,  398-399 

of  alimentary  substances,  developed 
by  cooking,  82 


Taurine,  147 
Tauro-cholate  of  soda,  146 

microscopic  characters  of,  144-145 
Tauro-cholic  acid,  147 
Tears,  273 

their  function,  274 
Teeth,  of  serpent,  89 
of  polar  bear,  90 
of  horse,  90 
of  man,  91 

first  and  second  sets  of,  590-591 
Temperature,  of  the  blood,  219 

of  diff'erent  species  of  animals,  220 
of  the  blood  in  diflferent  organs,  227 
elevation  of,  after  section  of  sympa- 
thetic nerve,  422 
Tensor  tympani,  action  of,  421 
Tests,  for  starch,  50 
for  sugar,  52 
for  bile,  150 
Pettenkofer's,  151 
Testicles,  461 

periodical  activity  of,  in  flsh,  433 
development  of,  558 
descent  of,  559 
Tetanus,  pathology  of,  350 
Thalami,  optic,  in  rabbit,  323 
in  man,  326 
function  of,  359. 
Thoracic  duct,  134 
Thoracic  respiration,  380 
Tongue,  motor  nerve  of,  392 

sensitive,  398-399 
Trichina  spiralis,  436 
Tricuspid    valve,    234.      See   Auriculo- 

ventricular. 
Triple  phosphate,  in  putrefying  urine, 

304 
Trommer's  test  for  sugar,  52 

interfered  with  by  gastric  juice,  111 
Tuber  annulare,  325 

efi'ect  of  destroying,  377 
action  of,  378 
Tubercula  quadrigemina,  322,  323,  373 
reflex  action  of,  374 
crossed  action  of,  375 
development  of,  540 
Tubules  of  uterine  mucous  membrane, 

517 
Tufts,  placental,  527 

Tunica  vaginalis  testis,  formation  of,  561 
Tympanum,  function  of,  in  hearing,  421 

Umbilical  cord,  formation  of,  533 

withering  and  separation  of,  590 
Umbilical  hernia,  548 
Umbilical  vesicle,  498 

in  human  embryo,  499 

in  chick,  506 

disappearance  of,  533 
Umbilical  vein,  formation  of,  570-577 

obliteration  of,  578 
Umbilicus,  abdominal,  494 


INDEX. 


607 


Umbilicus,  amniotic,  502 

decidual,  519 
Unilateral    mastication,    in    ruminating 

animals,  94 
Urate  of  soda,  288 

its  properties,  source,  daily  quantity, 
kc,  289 
Urates  of  potass  and  ammonia,  289 
Urachus,  549 
Urea,  284 

source  of,  285 

mode  of  obtaining,  285 

conversion   into   carbonate   of  am- 
monia, 285 

daily  quantity  of,  286 

diurnal  variations  in,  287 

decomposed  in  putrefaction  of  urine, 
302 
Uric  acid,  288,  296 
Urine,  290 

general  character  and  properties  of, 
291 

quantity  and  specific  gravity,  292 

diurnal  variations  of,  293 

composition  of,  294 

reactions,  295-296 

interference   with   Trommer's    test, 
297 

accidental  ingredients  of,  297 

acid  fermentation  of,  300-301 

alkaline  fermentation  of,  302 

final  decomposition  of,  304 
Urinary  bladder,  paralysis  and  inflam- 
mation of,  after  injury  to  spinal 
cord,  355 

formation  of,  in  embryo,  548 
Urosacine,  71 
Uterus,  of  lower  animals,  455 

of  human  female,  456 

mucous  membrane  of,  517 

changes  in,  after  impregnation,  518 

involution  of,  after  delivery,  537 

development  of,  in  foetus,  562 

position  of,  at  birth,  564 
Uterine  mucous  membrane,  516 

tubules  of,  517 

conversion  into  decidua,  519 

exfoliation  of,  at  the  time  of  delivery, 
535 

its  renovation,  536 

Valve,  Eustachian,  581-582 

of  foramen  ovale,  585 
Valves,  cardiac,  action  of,  234 

cause  of  heart's  sounds,  236 
Vasa  deferentia,  formation  of.  559-560 
Vapor,  watery,  exhalation  of,  39 

from  lungs,  207 

from  the  skin,  271 
Variation,  in  quantity  of  bile  in  differ- 
ent animals,  154-157 

in  production  of  liver-sugar,  171-172 

in  size  of  spleen,  173 


Variation,  in  rapidity  of  coagulation  of 
blood,  192 
in  size  of  glottis  in  respiration,  205 
in  exhalation  of  carbonic  acid,  214- 

216 
in  temperature  of  blood  in  different 

parts,  227 
in  composition  of  milk  during  lac- 
tation, 278 
in  quantity  of  urea,  286-287 
in  density  and  acidity  of  urine,  291 
-293 
Varieties  of  starch,  48 
of  sugar,  51 
of  fat,  54 

of  biliary  salts  in  diiferent  animals, 
158 
Vegetable  food,  necessary  to  man,  74 
Vegetables,  production  of  heat  in,  221 
absorption  of  carbonic  acid  and  ex- 
halation of  oxygen  by,  17,  225 
Vegetable  parasites,  434-435 
Vegetative  functions,  27 
Veins,  252 

al3Sorption  by,  131 
action  of  valves  in,  253 
motion  of  blood  through,  252-254 
rapidity  of  circulation  in,  254,  255 
omphalo-mesenteric,  567 
umbilical,  570 
vertebral,  573 
Vense  cavse,  formation  of,  574-575 

position  of,  in  foetus,  581 
Vena    azygos,    superior    and     inferior, 

formation  of,  575 
Venous  system,  development  of,  573 
Ventricles  of  heart,  single   in  fish  and 
reptiles,  230-231 
double   in  birds  and  mammalians, 

232 
situation  of,  233 

contraction  and  relaxation  of,  239 
elongation  during  contraction,  240 
muscular  fibres  of,  242 
Vernix  caseosa,  545 
Vertebrata,  nervous  system  of,  318 
Vertebrje,  formation  of,  493,  543 
Vesicles,  adipose,  58 
pulmonary,  200 
seminal,  462,  561 
Vesiculse  seminales,  462 

formation  of,  561 
Vicarious    secretion,    non-existence    of, 

266 
Vicarious  menstruation,  nature  of,  266 
Villi,  of  intestine,  129 
absorption  by,  130 
of  chorion,  512 
Vision,  ganglia  of,  322,  323,  326,  373 

nerves  of,  386 
Vital  phenomena,  their  nature  and  pecu- 
liarities, 22 
Vitellus,  447 


608 


INDEX. 


Vitellus,  segmentation  of,  489 

formation  of,  in  ovary  of  foetus,  564, 
565 
Vitelline  circulation,  566,  567 
Vitelline  membrane,  446 
Vitelline  spheres,  489 
Vocal  sounds,  how  produced,  402 
Voice,  formation  of,  in  larynx,  402 

lost,  after  division  of  spinal  acces- 
sory nerve,  403 
Volition,  seat  of,  in  tuber  annulare,  377 
Vomiting,    peculiar,    after    division    of 
pneumogastrics,  411 

Water,  as  a  proximate  principle,  37 

its  proportion  in  the  animal  tissues 

and  fluids,  38 
its  source,  38 

mode  of  discharge  from  the  body, 
39 
Weight  of  organs,  comparative,  in  newly 

born  infant  and  in  adult,  590 
White  globules  of  the  blood,  185 


White  globules  of  the  blood,  action  of 
acetic  acid  on,  186 
sluggish  movement  of,  in  circulation, 
257 
White   substance,   of   nervous    system, 
308 
of  Schwann,  308 
of  spinal  cord,  320-321 
of  brain,  insensible  and  inexcitable, 
360 
Withering  and  separation  of  umbilical 

cord,  after  birth,  590 
Wolffian  bodies,  556 
structure  of,  557 

atrophy  and  disappearance  of,  560 
vestiges  of,  in  adult  female,  563 
WvMAN,  Prof.  Jeffries,  on  cranial  nerves 
of  Rana  pipiens,  388 

Yellow  color,  of  urine  in  jaundice,  299 
of  corpus  luteum,  481 

Zona  pellucida,  446 


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worthy  a  continuance  of  the  very  remarkable  favor  which  it  has  hitherto  enjoyed.  The  rapid 
sale  of  Fifteen  large  editions,  and  the  constantly  increasing  demand,  show  that  it  is  regarded 
by  the  profession  as  the  standard  authority.  Stimulated  by  this  fact,  the  author  has  endeavored 
in  the  present  revision  to  introduce  whatever  might  be  necessary  "to  make  it  a  satisfactory 
and  desirable — if  not  indispensable — lexicon,  in  which  the  student  may  search  without  disap- 
pointment for  every  term  that  has  been  legitimated  in  the  nomenclature  of  the  science  "  To 
accomplish  this,  large  additions  have  been  found  requisite,  and  the  extent  of  the  author's  labors 
may  be  estimated  from  the  fact  that  about  Six  Thousand  subjects  and  terms  have  been  intro- 
duced throughout,  rendering  the  whole  number  of  definitions  about  Sixty  Thousand,  to  ac- 
commodate which,  the  number  of  pages  has  been  increased  by  nearly  a  hundred,  notwithstand- 
ing an  enlargement  in  the  size  of  the  page.  The  medical  press,  both  in  this  countrj^  and  in 
England,  has  pronounced  the  work  indispensable  to  all  medical  students  and  practitioners,  and 
the  present  improved  edition  will  not  lose  that  enviable  reputation. 

The  publishers  have  endeavored  to  render  the  mechanical  execution  worthy  of  a  volume  of 
such  universal  use  in  daily  reference.  The  greatest  care  has  been  exercised  to  obtain  the  typo- 
graphical accuracy  so  necessary  in  a  work  of  the  kind.  By  the  small  but  exceedingly  clear 
type  employed,  an  immense  amount  of  matter  is  condensed  in  its  thousand  ample  pages,  while 
the  binding  will  be  found  strong  and  durable.  With  all  thete  improvement*  and  enlargements, 
the  price  has  been  kept  at  the  former  very  moderate  rate,  placing  it  within  the  reacii  of  all. 


This  work,  the  appearance  of  the  fifteenth  edition 
of  which  it  has  become  our  duty  and  pleasure  to  an- 
nounce, is  perhaps  the  most  stupendous  monument 
of  labor  and  erudition  in  medical  literature.  One 
would  hardlj'  suppose  after  constant  use  of  the  pre- 
ceding; editions,  where  we  have  never  failed  to  find  a 
sufiSciently  full  explanation  of  every  medical  term, 
that  in  this  edition  "about  six  thousand  subjects  and 
terms  have  been  added"  with  a  careful  revision  and 
correction  of  the  entire  work.  It  is  only  necessary  to 
announce  the  advent  of  this  edition  to  make  it  occupy 
the  place  of  the  preceding  one  on  the  table  of  every 
medical  man.  as  it  is  without  doubt  the  best  and  most 
comprehensive  work  of  the  kind  which  has  ever  ap- 
peared.— Buffalo  Med.  Journ.,  Jan.  1S58. 

The  work  is  a  monument  of  patient  research,  skilful 
judgment,  and  vast  physical  labor,  that  will  perpetu- 
ate the  name  of  the  author  more  effectually  than  any 
possible  device  of  stone  or  metal.  Dr.  Dunglison  de- 
serves the  thanks  not  only  of  the  American  profession, 
but  of  the  whole  medical  world. — JVorth  Am.  Mtdico- 
Chir.  Review,  Jan.  1858. 

A  Medical  Dictionary  better  adapted  for  the  wants 
of  the  profession  than  any  other  with  which  we  are 
acquainted,  and  of  a  character  whicli  places  it  far 
above  comparison  and  competition. — American  Jour- 
nal of  the  Medical  Sciences,  Jan.  1858. 


AVe  need  only  say,  that  the  addition  of  6,000  new 
terms,  with  their  accompanying  definitions,  may  be 
said  to  constitute  a  new  woric  by  itself.  We  have  ex- 
amined the  Dictionary  attentively,  and  are  most  happy 
to  pronounce  it  unrivalled  of  its  kind.  The  erudition 
displayed,  and  the  extraordinary  industry  which  must 
have  been  demanded,  in  its  preparation  and  perfec- 
tion, redound  to  the  lasting  credit  of  its  author,  and 
have  furnished  us  with  a  volume  indispensable  at  the 
present  day,  to  all  who  would  find  themselves  au  ni- 
veau with  the  highest  standards  of  medical  informa- 
tion.—jBostore  Med.  and  Surg.  Journal,  Dec.  31, 1867. 

Good  lexicons  and  encyclopedic  works  generally,  are 
the  most  labor-saving  contrivances  which  literary  men 
enjoy:  and  the  labor  which  is  required  to  produce 
them  in  the  perfect  manner  of  this  example  is  some- 
thing appalling  to  contemplate.  The  author  tells  us 
in  his  preface  that  he  has  added  about  six  thousand 
terms  and  subjects  to  this  edition,  which,  before,  was 
considered  universally  as  the  best  work  of  the  kind  in 
any  language. — Silliman's  Journal,  March,  1858. 

A  very  perfect  work  of  the  kind,  undoubtedly  the 
most  perfect  in  the  English  language.— i/ed.  awd  Surg. 
Reporter,  Jan.  1858. 

The  most  complete  authority  on  the  subject  to  be 
found  in  any  language. — Va.  Med.  Journal,  Feb.  185  8. 


BLANCHARU    AND   LEA'S 


New  and  Improved  Edition— Just  Issued. 


XN  ANALYTICAL  COMPEIDIDM 

OF  THE  VARIOUS  BRANCHES  OF  MEDICAL  SCIENCE. 

£ov  tlje  ilse  arib  (£?famincition  of  Stubcnts. 

BY  JOHN  NEILL,  M.  R, 

StlKGEON  TO  THE  PENNSYLVANIA  HOSPITAL,  ETC., 
AND 

FRANCIS  GURNEY  SMITH,  M.  D., 

PROFESSOR  OF  INSTITUTES  OF  MEDICINE  IN  THE  PENNSYLVANIA  MEDICAL  COLLEGE,  ETC. 

A  NEW  EDITION,  REVISED  AND  IMPROVED, 
With  Three  Hnndred  and  Seventy-four  Illnstrations. 

/«  one,  very  large  and  handsome  royal  l2mo.  volume  of  vmrly  1000  pages,  strongly  honnd  in 
leather,  with  raised  bands.     $3. 

This  work  presents  a 
complete  and  systematic- 
outline  of  the  whole  range 
of  medical  science,  di- 
vided under  the  headings 
of  Anatomy,  Physiolo 
GY,  Surgery,  Midwife- 
ry, Chemistry,  Mate- 
ria Medica  and  The- 
rapeutics, and  Prac- 
tice or  Medicine. — 
Each  portion  is  thorough- 
ly and  appropriately  il- 
lustrated, rendering  tlie 
volume  one  of  the  cheap- 
est as  yet  placed  befure 
the  profession. 


Lateral  Operation  of  Lithotomy 


The  very  flattering  reception  which  has  been  accorded  to  this  work,  and  the  high  estimate 
placed  upon  it  by  the  profession,  as  evinced  by  the  constant  and  increasing  demand  which  has 
rapidly  exhausted  two  large  editions,  have  stimulated  the  authors  to  render  the  volume  in  its 
present  revision  more  worthy  of  the  success  which  has  attended  it.  It  has  accordingly  been 
thoroughly  examined,  and  such  errors  as  had  on  former  occasions  escaped  observation  have  been 
corrected,  and  whatever  additions  were  necessary  to  maintain  it  on  a  level  with  the  advance  of 
science  have  been  introduced.  The  extended  series  of  illustrations  has  been  still  further  in- 
creased and  much  improved,  while,  by  a  slight  enlargement  of  the  page,  these  various  additions 
have  been  incorporated  without  increasing  the  hulk  of  the  volume. 

The  work  is  therefore  again  presented  as  eminently  worthy  of  the  favor  with  which  it  has 
hitherto  been  received.  As  a  book  for  daily  reference  by  the  student  requiring  a  guide  to  his 
more  elaborate  text-books,  as  a  manual  for  preceptors  desiring  to  stimulate  their  students  by 
frequent  and  accurate  examination,  or  as  a  source  from  which  the  practitioners  of  older  date 
may  easily  and  cheaply  acquire  a  knowledge  of  the  changes  and  improvement  in  professional 
science,  its  reputation  is  permanently  established. 

The  Compend  of  Drs.  Neill  and  Smith  is  inoompara 
bly  the  most  valuable  Tvork  of  its  class  ever  published 
in  this  country.  Attempts  have  been  made  in  various- 
quarters  to  squeeze  Anatomy,  Physiolosiy,  Surgery,  the 
Practice  of  Medicine,  Obstetrics,  Materia  Medica,  and 
Chemistry  into  a  single  manual ;  but  the  operation 
has  signally  failed  in  the  hands  of  all  up  to  the  advent 
of  "  Neill  and  Smith's"  volume,  which  is  quite  a  mira- 
cle of  success.  The  outlines  of  the  whole  are  admirably 
drawn  and  illustrated,  and  the  authors  are  eminently 
entitled  to  the  grateful  consideration  of  the  student 
of  every  class. — N.  0.  Med.  and  Surg.  Joum.,  May,  1856. 


This  popular  favorite  with  the  student  is  so  well 
known  that  it  requires  no  more  at  the  hands  of  a 
medical  editor  than  the  annunciation  of  a  new  and 
improved  edition.  There  is  no  sort  of  comparison  be- 
tween this  work  and  any  other  on  a  similar  plan,  and 
for  a  similar  object. — Nashville  Journal,  of  Medicine, 
Sept.  1856. 


There  are  but  few  students  or  practitioners  of  medi- 
cine unacquainted  with  the  former  editions  of  this 
unassuming  though  highly  instructive  work.  The 
whole  science  of  medicine  appears  to  have  been  sifted, 
as  the  gold-bearing  sands  of  El  Dorado,  and  the  pre- 
cious facts  treasured  up  in  this  little  volume.  A  com- 
plete portable  library  so  condensed  that  the  student 
may  make  it  his  constant  pocket  companion. —  Western 
Lancet,  May,  1856. 

To  compress  the  whole  science  of  medicine  in  less 
than  1,000  pases  is  an  impossibility,  but  we  think  that 
the  book  before  us  Approaches  as  near  to  it  as  is  possi- 
ble. Altogether,  it  is  the  best  of  its  class,  and  has  met 
with  a  deserved  success.  As  an  elementary  text-book 
for  students,  it  has  been  useful,  and  will  continue  to 
be  employed  in  the  examination  of  private  classes, 
whilst  it  will  often  be  referred  to  by  the  country  prac- 
titioner.— Va.  Med.  Journal,  May,  1856. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 
NEW  AND  MUCH  ENLARGED  EDITION— (Just  Issued.) 


A  MANUAL  OF  EXAMmATIONS 

UPON 

ANATOMY,  PHYSIOLOGY,  SURGERY,  PRACTICE  OF  MEDICINE, 
CHEMISTRY,  OBSTETRICS,  MATERIA  MEDICA,  PHAR- 
MACY, AND  THERAPEUTICS: 

TO  WHICH  IS  ADDED  A  MEDICAL  FORMULARY. 

BY  J.  L.  LUDLOW,  M.  D. 

A  new  Edition,  thoroughly  modified,  and  greatly  extended  and  enlarged. 

With  three  hundred  and  seventy  wood  engravings, 


1)1  one  large  and  handsome  royal  VZtno.  vol.  of  over  S^Q 

closely  printed  pages,  strongly  bound  in  leather., 

price  S2  50. 


Crura  Cerebri,  ij-c. 


Ampulalion  of  Hand. 


The  great  popularity  which  this  volume  has  always  enjoyed,  has  stimulated  the  author  in 
his  revision  to  render  "it  in  every  respect  worthy  of  the  confidence  of  the  profession,  giving  rise 
to  the  delay  which  has  caused  it  to  remain  out  of  print  for  so  long  a  time  Every  portion  has 
been  sedulously  examined,  and  the  most  recent  observations  and  investigations  introduced, 
rendering  it  an  accurate  resume  of  the  most  improve!  condition  of  medi^^al  science.  A  con- 
siderable portion  has  been  rewritten,  and  entire  sections  on  Physiology  and  Organic  Chemistry 
have  been  added,  while  a  very  complete  series  of  illustrations  has  been  introduced,  elucidating 
the  text  wherever  such  assistance  appeared  necessary  or  desirable.  Notwithstanding  an  en- 
largement of  the  page,  these  improvements  have  increased  the  size  of  the  volume  to  over  eight 
hundred  pages,  and  with  the  greatly  improved  style  of  mechanical  execution,  it  may  in  almost 
every  respect  Ise  regarded  rather  as  a  new  work  than  a  new  edition. 

The  arrangement  of  the  volume  in  the  form  of  question  and  answer  renders  it  especially  suit- 
able for  the  office  examination  of  students,  and  for  those  preparing  for  graduation. 


We  would  recommend  this  book  as  one  of  the  best 
of  its  kind,  and  to  every  right-minded  student  a  most 
valuable  aid  in  acquiring  the  Facts  of  Medical  Science. 
— South.  Med.  and  Surg.  Journ.,  Nov.  1S57. 

In  the  main,  we  regard  his  work  as  well  adapted  for 
its  professed  object,  and  that  the  author's  claims  are 
valid.  Abundant  illustrations  of  the  text  are  fur- 
nished by  means  of  wood  cuts,  well  executed;  a  de- 
cided advantage  and  help  to  the  student. — Penin  Jour. 
of  Med;  Aug.  1857. 

For  the  purpose  for  which  it  is  intended,  we  do  not 


see  but  Dr  Ludlow's  work  is  as  good  as  any  other  of 
the  kind.  The  peculiarity  which  distinguishes  it  from 
some  others  of  the  same  class,  consists  in  the  form  of 
question  and  answer  in  which  it  is  written.  We  com- 
mend it  to  the  notice  of  the  student  who  feels  that  he 
must  rely  on  such  a  work  before  being  confidentially 
closeted  with  his  friends,  the  professors,  previous  to  a 
final  departure. — A^.  J.  Med.  Reporter,  Aug.  1857. 

The  illustrations  are  good ;  and  the  system  of  ques- 
tions and  answers  are  as  well  arranged  as  the  stu- 
dent seeking  this  kind  of  help  will  probably  desire. — 
Charleston  Med.  Jour.,  July,  1857. 


BLANCHARD    AND    LEA'S 


New  and  Enlarged  Edition— Just  Issued. 

A  DICTIONARY  OF  TERMS  USED  IN  MEDICINE, 

AND  THE   COLLATERAL   SCIENCES. 

BY  RICHARD  D.  HOBLYN. 

A  NEW  AMERICAN  FROM  THE  LAST  LONDON  EDITION. 

Revised,  with  numerous  Additions, 

BY  ISAAC  HAYS,  M.  D., 

Editor  of  the  American  Journal  of  the  Medical  Sciences. 

In  one  large  royal  Vlmo.  volume  £>/522  closely  printed  douhle-cohcmn  pages,  leather.  %\  50. 

In  this  volume  the  object  of  the  author  and  editor  has  been  to  produce  a  work  which,  at  an 
exceedingly  moderate  price,  and  in  a  portable  and  convenient  form,  should  prcf^ent  all  the  assist- 
ance requisite  to  the  medical  student  and  ordinary  scientific  reader.  All  obsolete  terms  have 
been  carefully  excluded,  and  it  will  be  found  a  complete  and  concise  manual  of  definitions,  em- 
bodying the  terms  employed  in  medicine  and  its  allied  sciences  in  their  present  advanced  condi- 
tion. By  the  employment  of  a  small  but  clear  type,  the  amount  of  an  ordinary  octavo  volume 
has  been  condensed  into  its  pages. 


If  the 'frequency  with  which  we  have  referred  to 
this  -volume  since  its  reception  from  the  publisher, 
two  or  three  weeks  ago,  tie  any  criterion  for  the  future, 
the  binding  will  soon  have  to  be  renewed,  even  with 
careful  handling.  We  find  that  Dr.  Hays  has  done 
the  profession  great  service  by  his  careful  and  indus- 
trious labors.  The  Dictionary  has  thus  become  emi- 
nently suited  to  our  medical  brethren  in  this  country. 
The  additions  by  Dr.  Hays  are  in  brackets,  and  we 
believe  there  is  not  a  single  page  but  bears  these  in- 
signia; in  every  instance  which  we  have  thus  far 
noticed,  the  additions  are  really  needed  and  exceed- 
ingly valuable.  We  heartily  commend  the  work  to 
alfwho  wish  to  be  au  courant  in  medical  terminology. 
— Boston  Med.  and  Surg.  Journal. 


To  supply  the  want  of  the  medical  reader  arising 
from  this  cause,  we  know  of  no  dictionary  better  ar- 
ranged and  adapted  than  the  one  bearing  the  above 
title.  It  is  not  encumbered  with  the  ob.solete  terms 
of  a  by-gone  age,  but  it  contains  all  that  are  now  in 
use;  emliracing  every  department  of  medical  science 
down  to  the  very  latest  date.  The  volume  is  of  a  con- 
venient size  to  be  used  by  the  medical  student,  and 
yet  large  enough  to  make  a  respectable  appearance  in 
the  library  of  a  physician. —  yVesta-n  Lancet. 

Hoblyn's  Dictionary  has  long-been  a  favorite  with 
us.  It  is  the  best  book  of  definitions  we  have,  and 
ought  always  to  be  upon  the  studeat'a  table. —  South- 
ern Med.  mid  Surg.  Journal. 


WILSON'S  DISSECTOR— New  Edition,  just  issued. 

THE  DISSECTOR'S  MANUAL 

OF  PRACTICAL  AND  SURGICAL  ANATOMY. 

BY  ERASMUS  WILSOX,  F.  R.  S., 

Author  of  "A  System  of  Human  Anatomy." 

Third  American  from  the 
last  and  Revised  Lon- 
don Edition. 

ILLUSTR.^TED  WITH 

144  Engravings  on  Wood. 

EDITED  BY 

WILLIAM  HUNT.  M.D., 

Demonstrator  of  Anatomy  in 
the  University  of  Penn'a 

In  one  large  and  handsome 

royal  12tno.  volume  of 

58-4  pages. 

Bound  in  leather,  $2, 

The  modifications  and  additions  which 
this  work  has  received  in  again  passing 
through  the  hands  of  the  author  are 
sufficiently  indicated  by  the  fact  that 
the  present  edition  contains  nearly  one- 
half  more  matter  than  the  preceding, 
while  the  series  of  illustrations  ha* 
been  increased  in  extent  and  greatly 
improved  in  character.  By  the  em- 
ployment of  a  smaller  type,  these  addi- 
tions have  been  accommodated  with- 
out a  correspondnig  enlargement  in 
the  size  and  price  of  the  volume,  and 
it  is  again  presented  as  fully  worthy  a 
continuance  of  the  favor  which  it  has 
heretofore  enjoyed  as  a  sound  practical 
guide  to  the  study  of  anatomy. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


A  NE-W  AMERICAN  DISSECTOR— (Just  Issued). 

THE  PEACTIOAL  ANATOMIST; 

OR, 

THE    STUDENT'S    GUIDE    IN   THE    DISSECTING-ROOM. 
BY  J.  M.  ALLEN,  M.  D., 

Late  Professor  of  Anatomy  in  the  Pennsylvania  Medical  College. 

SMitlj  26*6^  Illustrations. 

In  07ie  large  and  very  hatidsomi',  royal  12mo.  volume  of  632  pages,  leather,  $2  25. 

The  very  large  number  of  elaborate  illusira- 
lions  with  which  this  woric  abounds,  serves  to 
render  the  verbal  details  easy  of  comprehen- 
sion, showing  the  student  what  to  examine, 
and  where  and  how  to  look  for  it,  while  the 
long  experience  of  the  author  as  a  teacher  of 
anatomy,  has  given  him  a  familiarity  with  the 
wants  of  students,  and  has  shown  him  the 
best  modes  of  obviating  or  relieving  the  difli- 
cullies  which  present  themselves  in  the  pro- 
gress of  dissection.  As  adapted  to  the  course 
pursued  in  our  colleges,  and  as  containing  am- 
ple practical  directions  and  instructions,  in  ad- 
dition to  the  anatomical  details  presented,  it, 
therefore,  possesses  claims  to  the  immediate 
attention  of  teachers  and  students. 

It  is  a  very  convenient  manual,  and  by  its  ar- 
rangement, is  well  adapted  to  the  study  of  practical 
anatomy. — N'.  Y.  Journ.  of  Medicine. 

We  think  it  admirably  arranged  for  rendering  aid 
to  the  student  in  prosecuting  dissections.  Its  illus- 
trations are  generally  accurately  drawn  and  highly 
useful.  It  will,  doubtless,  rank  among  the  best 
guides  in  the  study  of  practical  anatomy  that  are 
now  before  the  profession. — N.  W.  Med.  and  Surg. 
Journal,  Jan.  1857. 

We  are  greatly  pleased  with  Prof  Allen's  little 
work.  We  handed  our  copy  to  a  friend,  who  is  more 
particularly  engaged  in  Practical  Anatomy,  for  his 
careful  examination  and  opinion ;  he  reports  it  "  the 
very  best  dissector  yet  produced."  The  arrangement 
is  clear,  concise,  and  convenient;  its  size  is  satisfac- 
tory— full  enough  for  all  the  purposes  of  the  dissect- 

ins-rorm,  and  yet,  not  prolix  or  bulky.    It  is  beautifully  illustrated— perhaps  much  the  most  so  of  any 

dissector  yet  published. — Cincinnati  Med.  Observer. 


Arteries  in  the  Groin. 


SPECIAL  ANATOMY  AND  HISTOLOGY 


BY  WILLIAM  E.  HORNER,  M.  D , 

Late  Professor  of  Anatomy  in  the  University  of  Pennsylvania 

3£i5tlt  anij  EmproiitlJ  B&ition. 

I?i  two  large  and  handsome  octavo  volumes  of  over  one 
thousand  pages, 

With  more  than  300  beautiful  Illustrations. 

Extra  Cloth,  $6. 

This  work  has  so  long  occupied  the  position  ot 
a  standard  text-book  and  work  of  reference  among 
anatomists,  that  the  present  edition,  fully  revised 
and  thoroughly  brought  up  by  the  author  shortly 
before  his  death,  cannot  fail  to  maintain  its  distin- 
guished reputation. 


Os  Femoris  macerated  in  acid. 


BLANCHAUD    AND    LEA'S 


THE    STUDENT'S    TEXT-BOOK    OF    ANATOMY. 

New  and  much  enlarged  edition — Just  Ready  (1858). 


In  one  large 

and  exquisitely  printed 

octavo  Yolume, 

■with 

three  hundred  and  ninety-seven 

beautiful 

engravings  on  wood, 

and 


more  than  600  large  pages. 

Price,  in  leather, 

$3  25. 


Saphenous  opening  m  the  Fascia  Lata. 

A  SYSTEM  OF  HUMAN  ANATOMY. 

GENERAL   AND    SPECIAL. 

BY  ERASMUS  WILSON,  F.  R.  S, 

Author  of  "  The  Dissector's  Manual,"  "  A  Treatise  on  Diseases  of  the  Skin,"  &c. 

A  New  and  Revised  American,  from  the  last  and  enlarged  English  Edition. 

Edited  by  W.  H.  GOBRECHT,  M.  P., 

Professor  of  Anatomy  in  the  Philadelphia  College  of  Medicine,  &c. 

The  publishers  trust  that  the  well-earned  reputation  so  long 
enjoyed  by  this  work  will  be  more  than  maintained  by  the  pre- 
sent edition.  Besides  a  very  thorough  revision  by  the  author, 
it  has  been  most  carefully  examined  by  the  editor,  and  the 
efforts  of  both  have  been  directed  to  introducing  everything 
which  increased  experience  in  its  use  has  suggested  as  desira- 
ble to  render  it  a  complete  text- book  for  those  seeking  to  obtain 
or  to  renew  an  acquamtance  with  Human  Anatomy.  The 
amount  of  additions  which  it  has  thus  received  may  be  esti- 
mated from  the  fact  that  the  present  edition  contains  over  one- 
fourth  more  matter  than  the  last,  rendering  a  smaller  type  and 
an  enlarged  page  requisite  to  keep  the  volume  within  a  con- 
venient size.  The  author  has  not  only  thus  added  largely  to 
the  work,  but  he  has  also  made  alterations  throughout,  where- 
ver there  appeared  the  opportunity  of  improving  the  arrange- 
ment or  style,  so  as  to  present  every  fact  in  its  most  appropri- 
ate manner,  and  to  render  the  whole  as  clear  and  intelligible 
as  possible.  The  editor  has  exercised  the  utmost  caution  to  obtain  eniire  accuracy  in  the  text, 
and  has  largely  increased  the  number  of  illustrations,  of  which  there  are  about  one  hundred  and 
fifty  more  in  this  edition  than  in  the  last,  thus  bringing  distinctly  before  the  eye  of  the  student 
everything  of  interest  or  importance. 

The  publishers  have  felt  that  neither  care  nor  expense  should  be  spared  to  render  the  external 
finish  of  the  volume  worthy  of  the  universal  favor  with  which  it  has  been  received  by  the  Ame- 
rican profession,  and  they  have  endeavored,  consequently,  to  produce  in  its  mechanical  execu- 
tion, an  improvement  corresponding  with  that  which  the  text  has  enjoyed.  It  will  therefore  be 
found  one  of  the  handsomest  specimens  of  typography  as  yet  produced  in  this  country,  and  in 
all  respects  suited  to  the  office  table  of  the  practitioner,  notwithstanding  the  exceedingly  low 
price  at  which  it  has  been  placed. 


Portion  of  one  of  Peyer''s  Glands. 


It  is  therefore  at  the  expense  of  some  struggle  with 
our  predilections  that  we  find  ourselves  called  upon 
to  recognize  the  merits  of  a  successor  to  our  earlier 
companion  and  guide.  The  struggle  over,  we  are  con- 
strainea  to  declare  that  the  edition  of  1858  is  a  vast 
improvement  upon  all  others.  This  is,  in  one  sen- 
tence, the  best  edition  of  the  best  teaching  anatomy 
now  extant. — Nashville  Mrmthly  Record,  Nov.  '58. 

The  great  practical  value  of  Wilson's  Anatomy,  as  a 


manual  for  the  student,  the  practitioner,  and  for  all 
who  desire  to  become  acquainted  with  the  subject,  ia 
too  well  attested  by  the  unprecedented  success  of  the 
work,  and  the  universal  verdict  in  its  favor,  to  render 
recommendation  necessary.  We  have  ever  commend- 
ed Wilson's  Anatomy,  without  hesitation  or  reserve, 
to  students  of  medicine,  and  the  present  edition  only 
increases  our  approbation. — Southern  Med.  and  Surg. 
Journal,  Nov.  1858. 


MEDICAL   AND    SCIENTIFIC    PUBLICATIONS 


NEW  AND  MAGNIFICENT  ANATOMICAL  TEXT-BOOK— (Now  Ready.) 

ANATOMY,  DESCRIPTIVE  AND  SURGICAL. 

BY  HENRY  GRAY,  P.  K.  S., 

Lecturer  on  Anatomy  at  St.  George's  Hospital,  Loudon,  &c. 

The  Drawings  by  H.  V.  CARTER,  M.  D., 

Late  Demonstrator  of  Anatomy  at  St.  George's  Hospital. 

THE  DISSECTIONS  JOINTLY  BY  THE  AUTHOR  AND  DR.  CARTER. 

In  07ie  splendid  imperial  octavo  volume  of  about  800  very  large  pages,  with  363  large  and  elabo- 
rate engravings  on  wood.     Price  in,  extra  cloth,  $6  25;  in  leather,  raised  bands,  $7. 

The  author  has  endeavored  in  this  work  to  cover  a  more  extended  range  of  subjects  than  is 
customary  in  the  ordinary  text-books,  by  giving  not  only  the  details  necessary  for  the  student, 
but  also  the  application  of  those  details  in  the  practice  of  medicine  and  surgery,  thus  rendering 
it  not  only  a  guide  for  the  learner,  but  an  admirable  work  of  reference  for  the  active  practitioner. 
The  engravings  form  a  special  feature  in  the  work,  many  of  them  being  the  size  of  nature, 
nearly  all  original,  and  having  the  names  of  the  various  parts  printed  on  the  body  of  the  cut,  in 
place  of  figures  of  reference  with  descriptions  at  the  foot.  They  thus  form  a  complete  and 
splendid  series,  which  will  greatly  assist  the  student  in  obtaining  a  clear  idt  a  of  Anatomy,  and 
will  also  serve  to  refresh  the  memory  of  those  who  may  find  in  the  exigencies  of  practice  the 
necessity  of  recalling  the  details  of  the  dissecting-room;  while,  combining  as  it  does  a  complete 
Anatomical  Atlas  with  a  thorough  treatise  on  descriptive,  practical,  and  applied  anatomy,  the 
work  will  be  found  of  essential  service  to  physicians  who  receive  students  in  their  offices,  assist- 
ing both  teacher  and  pupil  in  laying  the  groundwork  of  a  thorough  medical  education. 

*^*  The  large  size  of  many  of  the  illustrations  prevents  the  selection  of  a  favorable  average 
specimen.  A  small  one,  however,  is  inserted  to  show  the  manner  in  which  the  lettering  ac- 
companies the  cuts.  It  will  be  observed  that  the  attachments  of  the  muscles  are  indicated  by 
dotted  lines. 


Occipital  Bone — outer  surface. 


As  a  full,  systematic,  and  advanced  treatise  on 
anatomy,  combining  the  various  merits  of  the  vol- 
umes of  many  countries,  scientifically  excellent, 
and  adapted  to  all  the  ■wants  of  the  student,  we  are 
not  acquainted  with  any  work  in  any  language 
which  can  take  equal  rank  with  the  one  before  us. — 
London  Lancet,  Sept.  11,  ISoS. 

Mr.  Gray's  book,  in  excellency  of  arrangement 
and  completeness  of  execution,  exceeds  any  work 


on  anatomy  hitherto  published  in  the  English  lan- 
guage, afi'ording  a  complete  view  of  the  structure  of 
the  human  body,  with  especial  reference  to  practi- 
cal surgery.  Thus  the  volume  constitutes  a  perfect 
book  of  reference  for  the  practitioner,  demanding  a 
place  in  even  the  most  limited  library  of  the  phy- 
sician or  surgeon,  and  a  work  of  necessity  for  the 
student  to  fix  in  his  mind  what  he. has  learned  by 
the  dissecting  knife  from  the  book  of  nature. — The 
Dublin  Qvxirterly  Journal  of  Med.  Sei.,  JNov.  1S58. 


10 


BLAN  CHARD    AND    LEA'S 


A   LIBRARY  ON   HUMAN   ANATOMY. 


HUMAli  AXiTOMY, 


BY  JONES  QUAIN,  M.  D. 


EDITED  BY 


RICHARD  QUAIN,  M.  D., 


WM.  SHARPEY,  M.D.,  F.R.S., 

Professors  of  Anatomy  and  Physiology 
in  University  College,  London. 


View  of  the  Left  Nasal  Fossa. 


jFtrst  fCmwuan,  from  Hi  jfiitl  ^Lonbon  JEiilioir.  , 

Edited  by  JOSEPH  LEIDY,  M.  D., 

Professor  of  Anatomy  in  the  University  of  Pennsylvania. 

Li  two  large  arid  Jiandsome  octavo  volumes,  containing  thirteen  hundred  pages,  and  five  hun- 
dred and  eleven  beautiful  engravings  on  wood,  bound  in  leather.     Price  %%. 


It  is  indeed  a  work  calculated  to  make  an  era  in  ana- 
tomical study,  by  placing  before  the  student  every  de- 
partment of  his  science,  with  a  view  to  the  relative  im- 
portance of  each;  and  so  skilfully  have  the  different 
parts  been  interwoven, that  no  one  who  makes  this  work 
the  basis  of  his  studies,  will  hereafter  have  any  excuse 
for  neglecting  or  undervaluing  any  important  parti- 
culars connected  with  the  structure  of  the  human 
frame;  and  whether  the  bias  of  his  mind  lead  him  in 
a  more  especial  manner  to  surgery,  physic,  or  physio- 
logy, he  will  find  here  a  work  at  once  so  comprehen- 
sive and  practical  as  to  defend  him  from  exclusiveness 
on  the  one  hand,  and  pedantry  on  the  other. — Monthly 
Journal  and  Retrospect  of  the  Med.  Sciences. 


TVe  have  no  hesitation  in  recommending  this  treatise 
on  anatomy  as  the  most  complete  on  that  subject  in 
the  English  language:  and  the  only  one.  perhaps,  in 
any  language,  which  brings  the  state  of  knowledge 
forward  to  the  most  recent  discoveries. — The  Edinburgh 
Med.  and  Surg.  Journal. 

Admirably  calculated  to  fulfil  the  object  for  which 
it  is  intended. — Prminciol  Medical  Journal. 

The  most  complete  Treatise  on  Anatomy  in  the 
English  language. — Edinburgh  Medical  Journal. 

There  is  no  work  in  the  English  language  to  be  pre- 
ferred to  Dr.  Quain's  Elements  of  Anatomy. — London 
Journal  of  Medicine. 


CARPENTER'S  MANUAL  OE  PHYSIOLOGY. 


ELEMENTS 

OF 

physiology: 

INCLUDING 

PHYSIOLOGICM  ANATOMY. 

BY 

AV.  B.  Carpenter,  M.D.,F.R.S. 

AUTHOR  OF 

"  Human  Physiology,"  "  Compara- 
tive Physiology,"  &c. 

r\    Second  American,  from  a  late 
J'-^'  and  Revised  London  edition. 

-^  '    With  190  Illustrations. 

In  one  handsome  octavo  volume  of 
566  pages,  leather,  $3. 


Distribution  of  Olfactory  Nerve. 


MEDICAL   AND  SCIENTIFIC    PUBLICATIONS. 
SMITH  AND  HORNER'S  ANATOMICAL  ATLAS. 


ANATOMICAL  ATLAS, 

ILLUSTRATIYE  OF  THE  STRUGTUEE 
OF  THE  HUMAN  BODY. 


Nerves  of  Ampulla  of  the  Ear. 

By  henry  H.  smith,  M.  D., 

Professor  of  Surgery  in  the  University  of  Pennsylvania, 
UNDER  THE  SUPERVISION  OF 

WM.  E.  HORNER,  M.  D., 

Late  Professor  of  Anatomy  in  the  University  of  Pennsylvania. 

With  about  Six  Hundred  and  Fifty  exquisite  Illustrations  on  Wool. 
In  one  imperial  octavo  volume,  extra  cloth.     Price  S3. 


The  great  advantages  possessed  by  vrood- 
engraving  for  scientific  illustration,  in  the 
clearness  and  distinctness  of  its  minute  details, 
are  fully  shown  in  this  work,  containing  as  it 
does,  in  the  compass  of  a  single  convenient 
volume,  the  general  and  special  anatomy  of  all 
the  component  parts  of  the  body.  Commencing 
with  the  Bones  and  Ligaments,  iffollows  with 
the  Muscular  and  Dermoid  Systems,  the  Or- 
gans of  Digestion  and  Generation,  Respiration 
and  Ciiculation,  and  concludes  with  the  Nerv- 
ous System  and  the  Senses.  Not  only  is  every 
separate  organ  and  portion  of  the  human  frame 
thus  biought  distinctly  and  separately  before 
the  eye  o(  the  student,  but  he  is  also  presented 
with  llie  results  of  the  recent  microscopical 
investigations  into  the  minute  anatomy  of  the 
various  tissues ;  while  the  plan  adopted,  giving 
the  plate  and  references  on  the  same  page,  en- 
ables him  to  obtain  a  more  definite  impression 
of  the  objects,  by  avoiding  the  annoyance  and 
interruption  of  turning  backwards  and  for- 
wards. As  a  specimen  of  art,  nothing  superior 
to  it  has  yet  been  produced,  while  the  exceed- 
ingly low  rate  at  which  it  is  offered,  places  it 
within  the  reach  of  ever}''  member  of  the  pro- 
fession. To  country  practitioners  and  students 
it  will  be  found  especially  useful,  as  supplying 
in  a  great  measure  the  place  of  skeletons  and 
subjects. 

The  plan  of  this  Atlas  is  admirable,  and  its  execu- 
tion superior  to  anything  of  the  kind  before  published 
in  this  country.  It  is  a  real  labor-saving  affair,  and 
we  regard  its  publication  as  the  greatest  boon  that 
could  be  conferred  on  the  student  of  anatomy.  It  "ivill 
be  equally  valuable  to  the  practitioner,  by  affording 
him  an  easy  means  of  recalling  the  details  learned  in 
the  dissecting-room,  and  which  are  soon  forgotten. — 
American  Medical  Journal. 


Deep  stated  Muscles  of  the  Hip. 


THE  PRINCIPAL  FORMS  OF  THE  SKELETON  AND  OF  THE  TEETH. 
By  Professor  R.  Owen,  F.  R.  S  ,  Author  of  "Lectures  on  Comparative  Anatomy,"  &c. 
With  seventy-six  beautiful  illustrations,  fn  one  handsome  volume,  royal  12mo.,  of  three 
hundred  and  thirty  pages,  extra  cloth,  $1  25. 


12 


BLANC  HARD   AND   LEA'S 


Just  Issued. 


IN  ITS  RELATIONS  TO 

DESCRIPTIYE  ANATOMY,  PHYSIOLOGY,  AND  PATHOLOGY. 

WITH   FOUR   HUNDRED   AND   THIRTY-EIGHT  ILLUSTRATIONS   ON   WOOD. 

BY  E.  R.  PEASLEE,  M.  D., 

Professor  of  Physiology  and  Pathology  in  the  New  York  Medical  College,  etc. 


.^v^^Tf^ 


^\^^ 


C-J 


.--L 

- 

In  one 

.-c 

beautifully  printed 
octavo  volume 
of  616  pages. 

Price, 

^^ 

-A 

in  leather. 

) 

$3  75. 

'7 

Insertion  of  Tendo  Achillis  hito  Calcaneutn. 

It  embraces  a  library  upon  the  topics  discussed  within 
itself,  and  is  just  what  the  teacher  and  learner  need  Ano- 
ther advantage,  by  no  means  to  be  overlooked,  everything 
of  real  value  in  the  wide  range  which  it  embraces,  is  with 
great  skill  compressed  into  an  <octavo  volume  of  but  little 
more  than  six  hundred  pages.  We  have  not  only  the  whole 
subject  of  Histology,  interesting  in  itself,  ably  and  fully  dis- 
cussed, but  what  is  of  infinitely  greater  interest  to  the  stu- 
dent, because  of  greater  practical  value,  are  its  relations  to 
Anatomy,  Physiology,  and  Pathology,  which  are  here  fully 
and  satisfactorily  set  forth.  These  great  supporting  branches 
of  practical  medicine  are  thus  linked  together,  and  white 
establishing  and  illustrating  each  other,  are  interwoven  into 
a  harmonious  whole.  We  commend  the  work  to  students 
and  physicians  generally. — Nashville  Journ.  of  Medicine  and 
Surgery,  Dec.  1857. 

It  far  surpasses  our  expectation.  We  never  conceived  the 
possibility  of  compressing  so  much  valuable  information  into 
so  compact  a  form.  We  will  not  consume  space  with  com- 
mendations. We  receive  this  contribution  to  physiological 
science  "not  with  vain  thanks,  but  with  acceptance  boun- 
teous." We  have  already  paid  it  the  practical  compliment 
of  making  abundant  use  of  it  in  the  preparation  of  our  lec- 
tures, and  also  of  recommending  its  further  perusal  most 
cordially  to  our  alumni ;  a  recommendation  which  we  now 
extend  to  our  readers. — Memphis  Med.  Recorder,  Jan.  1858. 

We  would  recommend  it  to  the  medical  student  and  prac- 
titioner, as  containing  a  summary  of  all  that  is  known  of  the 
important  subjects  which  it  treats;  of  all  that  is  contained 
in  the  great  works  of  Simon  and  Lehmann,  and  the  organic 
chemists  in  general.  Master  this  one  vohime,  we  would  say 
to  the  medical  student  and  practitioner — master  this 
book  and  you  know  all  that  is  known  of  the  great  fun- 
damental principles  of  medicine,  and  we  have  no  hesi- 
tation in  saying  that  it  is  an  honor  to  the  American 
medical  profession  that  one  of  its  members  should  have 
produced  it. — St.  Louis  Med.  and  Surg.  Jour.,  Mar.,  '58. 


Ceinfnl  and  Detitine  at  root  of  Tooth. 


This  work  treats  of  the  foundation  of  things,  and 
deserves  a  careful  perusal  by  all  those  who  wish  to  be 
respectably  informed  in  their  profession. — Ohio  Med. 
and  Surg.  Journal,  May,  1858. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


13 


New  and  Enlarged  Edition — Just  Issued. 


Containing  nearly 
fifteen  hundred  large  pages, 

with 

five  hundred  and  thirty-two 

handsome  illustrations 

on  wood. 


,<i     I 


Eighth  Edition, 

Revised,  Modified, 

and  Enlarged. 

In  two  large  and  handsomely 

printed  octavo  volumes, 

leather,  price  $7. 


HUMAN   PHYSIOLOGY. 

BY  KOBLEY  DUN6LIS0N,  M.  D.,LL.D., 

Professor  of  Institutes  of  Medicine  in  the  Jefferson  Medical  College,  Philadelphia. 

[n  revising  this  work  for  its  eighth  appearance,  the  an-  t 

tnor  has  spared  no  labor  to  render  it  worthy  a  continuance 
of  the  very  great  favor  which  has  been  extended  to  it  by 
the  profession.  The  whole  contents  have  been  rearranged, 
and  to  a  great  extent  remodelled  ;  the  investigations  which 
of  late  years  have  been  so  numerous  and  so  important, 
have  been  carefully  examined  and  incorporated,  and  the 
work  in  every  respect  has  been  brought  up  to  a  level  with 
the  present  state  of  the  subject.  The  object  of  the  author 
has  been  to  render  it  a  concise  but  comprehensive  treatise, 
containing  the  whole  body  of  physiological  science,  to 
which  the  student  and  man  of  science  can  at  all  times  refer 
with  the  certainty  of  finding  whatever  they  are  in  search 
of,  fully  presented  in  all  its  aspects  ;  and  on  no  former  edi- 
tion has  the  author  bestowed  more  labor  to  secure  this 
result 

A  similar  improvement  will  be  found  in  the  typographic- 
al execution  of  the  volumes,  which,  in  this  respect,  are  su- 
perior to  their  predecessors.  A  large  number  of  additional 
■wood-cuts  have  been  introduced,  and  the  series  of  illustra- 
tions has  been  greatly  modified  by  the  substitution  of  many 
new  ones  for  such  as  were  not  deemed  satisfactory.  By 
an  enlargement  of  the  page,  these  very  considerable  addi- 
tions have  been  accommodated  without  increasing  the  size 
of  the  volumes  to  an  extent  to  render  them  unwieldy. 


That  he  has  succeeded,  most  admirably  succeeded  in  his  purpose, 
is  apparent  from  the  appearance  of  an  eighth  edition,  and  well  may 
he  remark  iu  his  preface  that  "  the  reception  which  his  undertak- 
ings have  met  with  has  abundantly  satisfied  him  that  his  labors 
have  been  far  from  fruitless."  It  is  now  the  great  encyclopaedia  on 
the  subject,  and  worthy  of  a  place  in  every  physician's  library. — 
Western  Lancet. 


Cortical  Substance  of  Kidney . 


In  preparing  the  present  edition,  "no  pains  have 
been  spared  to  make  the  work  a  complete  expression 
of  the  science  of  the  day."  This  statement  our  own 
examination  of  the  work  enables  us  to  confirm ;  every 
page  of  it  testifying  to  the  author's  industry  in  cull- 
ing from  various  quarters  and  sources  all  that  was 
valuable  in  the  physiological  contributions  to  science 
of  the  last  few  years.  The  careful  and  scrutinizing 
spirit  exhibited  by  the  writer  when  investigating 
mooted  questions,  the  extensive  information  he  pos- 
sesses of  general  science  in  almost  every  department, 
and  the  clear  and  happy  style  in  which  he  presents 
his  views,  render  his  Physiology  one  of  the  most  re- 
liable and  attractive  works  in  our  language.  To  the 
practitioner  and  general  reader,  we  can  heartily  recom- 
mend it  as  an  excellent  resume  of  the  present  state  of 
physiological  science.  As  a  text-book  for  the  student, 
we  think  it  has  no  superior  in  our  language,  and  for 


this  object  we  presume  it  was  chiefly  if  not  expressly 
written.— J/ed.  Examiner. 

The  present  edition  the  author  has  made  a  perfect 
mirror  of  the  science  as  it  is  at  the  present  hour.  As 
a  work  upon  physiology  proper,  the  science  of  the 
functions  performed  by  the  body,  the  student  will  find 
it  all  he  wishes.— iVasAw'He  Journ.  of  Med. 

We  believe  that  it  can  truly  be  said,  no  more  com- 
plete repertory  of  facts  upon  the  subject  treated,  can 
anywhere  be  found.  The  author  has.  moreover,  that 
enviable  tact  at  description  and  that  facility  and  ease 
of  expression  which  render  him  peculiarly  acceptable 
to  the  casual,  or  the  studious  reader.  This  faculty,  so 
requisite  in  setting  forth  many  graver  and  less  attract- 
ive subjects,  lends  additional  charms  to  one  always 
fascinating.— £os<on  Med.  and  Surg.  Journal, 


14 


BLANCHARU    AND    LEA'S 


NEW  PHYSIOLOGICAL  TEXT-BOOK— (Now  Ready). 


HUMAN    PHYSIOLOGY. 


DESIGNED  FOR  THE  USE  OF 

STUDENTS  AND  PRACTITIONERS  OF  MEDICINE. 
By  J.  C.  DALTON,  Jr.,  M.D., 

Professor  of  Physiology  in  the  College  of  Physicians  and  Surgeons,  New  York. 
WITH   TWO   HUNDRED   AND    FIFTY-FOUR   ORIGINAL  ILLUSTRATIONS. 

hi  one  exquisitely  printed  octavo  volume;  extra  cloth,  $4;  leather,  raised  bands,  $4  25. 

The  work  before  us,  however,  in  our  humble  judgment,  is 
precisely  what  it  purports  to  be,  and  will  answer  admirably 
the  purpose  for  which  it  is  intended.  It  is  par  excellence,  a 
text-book ;  and  the  best  text-book  in  this  department  that  we 
have  ever  seen.  We  have  carefully  read  the  book,  and  speak 
of  its  merits  from  a  more  than  cursory  perusal.  Looking  back 
upon  the  work  we  have  just  finished,  we  must  say  a  word  con- 
cerning the  excellence  of  its  illustrations.  No  department  is 
so  dependent  upon  good  illustrations,  and  those  which  keep 
pace  with  our  knowledge  of  the  subject,  as  that  of  physiology. 
The  wood-cuts  In  the  work  before  us  are  the  best  we  have  ever 
seen,  and,  being  original,  serve  to  Illustrate  precisely  what  is 
desired. — Buffalo  Med.  Journal,  March,  1859. 

A  book  of  genuine  merit  like  this  deserves  hearty  praise  be- 
fore subjecting  it  to  any  minute  criticism.  We  are  not  prepared 
to  find  any  fault  with  its  design  until  we  have  had  more  time 
to  appreciate  its  merits  as  a  manual  for  daily  consultation,  and 
to  weigh  its  statements  and  conclusions  more  deliberately.  Its 
excellences  we  are  sure  of;  its  defects  we  have  yet  to  discover. 
It  is  a  work  highly  honorable  to  its  author;  to  his  talents,  his 
industry,  his  training ;  to  the  institution  with  which  he  is  con- 
nected, and  to  American  science. — Boston  Med.  and  Surgical 
Journal,  Feb.  24,  1859. 

A  new  book  and  a  first-rate  one;  an  original  book,  and  one 
which  cannot  be  too  highly  appreciated,  and  which  we  are 
proud  to  see  emanating  from  our  country's  press.  It  is  by  an 
author  who,  though  young,  is  considerably  famous  for  physio- 
logical research,  and  who  in  this  work  has  erected  for  himself 
an  enduring  monument,  a  token  at  once  of  his  labor  and  his 
success. — Nashville  Medical  Journal,  March,  1859. 

Throughout  the  entire  work,  the  definitions  are  clear  and 
precise,  the  arrangement  admirable,  the  argument  briefly  and 
well  stated,  and  the  style  nervous,  simple,  and  concise.  Sec- 
tion third,  treating  of  Reproduction,  is  a  monograph  of  unap- 
proached  excellence  upon  this  subject,  in  the  English  tongue. 
For  precision,  elegance  and  force  of  style,  exhaustive  method 
and  extent  of  treatment,  fulness  of  illustration  and  weight  of 
personal  research,  we  know  of  no  American  contribution  to 
medical  science  which  surpasses  it,  and  the  day  is  far  distant 
when  its  claims  to  the  respectful  attention  of  even  the  best  in- 
formed scholars  will  not  be  cheerfully  conceded  by  all  acquaint- 
ed with  its  range  and  depth. — Charleston  Med.  Journal,  May, 
1859. 

A  new  elementary  work  on  Human  Physiology  lifting  up  its 
voice  in  the  presence  of  late  and  sturdy  editions  of  Kirke's, 
Carpenter's,  Todd  and  Bowman's,  to  say  nothing  of  Dungli- 
son's  and  Draper's,  should  have  something  superior  in  the 
matter  or  the  manner  of  its  utterance  in  order  to  win  for  itself 
deserved  attention  and  a  name.  That  matter  and  that  manner, 
after  a  candid  perusal,  we  think  distinguish  this  work,  and  we 
are  proud  to  welcome  it  not  merely  for  its  nativity's  sake,  but 
for  its  own  intrinsic  excellence.  Its  language  we  find  to  be 
plain,  direct,  unambitious,  and  falling  with  a  just  conciseness 
on  hypothetical  or  unsettled  questions,  and  yet  with  suflicient 
fulness  on  those  living  topics  already  understood,  or  the  path 
to  whose  solution  is  definitely  marked  out.  It  does  not  speak 
exhaustively  upon  every  subject  that  it  notices,  but  it  does 
speak  suggestively,  experimentally,  and  to  their  main  utilities. 
Into  the  suliject  of  Eeproduction  our  author  plunges  with  a 
kind  of  of  loving  spirit.  Throughout  this  interesting  and  ob- 
scure department  he  is  a  clear  and  admirable  teachei',  some- 
times a  bi'illiant  leader. — Am.  Med.  Monthly,  May,  1859. 

We  give  this  book  of  Dr.  Dalton's  a  most  hearty  welcome; 
may  we  have  many  more  as"  deserving  from  American  pens. 
It  exhibits  great  experimental  investigation  and  arduous  labor, 
sure  evidences  of  devotion  to  science  and  professional  pride. 
The  work  is  thoroughly  up  with  the  progress  of  Physiology, 


Diagram,  of  the  Circulation. 


and  has  an  attraction,  presented  by  no  similar  book, 
of  narration  of  recent  opinions  and  experiments 
accompanied  with  illustrations.    We  will  take  plea- 


sure, not  to  say  pride,  in  recommending  this  work 
as  a  text-book  to  our  next  class. — Savannah  Jour- 
nal of  Medicine,  May,  1S59. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


15 


Now  Complete. 


TH  E 

PHYSIOLOGICAL  ANATOMY  AND  PHYSIOLOGY  OF  MAN. 

BY  EGBERT  BENTLEY  TODD,  M.  D.,  F.  R.  S., 

Professor  of  Physiology  in  King's  College,  London,  &c. 
AND 

WILLIAM  BOWMAN,  F.R.S., 

Demonstrator  of  Anatomy  in  King's  College,  London. 
WITH  TWO  HUNDRED  AND  NINETY-EIGHT  BEAUTIFUL  ILLUSTRATIONS  ON  WOOD. 

Complete  in  one  very  handsome  octavo  volume,  of  over  900  large  pages,  leather,  p)rice  $4  50. 


TransKtrse  Section  of  Human  Spleen. 


The  very  great  delay  which  has  occurred  in  the  completion  of  this  work  has  arisen  from  the 
desire  of  the  authors  to  verify  by  their  own  examination  the  various  questions  and  statements 
presented,  thus  rendering  the  work  one  of  peculiar  value  and  authority.  By  the  wideness  of 
its  scope  and  the  accuracy  of  its  facts  it  thus  occupies  a  position  of  its  own,  and  becomes  neces- 
sary to  all  physiological  students. 

1^°  Gentlemen  who  have  received  portions  of  this  work,  as  published  in  the  "Medical  News 
AND  Library,"  can  now  complete  their  copies,  if  immediate  application  be  made.  It  will  be 
furnished  as  follows,  free  by  mail,  in  paper  covers,  with  cloth  backs. 

Parts  I.,  II.,  III.  (pp.  25  to  552),  $2  50. 

Part  IV.  (pp.  553  to  end,  with  Title,  Preface,  Contents,  &c.),  $2  00. 

Also, 
Part  IV.,  Section  II.  (pp.  725  to  end,  with  Title,  Preface,  Contents,  &c.),  f  1  25. 


In  the  present  part  (third)  some  of  the  most  difficult 
subjects  in  anatomy  and  physiology  are  handled  in 
the  most  masterly  manner.  Its  authors  have  stated, 
that  this  work  was  intended  '•  for  the  use  of  the  stu- 
dent and  practitioner  in  medicine  and  surgery,"  and 
we  can  recommend  it  to  both,  confident  that  it  is  the 
most  perfect  work  of  its  kind.  We  cannot  conclude 
without  strongly  recommending  the  present  work  to  j 
all  classes  of  our  readers,  recognizing  talent  and  depth 
of  research  in  every  page,  and  believing,  as  we  do, 
that  the  diffusion  of  such  knowledge  will  certainly 
tend  to  elevate  the  sciences  of  medicine  and  surgery. 
— Dublin  Quarterly  Journal  of  Medical  Sciences. 

It  is  highly  creditable  to  the  authors  of  this  work, 
that,  to  the  exclusioQ  of  theory  and  speculation,.kjaown 


anatomical  facts,  many  of  which  are  the  fruits  of  their 
own  careful  and  laborious  investigations  in  micro- 
scopic anatomy,  are  made  to  serve  as  the  foundations 
for  most  of  their  physiological  deductions.  The  course 
pursued  throughout  the  work  is  strictly  in  accordance 
with  this  view.  Afull  description  of  the  miuute  struc- 
ture, constitution,  and  development  of  an  organ  or 
tissue,  precedes,  always,  and  is  made  the  basis  of  con- 
clusions with  regard  to  its  functions;  physiological 
views  of  their  own,  and  of  others,  are  fairly  and  can- 
didly given,  but  none  are  recommended  as  worthy  of 
being  received  and  adopted,  excepting  such  as  are 
strictly  in  accordance  with  anatomical  facts. — IlUnnis 
and  Indiana  Medical  and  Surgical  Journal. 


16 


BLANCHARD  AND  LEA'S 


THE  STUDENT'S  MANUAL— New  Edition  (Just  Issued). 


MANUAL   OF   PHYSIOLOGY. 

BY  WILLIAM  SENHOUSE  KIRKES,  M.  D., 

Demonstrator  of  Morbid  Anatomy  at  St.  Bartholomew's  Hospital,  London. 

E  nth  gtrntri'tart,  from  t^t  S^fjirlr  anli  S^tbistli  3Lonit)on  HE&ilion. 
With  numerous  additional  Illustrations, 

MAKING  ABOUT  TWO  HUNDRED  IN  ALL. 

In  one  large  and  havclnome  royal  Ylmo.  volume  of  nearly  six  hnndred  pages,  leather,  $2. 


Ciliary  Epiihelizon  of  the  Trachea 


Blood  Crystals  of  the  Guinea-Pig 


In  again  passing  this  work  through  his  hands,  the  author  has  endeavored  to  render  it  a  correct 
exposition  of  the  present  condition  of  the  science,  making  snchaherations  and  additions  as  have 
been  dictated  by  further  experience,  or  as  the  progress  of  investigation  has  rendered  desirable. 
In  every  point  of  mechanical  execution  the  publishers  have  sought  to  make  it  superior  to  former 
editions,  and  at  the  very  low  price  at  which  it  is  offered,  it  will  be  found  one  of  the  handsomest 
and  cheapest  volumes  before  the  profession. 

In  making  these  improvements,  care  has  been  exercised  not  to  increase  its  size,  thus  main- 
taining its  distinctive  characteristic  of  presenting  within  a  moderate  compass  a  clear  and  con- 
nected view  of  its  subjects,  sufficient  for  the  wants  of  the  student. 

A  few  notices  of  tlie  former  editions  are  appended. 


In  the  present  edition,  the  Manual  of  Physiology- 
has  been  brought  up  to  the  actual  condition  of  the 
science,  and  fully  sustains  the  reputation  which  it  has 
already  so  deservedly  attained.  We  consider  the 
work  of  MM.  Kirkes  and  Paget  to  constitute  one  of 
the  very  best  handbooks  of  Physiology  we  possess — 
presenting  just  such  an  outline  of  the  science,  com- 
prising an  account  of  its  leading  facts  and  generally 
admitted  principles,  as  the  student  requires  during 
his  attendance  upon  a  course  of  lectures,  or  for  refer- 
ence whilst  preparing  for  examination. — Am.  Medical 
Journal. 

We  need  only  say,  that,  without  entering  into  dis- 
cussions of  unsettled  questions,  it  contains  all  the 
recent  improvements  in  this  department  of  medical 
science.    For  the  student  beginning  this  study,  and 


the  practitioner  who  has  but  leisure  to  refresh  his 
memory,  this  book  is  invaluable,  as  it  contains  all 
that  it  is  important  to  know,  without  special  details, 
which  are  read  with  interest  only  by  those  who 
would  make  a  specialty,  or  desire  to  possess  a  critical 
knowledge  of  the  subject. — Charleston  MedicalJournal. 

One  of  the  best  treatises  that  can  be  put  into  the 
hands  of  the  student. — London  Medical  Gazette. 

Particularly  adapted  to  those  who  desire  to  possess 
a  concise  digest  of  the  facts  of  Human  Physiology. — 
Biiiisk  and  Foreign  Med.-Cldrurg.  Review. 

We  conscientiously  recommend  it  as  an  admirable 
"  Handbook  of  Physiology." — London  Journal  of  Medi- 
cine. 


AN  ESSAY  TOWARDS  A  CORRECT  THEORY  OF  THE  NERVOUS  SYSTEM.    By 
John  Harrison,  M.  D.    In  one  octavo  volume,  292  pages.   $1  50. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


17 


New  and  Revised  Edition— (Just  Issued.) 


In  one  largo  and 

very  beautiful  octavo  volume 

of  nine  hundred  large 

and  closely  printed  pages, 

with  nearly 

three  hundred  illustrations 

on  stone  and  wood, 

strongly  bound  in  leather,  with 

raised  bands, 

price  $4  25. 


Section  of  Placenta. 


PRINCIPLES  OF  HUMAN  PHYSIOLOGY, 

"WITH  THEIE  CHIEF  APPLICATIONS  TO 

PSYCHOLOGY,  PATHOLOGY,  THERAPEUTICS,  HYGIENE,  AND  FORENSIC  MEDICINE. 
BY  WILLIAM  B.  CARPENTER,  M.D.,  F.R.S., 

Examiner  in  Physiology  and  Comparative  Anatomy  in  the  University  of  London,  &c. 
A  NEW  AMERICAN  FROM  THE  LAST  LONDON  EDITION. 

Edited,  with  Additions,  by  FRANCIS  GURNEY  SMITH,  M.  D., 

Professor  of  the  Institutes  of  Medicine  in  the  Pennsylvania  Medical  College,  &c. 

In  the  preparation  of  this  new 
edition,  the  author  has  spared  no 
labor  to  render  it,  as  heretofore, 
a  complete  and  lucid  exposition 
of  the  most  advanced  condition 
of  its  important  subject.  The 
amount  of  the  additions  required 
to  effect  this  object  thoroughly, 
joined  to  the  former  large  size  of 
the  volume,  presenting  objections 
arising  from  the  unwieldy  bulk 
of  the  work,  he  has  omitted  all 
those  portions  not  bearing  direct- 
ly upon  Human  Physiology,  de- 
signing to  incorporate  ihem  in  his 
forthcoming  Treatise  on  Gene- 
ral Physiology  As  a  full  and 
accurate  text-book  on  the  Phy- 
siology of  Man,  the  work  in  its 
present  condition  therefore  pre- 
sents even  greater  claims  upon 
the  student  and  physician  than 
those  which  have  heretofore  won  for  it  the  very  wide  and  distinguished  favor  which  it  has  so 
long  enjoyed.  The  additions  of  Prof.  Smith  wi'll  be  found  to  supply  whatever  may  have  been 
wanting  to  ihe  American  student,  while  the  introduction  of  many  new  illustrations,  and  the  most 
careful  mechanical  execution,  render  the  volume  one  of  the  most  attractive  as  jet  issued. 


Hand  of  Man  compared  with  that  of  Orang 


The  most  complete  exposition  of  physiology  which 
any  language  can  at  present  give. — Brit,  and  For. 
JJed.-Chirurg.  Review. 

The  most  complete  work  on  the  science  in  our  lan- 
guage.— Am.  Med.  Journal. 

2 


The  greatest,  the  most  reliable,  and  the  best  book 
on  the  subject  which  we  know  of  in  the  English  lan- 
guage.— Stethoscope. 

A  complete  cyclopsedia  of  this  branch  of  science. — 
N.  T.  Med.  Tijnes. 


18 


BLANCHARD    AND    LEA'S 


A  new  American,  from  the  last  and  revised  London  Edition. 


lu  one  large 
and  very  handsome 

octavo  volume 
of  seven  hundred  and  fifty- 
two  pages, 
illustrated  with 
three  hundred  and  nine 
beautiful  wood  engravings. 
Price,  in  extra  cloth,  $4  80 ; 


Leather,  with  raised  bands,      \ 


$5  25. 


Circulatory  A'pjiaratus  of  Pinna. 

PRINCIPLES   OF 

COMPARATIVE  PHYSIOLOGY. 

BY  WILLIAM  B.  CARPENTER,  M.D.,  F.R.S., 

Author  of  " Human  Physiology,"  "The  Microscope  and  its  Revelations,"  &c. 

Thoroughly  brought  up  by  the  author  to  the  date  of  publication,  this  work  will  be  found  to 
fully  maintain  its  exalted  reputation  as  a  complete  and  trustworthy  guide  to  all  parts  of  its  in- 
tricate and  interesting  subject.  The  student  may  therefore  rely  on  finding  in  it  a  lucid  exposi- 
tion of  Comparative  Physiology  in  its  most  recent  aspect,  while  every  effort  has  been  made  to 
render  the  mechanical  and  artislical  execution  of  the  volume  worthy  of  its  scientific  character. 


This  hook  should  not  only  be  read  but  thoroughly- 
studied  by  every  member  of  the  profession.  None  are 
too  wise  or  old,  to  be  beneiited  thereby.  But  espe- 
cially to  the  younger  class  would  we  cordially  com- 
mend it  as  best  fitted  of  any  work  in  the  English 
language  to  qualify  them  for  the  reception  and  com- 
prehension of  those  truths  which  are  daily  being  de- 
veloped in  physiology. — Medical  Counsellw. 

Without  pretending  to  it,  it  is  an  Encyclopedia  of 
the  subject,  accurate  and  complete  in  all  respects — a 
truthful  reflection  of  the  advanced  state  at  which  the 
science  has  now  arrived. — Dublin  Quarterly  Journal  of 
Uedical  Science. 

A  truly  magnificent  work — in  itself  a  perfect  phy- 
siological study. — ManJdng's  Abstract. 

This  work  stands  without  its  fellow.    It  is  one  few 


men  in  Europe  could  have  undertaken ;  it  is  one  no 
man,  we  believe,  could  have  brought  to  so  successful 
an  issue  as  Dr.  Carpenter.  It  required  for  its  produc- 
tion a  physiologist  at  once  deeply  read  in  the  labors 
of  others,  capable  of  taking  a  general,  critical,  and 
unprejudiced  view  of  those  labors,  and  of  combining 
the  varied,  heterogeneous  materials  at  his  disposal,  so 
as  to  form  an  harmonious  whole.  We  feel  that  this 
abstract  can  give  the  reader  a  very  imperfect  idea  of 
the  fulness  of  this  work,  and  no  idea  of  its  unity,  of 
the  admirable  manner  in  which  material  has  been 
brought,  from  the  most  various  sources,  to  conduce  to 
its  completeness,  of  the  lucidity  of  the  reasoning  it 
contains,  or  of  the  clearness  of  language  in  which  the 
whole  is  clothed.  Not  the  profession  only,  but  the 
scientific  world  at  large,  must  feel  deeply  indebted  to 
Dr.  Carpenter  for  this  great  work.  It  must,  indeed, 
add  largely  even  to  his  high  reputation. — Med.  Times. 


MEDICAL  AND   SCIENTIFIC   PUBLICATIONS. 


19 


A  MANUAL  FOR  THE  MICROSCOPE— (Lately  Published.) 

THE  MICROSCOPE  AND  ITS  REVELATIONS. 

BY  WILLIAM  B.  CARPENTER,  M.  D.,  F.  R.  S., 

Author  of  "  Human  Physiology,"  "  Comparative  Physiology,"  &e. 
WITH    AN   APPENDIX    CONTAINING 

THE  APPLICATIONS  OF  THE  MICROSCOPE  TO  CLINICAL  MEDICINE, 
BY  F.  GURNEY  SMITH,  M.  D., 

Professor  of  Institutes  of  Medicine  in  the  Pennsylvania  Medical  College,  &a. 

Illustrated  with  Four  Hundred  and  Thirty-four  exquisite  Wood  Engravings. 

In  one  large  and  very  handsome  octavo  volume  of  724  pages'    Price,  iri  extra  cloth,  $4 ;  in 

leather,  f4  50. 


liiJ  -^ 


Smith  and  Beck''s  Student''s  Microscope. 


Fungoid  Vegetation  in  Stomach  of  Passidiis. 

To  the  student  of  physiological  and  micro- 
scopic science,  this  work  may  be  regarded  as 
an  indispensable  handbook.  Commencing  with 
a  history  of  the  instrument,  it  proceeds  with  an 
elaborate  description  of  all  the  more  useful  and 
improved  forms  of  the  microscope  as  at  present 
employed,  and  their  comparative  values  for  dif- 
ferent'purposes,  together  with  their  accessories 
and  the  various  implements  facilitating  their 
use.  This  is  followed  by  minute  directions  for 
the  prosecution  of  microscopic  research,  em- 
bracing not  only  the  use  of  the  instrument,  but 
all  the  necessary  manipulations  for  the  prepara- 
tion of  objects  of  various  kinds.     After  thus 


showing  how  to  use  the  microscope,  the  author  proceeds  to  indicate  what  has  been  done  by  its 
assistance,  losing  no  opportunity  of  pointing  out  what  remains  for  investigation,  and  of  indicating 
the  directions  in'which  further  explorations  will  be  most  likely  to  lead  to  important  results.  In 
carrying  out  this  plan  a  series  of  chapters  is  given,  commencing  with  the  minute  vegetable 
forms  and  protophyta,  and  terminating  with  the  vertebrata,  thus  embodying  a  general  view  of 
the  microscopic  structure  of  all  organized  beings.  Chapters  are  also  devoted  to  the  mineral 
kingdom,  and  to  the  applications  of  the  microscope  to  geology.  In  the  Appendix,  Dr.  Smith 
has  presented  a  condensed  but  thorough  sketch  of  the  uses  of  the  microscope  in  the  prosecution 
of  clinical  diagnosis,  with  an  account  of  the  principal  microscopes  manufactured  in  this  country. 
The  volume  throughout  is  profusely  illustrated  :  and  is  printed  in  the  handsomest  manner, 
forming  one  of  the  most  creditable  specimens  of  art  as  yet  issued  in  this  country. 

The  preeminent  reputation  of  Dr.  Carpenter  as  a  physiologist,  a  microscopist,  and  a  teacher, 
points  him  out  as  especially  fitted  to  produce  a  M'ork  serving  as  an  introduction  for  the  beginner, 
and  as  a  reference  book  for  the  advanced  student. 


Although  originally  not  intended  as  a  strictly  I  a  complete  and  satisfactory  collection  of  microscopic 
medical  work,  the  additions  hy  Prof.  Smith  give  it  a  facts  bearing  upon  physiology  and  practical  medicine 
positive  claim  upon  the  profession,  for  which  we  douht  |  as  is  contained  in  Prof  Smith's  appendix ;  and  this  of 
not  he  will  receive  their  sincere  thanks.  Indeed,  we  1  itself,  it  seems  to  us,  is  fully  worth  the  cost  of  tbe 
know  not  where  the  student  of  medicine  will  find  such    volume.— XoMwrnZfe  Medical  Review,  Nov.  1856. 


20 


BLANCHARD    AND    LEA'S 


A  LIBRARY  OF  ZOO-CHEMICAL  SCIENCE-(Just  Issued.) 


.y-^o 


Blood  Crystals  of  Human  Venous  Blood. 


Urinary  Deposit  of  Triple  Phosphate,  in  Paralysis. 


PHYSIOLOGICAL  CHEMISTRY. 

BY  PROFESSOR  C.  G.  LEHMANN. 

Translated  from  the  Second  Edition  by  GEORGE  E.  DAY,  M.D.,  F.R.  S.,  &c. 
Edited  by  R.  E.  ROGERS,  M.  D., 

Professor  of  Chemistry  in  the  Medical  Department  of  the  University  of  Pennsylvania,  &c. 

With  Illxtstrations  selected  feom  Funke's  "Atlas  of  Physiological  Chemistry," 

AND  AN  APPENDIX  OF  PLATES. 

Complete  in  two  large  and  handsome  octavo  volumes  of  ahoiit  1200  pages,  with  nearly  200 
Illustrations.     Extra  cloth,  $6. 

This  o-reat  work,  universally  acknowledged  as  the  most  complete  and  authoritative  exposition 
of  the  principles  and  details  of  Zoochemistry,  in  its  passage  through  the  press,  has  received 
from  Professor  Rogers  such  care  as  was  necessary  to  present  it  in  a  correct  and  reliable  form. 
To  such  a  work  additions  were  deemed  superfluous,  but  several  years  having  elapsd  between 
the  appearance  in  Germany  of  the  first  and  last  volume,  the  latter  contained  a  supplement,  em- 
bodving  numerous  corrections  and  additions  resulting  from  the  advance  o^  the  science.  These 
have  all  been  incorporated  in  the  text  in  their  appropriate  places,  while  the  subjects  have  been 
still  further  elucidated  by  the  insertion  of  illustrations  from  the  Atlas  of  Dr.  Otto  Funke.  With 
the  view  of  supplying  the  student  with  the  means  of  convenient  comparison,  a  large  number 
of  wood-cuts,  from  works  on  kindred  subjects,  have  also  been  added  in  the  form  of  an  Appendix 
of  Plates. 

Within  the  last  few  years  the  vast  extension  of  the  positive  facts  of  science  has  demonstrated 
the  connection  and  interdependence  of  the  various  branches  of  knowledge.  The  lines  of  de- 
marcation have  gradually  disappeared,  and  the  student  of  physiology  can  no  longer  confine  him- 
self to  the  scalpel  and  the  microscope.  At  this  time,  therefore,  a  work  like  the  present  becomes 
a  necessity  to  all  earnest  inquirers  mto  the  processes  of  nature,  accumulating  as  it  does,  to  the 
development  of  Physiology,  all  the  aids  afforded  by  the  cognate  departments  of  science  in  their 
most  recent  and  advanced  condition. 


The  most  important  contribution  as  yet  made  to 
Physiological  Chemistry— jtni.JoMrraaZ  Med.  Sciences. 

The  present  volumes  belong  to  the  small  class  of 
medical  literature  which  comprises  elaborate  works 
of  the  highest  order  of  vaeriV.—  Montreal  Med.  Chro- 
nicle. 

Already  well  known  and  appreciated  by  the  scien- 
tific world,  Professor  Lehmann's  great  work  requires 
no  laudatory  sentences,  as,  under  a  new  garb,  it  is  now 
presented  to  us.  The  little  space  at  our  command 
would  ill  suffice  to  set  forth  even  a  small  portion  of 
its  excellences.  To  all  whose  studies  or  professional 
duties  render  the  revelations  of  Physiological  Che- 


mistry at  once  interesting  and  essential,  these  volumes 
will  be  indispensable.  Highly  complimented  by  Euro- 
pean reviewers,  sought  for  with  avidity  by  scholars  of 
every  nation,  and  admirably  written  throughout,  it  is 
sure  to  win  a  welcome  and  to  be  thoroughly  studied. 
— Boston  Med.  and  Surg  Journal. 

The  work  of  Lehmann  stands  unrivalled  as  the  most 
comprehensive  book  of  reference  and  information  ex- 
tant on  every  branch  of  the  subject  on  which  it  treats. 
— Edinburgh  Monthly  Journal  of  Medical  Sciences. 

All  teachers  must  possess  it,  and  every  intelligent 
physician  ought  to  do  hkewise..— Southern  Med.  and 
Surg.  Journal. 


MEDICAL   AND  SCIENTIFIC   PUBLICATIONS. 


21 


HANDBOOK  OF  CHEMICAL  PHYSIOLOGY— (Just  Issued.) 


MANUAL  OF  CHEMICAL   PHYSIOLOGY. 

J^rom  tljc  djicrman  of 
PROFESSOR  C.  a.  LEHMANN,  M.  D. 

TRANSLATED,  WITH  NOTES  AND  ADDITIONS 

BY   J.   CHESTON    MORRIS,   M.D. 

WITH    AN 

INTRODUCTORY  ESSAY  ON  VITAL  FORCE, 

BY  SAMUEL  JACKSON,  M.  D., 

Professor  of  Institutes  of  Jledicine  in  the  University  of 
Pennsylvania. 

WITH  HANDSOME  ILLUSTRATIONS  ON  WOOD. 

Ill  one  very  neat  octavo  volume,  of  tlivee  hundred  and  thirty- 
four  pages,  extra  cloth,  $2  25. 

Section  of  Skin  treated  intth  Acetic  Acid. 

From  Professor  Jackson's  Introductory  Essay. 

In  adopting  the  handbook  of  Dr.  Lehmann  as  a  manual  of  Organic  Chemistry  for  the  use  of 
the  students  of  the  University,  and  in  recommending-  his  original  work  of  PhysIological  Che- 
mistry for  their  more  mature  studies,  tJie  high  value  of  his  researches,  and  the  great  weight  of 
his  authority  in  that  important  department  of  medical  science  are  fully  recognized. 


We  have  read  this  volume  with  great  interest  and 
much  profit,  intendins:  to  make  an  epitome  of  its  con- 
tents for  the  benefit  of  our  readers,  but  finding  that  it 
is  itself  but  an  abridgment,  which  cannot  easily  be 
further  condensed,  we  are  compelled  to  relinquish 
that  design,  and  terminate  this  notice  by  expressing 
the  wish  that  every  student  and  practitioner  in  the 
Peninsular  State  could  be  the  owner  of  a  copy  of  Leh- 
mann's  Chemical  Physiology. — Peninsular  Med.  Jour- 
nal, June,  1856. 

In  its  more  concise  and  simplified  form  this  hand- 
book of  Physiological  Chemistry  gives  the  student  an 


opportunily  of  examining  the  vast  and  laborious  re- 
searches of  the  German  physiologists  in  the  field  of 
Zoo-Chemistry.  AVe  can  but  admire  the  patient  labor 
exhibited  on  every  page.  With  what  careful  analysis 
has  every  one  of  the  organic  compounds  been  tested 
by  the  chemical  forces — how  carefully  and  yet  accu- 
rately have  all  the  chemical  laws  been  brought  to  bear 
upon  the  living  tissues  of  the  human  body.  We  are 
well  satisfied  to  leave  the  readers  of  this  work  (and 
every  one  who  is  desirous  to  be  familiar  with  modern 
physiology  should  read  it),  to  determine  each  one  for 
himself  the  important  doctrine  here  taught  — Va.  Med. 
Journal,  May,  1856. 


New  and  Improved  Edition— (Just  Issued.) 


A  PRACTICAL  HANDBOOK  OF  MEDICAL  CHEMISTRY  i 

BY  JOHN  E.  BOWMAN,  F.  C.  S., 

Professor  of  Practical  Chemistry  in  King's  College,  London. 

.Sitonir  Emtritan,  from  t^j  QIf)tr&  anlr  3£t£bist&  HLonlJoit  35IJition. 


WITH  NUMEROUS  ILLUSTRATIONS. 

Iti  07ie  neat  royal  Viino.  volume  of  nearly  300  pages  ;  extra  cloth, 
price  $1  25. 

Presenting,  in  a  condensed  and  convenient  form,  at  a  very  low  price, 
the  applications  of  Chemistry  to  the  practical  purposes  of  Clinical  Me- 
dicine, this  work  supplies  a  want  which  lias  long  been  felt  by  the  phy- 
sician. The  numerous  editions  which  have  been  called  for  both  in 
England  and  this  country,  sufficiently  attest  the  success  with  which  the 
author  has  carried  out  his  plan. 

Analysis  of  Diabetic  Urine. 


22 


BLANCHARD    AND    LEA'S 


GRAHAM'S   CHEMISTRY— Now  Complete  (1858.) 


ELEMENTS  OF  INORGANIC  CHEMISTRY; 

INCLUDING 

THE  APPLICATIONS  OF  THE  SCIENCE  IN  THE  ARTS. 
BY  THOMAS  GRAHAM,  R  R.  S.  L.  and  E., 

Late  Professor  of  Chemistry  in  University  College,  London,  &c. 

Edited  by  HENRY  WATTS,  B.  A.,  and  ROBERT  BRIDGES,  M.D. 

SECOND  AMERICAN  FROM  THE  SECOND  REVISED  AND  ENLARGED  LONDON  EDITION. 

Complete  in  One  Volume,  with  233  Illustrations  on  Wood. 

In  one  very  large  and  handsome  octavo  volume  o/850  very  large  pages.  Price,  in  extra  cloth, 
$4;  leather,  raised  lands,  $4  50. 

*ifc*  Part  II.  (completing  the  work),  from  p.  431  to  end,  with  Index,  Title  matter,  &e.,  may  be 
liad  separate,  in  stout  wrappers,  uncut,  for  binding,  price  $2  50,  on  receipt  of  which  it  will 
be  forwarded  by  mail,  free  of  postage,  to  any  address.  Gentlemen  desirous  of  completing 
their  copies  are  requested  to  apply  for  it  without  delay. 

The  long  delay  which  has  intervened  since  the 
appearance  of  the  first  portion  of  this  work,  has 
rendered  necessary  an  Append  ix,  embodying  t  he 
numerous  and  important  investigations  and  dis- 
coveries of  the  last  few  years  in  the  subjects 
contained  in  Part  I.  This  occupies  a  large  por- 
tion of  Part  11.,  and  will  be  found  to  present  a 
complete  abstract  of  the  most  recent  researches 
in  the  general  principles  of  the  science,  as  well 
as  all  details  necessary  to  bring  the  whole  work 
thoroughly  up  to  the  present  time  in  all  depart- 
ments of  Inorganic  Chemistry. 

It  is  a  very  acceptable  addition  to  tlie  library  of  stand- 
ard books  of  every  chemical  student.  Mr.  Watts,  well 
known  as  the  translator  of  the  Cavendish  Society  edi- 
tion of  Gmelin's  Chemistry,  has  made  in  the  supple- 
ment an  able  reszwne  of  the  progress  of  the  science  since 
the  publication  of  the  first  volume.  It  is  plain,  from 
the  number  and  importance  of  the  topics  there  dis- 
cussed, that  great  progress  has  been  made  in  the  inter- 
val, both  in  chemical  physics  and  in  general  inorganic 
chemistry.  No  reader  of  English  works  on  this  science 
can  afford  to  be  without  this  edition  of  Prof.  Graham's 
Elements. — SillvniarCs  Journal,  March,  1858. 

J?Vo»i  Prof.  0.  P.  Hubbard,  Dartmouth  College,  N.  H., 
May  20,  1S58. 
I  am  impressed  with  the  great  amount  and  variety 
of  its  contents,  and  its  great  value  to  chemists  who 
have  not  access  to  all  the  current  literature  of  the  day 
in  chemistry.  Its  appendix  embraces  a  great  deal  of 
recent  investigation  not  found  in  any  other  American 
republication. 

From  Professor  J.  L.  Crawcour,  New  Orleans  School  of 
Medicine,  May  9, 1858. 
It  is,  beyond  all  question,  the  best  systematic  work 
on  Chemistry  in  the  English  language,  and  I  am  grati- 
fied to  find  that  an  American  edition  at  a  moderate 
price  has  been  issued,  so  as  to  place  it  within  the  means 
of  students.  It  will  be  the  only  text-book  I  shall  now 
recommend  to  my  class. 

From  Prof.  E.  N.  Horsford,  Harvard  College,  April  27, 
1858. 
It  has,  in  its  earlier  and  less  perfect  editions,  been 
familiar  to  me,  and  the  excellence  of  its  plan  and  the 
clearness  and  completeness  of  its  discussions,  have 
long  been  my  admiration. 


Osmometer. 

From  Prof.  Wolcoit  Gihhs,  New  York  Free  Academy, 

May  25, 1858. 

The  work  is  an  admirable  one  in  all  respects,  and 

its  republication  here  cannot  fail  to  exert  a  positive 

influence  upon  the  progress  of  science  in  this  country. 


HANDBOOK  OF  CHEMISTRY; 

THEORETICAL,  PRACTICAL,  AND   TECHNICAL. 
BY  F.  A.  ABEL  and  C.  L.  BLGXAM. 

WITH  A  PREFACE  BY  A.  W.  HOFMANN,  M.  D., 

gLnlJ  Numxrou5  Illustrations  on  Mooli. 

In  07ie  large  and  liandsome  octavo  volume  of  nearly  100  pages  ;  extra  cloth,  price  $3  25. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


23 


NEW  AND  ENLARGED  EDITION— Now  Ready  (July  1859). 
THE   STUDENT'S   MATTIJAL   OP  CHEMISTRY. 


In  one  large  royal  12mo.  volume 

of  600  pages, 

with  197  illustrations  on  wood. 

In  leather,  $1  65 ; 

extra  cloth,  $1  50. 


Induction  Coil. 

ELEMENTARY   CHEMISTRY; 

THEORETICAL    AND    PRACTICAL. 
BY  GEORGE  FOWNES,  F.R.S., 

Late  Professor  of  Practical  Chemistry  in  University  College,  London. 

Edited  by  ROBERT  BRIDGES,  M.D., 

Professor  of  Chemistry  in  the  Philadelphia  College  of  Pharmacy, 


jFrom  li)t  Stbtntf)  ffni 


^thistii 


.oniDn  B&ition:.      ,^='^r:~^.  —ds^- 


Gas  Furnace  for  Organic  Analysis. 

The  seventh  edition  of  thi»  popular  manual,  published  a  few  months  since  in  London  under 
the  editorial  supervision  of  Messrs.  Benee  Jones  and  A.  W.  Hoffman,  received  a  thorough  re- 
vision which  has  brought  it  fully  up  to  the  present  state  of  the  science.  The  department  of  Or- 
ganic Chemistry  is  of  course  the  one  in  which  the  greatest  amount  of  addition  was  requisite, 
and  in  introducing  what  was  necessary  to  render  it  a  fair  exposition  of  the  subject  in  its  most 
advanced  condition,  care  has  been  exercised  to  retain  the  characters  ol  clearness  and  condensa- 
tion which  have  rendered  the  work  so  deservedly  a  favorite  with  all  classes  of  students,  while 
the  completeness  with  which  all  branches  of  the  subject — Chemical  Physics  as  well  as  Inor- 
ganic and  Organic  Chemistry — are  presented  is  in  no  way  interfered  with  To  accommodate 
the  additions,  the  size  of  the  page  has  been  enlarged,  notwithstanding  which  the  number  has 
been  increased  by  nearly  fifcy  pages.  The  present  enlarged  and  improved  edition,  presenting 
the  matter  of  an  ordinary  large  octavo  volume  in  so  small  a  compass  and  at  so  very  Iowa  price, 
will  therefore,  it  is  hoped,  maintain  the  popularity  which  the  work  has  always  enjoyed  with 
both  teachers  and  students.    A  few  notices  of  previous  editions  are  subjoined. 


We  know  of  no  better  text-book,  especially  in  the 
difficult  department  of  organic  chemistry,  upon  which 
it  is  particularly  full  and  satisfactory.  We  would  re- 
commend it  to  preceptors  as  a  capital  '-office  book"  for 
their  students  who  are  beginners  in  Chemistry.  It  is 
copiously  illustrated  with  excellent  wood-cuts,  and 
altogether  admirably  "got  up." — N.  J.  Med.  Reporter. 

A  standard  manual,  which  has  long  enjoyed  the 
reputation  of  embodying  much  knowledge  in  a  small 
space.  The  author  has  achieved  the  difficult  task  of 
condensation  Avith  masterly  tact.  His  book  is  concise 
without  being  dry,  and  brief  without  being  too  dog- 
matical or  general. — Virginia  Med.  and  Surg.  Journal. 


We  unhesitatingly  recommend  it  to  medical  stu- 
dents.— M.  W.  Med.  and  Surg.  Journal. 

One  of  the  best  elementary  works  on  Chemistry  ac- 
cessible to  the  American  and  English  student. — iV.  Y. 
Jownal  of  Medicine. 

The  work  of  Dr.  Fownes  has  long  been  before  the 
public,  and  its  merits  have  been  fully  appreciated  as 
the  best  text-book  on  Chemistry  now  in  existence. 
We  do  not,  of  course,  place  it  in  a  rank  superior  to 
the  works  of  Brande,  Graham,  Turner,  Gregory,  or 
Gmelin,  but  we  say  that,  as  a  work  for  students,  it  is 
preferable  to  any  of  them. — London  Journ.  of  Medicine. 


24 


BLANCHARU    AND    LEA'S 


APPLIED    CHEMISTRY. 


In  two 

very  handsome 

octavo  volumes,  extra  cloth, 

containing 

about  one  thousand  pages, 

and  nearly 

five  hundred  splendid 

wood  engravings. 

Price  $6, 


Apparatus  for  Rosin  Gas. 

TECHNOLOGY: 

OR,  CHEMISTRY  APPLIED  TO  THE  ARTS  AND  TO  MANUFACTURES. 

BY  PROFESSOR  F.  KNAPP. 

EDITED,    WITH    NUMEROUS    NOTES    AND    ADDITIONS, 

BY  DR.  EDMUND  RONALDS  and  DR.  THOMAS  RICHARDSON. 

With  American  Additions  by  Pkof.  WALTER  R.  JOHNSON. 

The  innumerable  applications  of  chemical  science  to  all  branches  of  art  and  manufacture, 
ender  a  work  like  the  present  indispensable  to  all  practical  men.  The  very  full  and  accurate 
escriptions  of  the  most  approved  processes,  elucidated  by  the  very  full  series  of  beautiful  illus- 
rations,  give  it  a  value  w^hich  can  hardly  fail  to  be  appreciated  in  an  age  and  country  such  as  this. 


MEDICAL  CHEMISTRY; 

FOR  THE  USE  OF  STUDENTS  AND  THE  PROFESSION. 

Being  a  Manual  of  the  Science,  with  its  applications  to  Toxicology, 
Physiology,  Therapeutics,  Hygiene,  &c. 

BY  D.  P.  GARDNER,  M.D., 

l7i  o?ie  royal  12mo.  volume,  extra  cloth,  vdth  ilhistrations .    Price  $1. 

This  volume  possesses  especial  claim  on  the  attention  of  the  profes 
sion  as  being  the  only  work  in  which  the  subject  is  systematically  treated 
with  a  view  to  its  bearings  on  medicine.  The  sole  aim  of  the  author 
throughout  has  been  to  render  it  the  Chemistry  for  the  Medical  Student. 


Marsh's  Test  for  Arsenic. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


25 


M  INTRODUCTION^  TO  PRACTICAL  CHEMISTRY, 

INCLUDING  ANALYSIS. 
BY  JOHN  E.  BOWMAN, 

Professor  of  I'ractical  Chemistry  in  King's  College, 
London,  &.c. 

■With  One  Hundred  Illustrations. 

Se.ond  American,  from  the  Second  and  Revised 

London  Edition, 

I?i  one  neat  royal  Ylmo.  volume,  extra  cloth,  of  300 
pages,  price  $1  25.    (Just  Issued.) 

This  little  work,  giving  in  a  clear,  concise,  and 
elementary  form  such  instruction  as  is  required  by 
the  student  of  practical  chemistry,  has  deservedly 
become  a  favorite  vv'ith  those  for  whom  it  is  designed. 
The  author  has  throughout  endeavored  lo  present  the 
simplest  modes  and  apparatus  leading  to  correct  re- 
sults. 
Decantalion  and  Filtration. 


MOHR  AND   REDWOOD'S  PRACTICAL  PHARMACY. 

practicalIpharmacy. 

THE  AEEANGEMENTS,  APPAEATTIS,  AND  MANIPULATIONS  OF  THE  PHAEMACETI- 
TICAL  SHOP  AND  LABORATORY. 

BY  FRANCIS  MOHR,  Ph.  R, 

Assessor  PharmacifE  of  the  Koyal  Prussian  College  of  Medicine ; 

AND  THEOPHILUS  REDWOOD, 

Professor  of  Chemistry  and  Pharmacy  to  the  Pharmaceutical  Society  of  Great  Britain. 

Edited,  ttith  extensive  Additions,  by  "WILLIAM  PROCTER,  Jr., 

Professor  of  Pharmacy  in  the  Philadelphia  College  of  Pharmacy. 

ILLUSTRATED    WITH   FIVE    HUNDRED    ENGRAVINGS    ON   WOOD. 

In  one  large  and  very  handsome  octavo  volume,  of  nearly  600  images,  extra  c?o<7i,^jriVe  $2  75. 

J". 

This  work  will  be  found  of  great  va- 
lue, not  only  to  apothecaries,  but  also  to 
physicians  who  live  at  a  distance  from 
competent  pharmaceutists.  Compre- 
hending, as  it  does,  all  the  manipula- 
tions and  operations  of  preparing  and 
dispensing  medicines,  from  the  extrac- 
tion of  a  stopper  or  the  tying  of  a  cork, 
to  the  most  complicated  and  delicate 
processes  of  pharmacy,  illustrated  at 
every  step  with  a  profusion  of  engrav- 
ings, it  may  be  regarded  as  an  indispen- 
sable assistant  to  the  druggist  and  coun- 
try practitioner,  while  its  very  moderate 
price  places  it  within  the  reach  of  all. 

Water-bath  Funnel. 


It  is  a  book,  however,  which  will  be  in  the  hands  of 
almost  every  one  who  is  much  interested  in  pharma- 
ceutical operations,  as  we  know  of  no  other  publicar 
tion  so  well  calculated  to  fill  a  void  long  felt. — Medical  j 
Examiner. 

This  work  is  very  full  and  complete,  and  details,  in  i 
a  style  uncommonly  clear  and  lucid,  not  only  the  ' 


more  complicated  and  difficult  processes,  but  those  not 
less  important  ones,  the  most  simple  and  common. — 

Buffalo  Medical  Journal. 

The  country  practitioner  who  is  obliged  to  dispense 
his  own  medicines,  will  find  it  a  most  valuable  assist- 
ant.— Monthly  Journal  and  Metrospect. 


26 


BLANCHARD    AND    LEA'S 


A  DISPENSATORY  AND  PHARMACY  COMBINED.' 


In  one 

very  handsome 

octavo  volume, 

extra  cloth, 

of 
550  pnges. 


With  nearly 

two  hundred  and  fifty 

illustrations. 

Price  S2  75. 


Wiegand^s  Powder  Folder. 


M  INTPiODUCTION  TO  PRACTICAL  PHARMACY. 

DESIGNED  AS 

A  TEXT-BOOK  FOR  THE  STUDENT  AND  AS  A  GUIDE  FOR  THE  PHY- 
SICIAN AND  PHARMACEUTIST. 
WITH     MANY    FORMUL/E    AND    PRESCRIPTIONS. 
BY  EDWARD  PARRISH, 

Principal  of  ihe  School  of  Practical  Pharmacy,  Philadelphia. 

This  work,  while  necessary  to  the  edu- 
cated pharmaceutist,  will  also  be  ibund  of 
the  greatest  importance  to  those  practi- 
tioners who,  residing  at  a  distance  from 
apothecaries,  are  called  upon  to  dispense 
as  well  as  to  prescribe.  The  author  has 
not  only  given  a  thorough  outline  of  the 
principles  ofpharinacy  and  its  general  pro- 
cesses, but  has  also  presented  their  special 
applications  in  the  details  of  preparing  all 
the  difierent  classes  of  medicines,  illustrat- 
ed with  numerous  engravings  of  apparatus 
and  implements,  which,  in  all  cases,  are 
of  the  simplest  description.  Under  the 
different  heads  are  contained  many  tables 
and  syllabi  of  classes  of  medicines,  pre- 
senting the  remedies  of  the  United  States 
Pharmacopoeia,  together  with  many  new  ones,  so  arranged  as  to  render  their  relations  of  easy 
comprehension,  and  embodying  all  the  more  important  formulae  of  the  Pharmacopoeia,  as  well 
as  many  others  from  the  practice  of  distinguished  physicians,  not  hitherto  in  print.  Especial 
notice  has  been  taken  of  the  numerous  important  remedies  recently  obtained  from  our  indige- 
nous flora,  and  their  composition  and  preparation  pointed  out. 

The  long  experience  of  the  author  as  a  teacher  of  pharmacy  has  rendered  him  familiar  with 
the  wants  of  students,  and  entirely  competent  to  supply  them.  He  has  accordingly  descended 
to  those  minutiae  which  so  often  interpose  difficulties  in  the  way  of  the  young  practitioner,  who 
has  hitherto  had  no  practical  guide  to  point  out  the  modes  of  overcoming  them. 


Board,  Rolltr,  and  Punch/or  Lozenges 


This  is  a  well-timed  and  most  valuable  work.  It  is 
designedly  adapted  to  meet  the  wants  both  of  the 
practical  pharmaceutist,  and  of  the  physician ;  and 
to  both  these  classes  we  doubt  not  it  will  prove  an 
acceptable  offering  There  are  thousands  of  prac- 
titioners throughout  the  country  who  are  neces- 
sarily compelled  to  compound  their  own  medicines, 
who,  however  well  they  may  be  informed  on  the 
subject  of  therapeutics,  it  must  be  acknowledged  are 
but  illy  instructed  in  the  art  of  preparing  reme- 
dies for  use.  In  the  work  now  offered  to  the  public, 
Mr.  Parrish  has  undertaken  to  supply  the  want  of  ele- 
mentary knowledge  on  this  subject  by  prepariug  a 
book  containing  the  leading  facts  and  principles  of 
pharmacy,  presented  in  so  simple  and  clear  a  man- 
ner, and  go  well  illustrated  by  engravings,  as  to  be 
perfectly  intelligible  to  all.  We  take  great  pleasure 
in  recommending  this  work  to  our  readers,  and  espe- 
cially to  country  practitioners,  as  we  are  satisfied  that 
they  will  find  it  of  essential  aid,  in  enabling  them  to 
discharge  aright  that  difficult  part  of  their  daily  task, 
to  wit:  preparing  and  compounding  their  remedies. — 
St.  Louis  Med.  and  Surg.  Journal. 

It  is  with  reluctance  and  much  regret  that  we  are 
compelled  to  give  the  above  work  only  a  hook  notice. 
It  was  our  wish  and  intention  to  attempt  an  extended 
analysis  of  its  contents  that  our  readers  might  judge 


somewhat  for  themselves  of  its  great  and  numerous 
merits,  but  the  subject  matter  is  of  such  a  nature  as 
to  forbid  anything  like  a  review.  All  that  we  can  say 
of  it  is  that  to  the  practising  physician  and  especially 
the  country  physician  who  is  generally  his  own  apo- 
thecary, there  is  hardly  any  book  that  might  not  better 
be  dispensed  with.  It  is  at  the  same  time  a  dispensa- 
tory and  a  pharmacy. — Louisville  Review. 

A  careful  examination  of  this  work  enables  us  to 
speak  of  it  in  the  highest  terms,  as  being  the  best 
treatise  on  practical  pharmacy  with  which  we  are  ac- 
quainted, and  an  invaluable  vade-mecum,  not  only  to 
the  apothecary  and  to  those  practitioners  who  are 
accustomed  to  prepare  their  own  medicines,  but  to 
every  medical  man  and  medical  student. — Boston 
Med.  and  Surg.  Journal. 

This  is  altogether  one  of  the  most  useful  books  we 
have  seen.  It  is  just  what  we  have  long  felt  to  be 
needed  by  apothecaries,  students,  and  practitioners  of 
medicine,  most  of  whom  in  this  country  have  to  put 
up  their  own  prescriptions.  It  bears,  upon  every  page, 
the  impress  of  practical  knowledge,  conveyed  in  a 
plain  common  sense  manner,  and  adapted  to  the  com- 
prehension of  all  who  may  read  it.  No  detail  has  been 
omitted,  however  trivial  it  may  seem,  although  really 
important  to  the  dispenser  of  va^HitAne.— Southern  Med. 
and  Surg.  Journal, 


MEDICAL  AND  SCENTIFIC   PUBLICATIONS. 


27 


Enlarged  and  Improved  Edition. 


A  UNIVERSAL  FORMULARY 


CONTAINING  THE 

METHODS    OF    PREPARING   AND    ADMINISTERING 

OFFICINAL  AND  OTHER  MEDICINES. 

The  whole  adapted  to  Physicians  and  Pharmaceutists. 

BY  R.  EGLESFELD  GRIFFITH,  M.  D. 

A  Ne-vv  Edition,  carefully  Revised  and  much  Kxtended, 

BY  ROBERT  P.  THOMAS,  M.  D., 


Professor  of  Materia  Medica  in  the  Philadelphia  College  of  Pharmacy,  &c. 


In  one 

handsome  octavo 

volume,  with 

Illustrations. 


Containing  six 

hundred  and  fifty 

large  pages, 

mostly  double 

columns. 

Price,  in  leather, 

extra  chith,  $3. 


Coating  Pills  with  Gelatine. 


Besides  the  Formulary  proper,  this  work  contains  a  vast  amount  of  information  indispensa- 
ble for  daily  reference  by  the  practising  physician  and  apothecary,  embracing  Tables  of  Weights 
and  JMeasures,  Specific  Gravity,  Temperature  for  Pharmaceuiical  Operations,  Hydrometrical 
Equivalenis,  Specific  Gravities  of  some  of  the  Preparations  of  the  Pharmacopoeias,  Relation 
between  different  Thermometrical  Scales,  Explanation  of  Abbreviations  used  in  Formulae, 
Vocabulary  of  Words  used  in  Prescriptions,  Observations  on  the  Management  of  the  Sick 
Room,  Doses  of  Medicines,  Rules  for  the  Administration  of  Medicines,  Management  of  Con- 
valescence and  Relapses,  Dietetic  Preparations,  not  included  in  the  Formulary,  List  of  Incom- 
patibles,  Posological  Table,  Table  of  Pharmaceutical  Names  which  differ  in  the  Pharmacopoeias, 
Officinal  Preparations  and  Directions,  and  Poisons. 

Three  complete  and  extended  Indexes  render  the  work  especially  adapted  for  immediate  con- 
sultation. One  of  Diseases  and  their  Remedies,  presents  under  the  head  of  each  disease  the 
remedial  agents  which  have  been  usefully  exhibited  in  it,  with  reference  to  the  formulas  con- 
taining them — while  another  of  Pharmaceutical  and  Botanical  Names,  and  a  very  thorough 
General  Index  afford  the  means  of  obtaining  at  once  any  information  desired.  The  Formulary 
itself  is  arranged  alphabetically,  under  the  heads  of  the  leading  constituents  of  the  prescriptions. 


It  was  a  work  requiring  much  perseverance,  and 
when  published  was  looked  upon  as  by  far  the  best 
work  of  its  kind  that  had  issued  from  the  American 
press.  Prof.  Thomas  has  certainly  "improved,"  as 
well  as  added  to  this  Formulary,  and  has  rendered  it 
additionally  deserving  of  the  confidence  of  pharma- 
ceutists and  physicians. — Am.  Journal  of  Pharmacy. 

We  are  happy  to  announce  a  new  and  improved 
edition  of  this,  one  of  the  most  valuable  and  useful 
works  that  have  emanated  from  an  American  pen.  It 
would  do  credit  to  any  country,  and  will  be  found  of 
daily  usefulness  to  practitioners  of  medicine;  it  is 
better  adapted  to  their  purposes  than  the  dispensa- 
tories.— Southern  Med.  aiid  Surg.  Journal, 

A  new  edition  of  this  well-known  work,  edited  by 
R.  P.  Thomas,  M.  D.,  affords  occasion  for  renewing  our 
commendation  of  so  useful  a  handbook,  which  ought 
to  be  universally  studied  by  medical  men  of  every 
class,  and  made  use  of  by  way  of  reference  by  office 
pupils,  as  a  standard  authority.  It  has  been  much 
enlarged,  and  now  condenses  a  vast  amount  of  need- 
ful and  necessary  knowledge  in  small  compass.  The 
more  of  such  books  the  better  for  the  profession  and 
the  public. — N.  Y.  Med.  Gazette. 

It  is  one  of  the  most  useful  books  a  country  practi- 


tioner can  possibly  have  in  his  possession. — Medical 
Chronicle. 

The  amount  of  useful,  every-day  matter,  for  a  prac- 
tising physician,  is  really  immense. — Boston  Med.  and 
Surg.  Journal. 

This  is  a  work  of  six  hundred  and  fifty-one  pages, 
embracing  all  on  the  subject  of  preparing  and  admi- 
nistering medicines  that  can  be  desired  by  the  physi- 
cian and  pharmaceutist. —  Western  Lancet. 

In  short,  it  is  a  full  and  complete  work  of  the  kind, 
and  should  be  in  the  hands  of  every  physician  and 
apothecary.—  O.  Med.  and  Surg.  Journal. 

We  predict  a  great  sale  for  this  work,  and  we  espe- 
cially recommend  it  to  all  medical  teachers. — Hich- 
mond  Stethoscope. 

This  edition  of  Dr.  Griffith's  work  has  been  greatly 
improved  by  the  revision  and  ample  additions  of  Dr. 
Thomas,  and  is  now,  we  believe,  one  of  the  most  com- 
plete works  of  its  kind  in  any  language.  The  additions 
amount  to  about  seventy  pages,  and  no  effort  has  been 
spared  to  include  in  them  all  the  recent  improvements 
which  have  been  published  in  medical  journals  and 
systematic  treatises.  A  work  of  this  kind  appears  to 
us  indispensable  to  the  physician,  and  there  is  none 
we  can  more  cordially  recommend. — iV.  T.  Journal  of 
Medicine. 


28 


BLANCHARU  AISID  LEA'S 


DUNGLISON'S  THERAPEUTICS— (Just  Issued). 


GENERAL  THERAPEUTICS 

ADAPTED  FOR  A  MEDICAL  TEXT-BOOK. 
BY  ROBLEY  DUNGLTSON,  M.  D., 

Professor  of  Institutes  of  Medicine  in  Jefferson  Medical  College,  Philadelphia. 

WITH  ABOUT 

Two  Hundred   Illustrations. 

SIXTH   EDITION, 

3^cbiscTJ  an"D  JJmjpvobeti. 

I7i  two  very  handsonne  octavo  vo- 
lumes of  about  11 00  pages  ; 
leather,  price  $6. 

The  constant  accessions  to 
the  list  of  remedial  agents, 
and  the  industry  with  which 
investigations  are  daily  made 
in  practical  therapeutics,  ren- 
der a  work  like  this  one  of 
the  most  indispensable  ad- 
juncts to  a  physician's  libra- 
ry. The  industry  of  the  au- 
thor in  bringing  his  works  up 
to  the  day  of  publication,  and 
the  rapid  succession  of  edi- 
tions, which  enables  him  to 
frequently  embody  the  results 
of  the  latest  improvements 
and  discoveries,  is  a  sufficient 
guarantee  that  these  volumes 
will  always  be  found  on  a  level 
with  the  most  advanced  state 
of  the  subject. 
Ricmus  communis  {Castor-Oil  Plant.) 


In  this  work  of  Dr.  Dunglison,  we  recognize  the 
same  untiring  industry  in  the  collection  and  embody- 
ing of  facts  on  the  several  subjects  of  which  he  treats, 
that  has  heretofore  distinguished  him,  and  we  cheer 
fully  point  to  these  volumes  as  two  of  the  most  inte- 
resting that  we  know  of.  In  noticing  the  additions  to 
this  edition,  there  is  verj'  little  in  the  periodical  or 
annual  literature  of  the  profession,  published  in  the 
interval  which  has  elapsed  since  the  issue  of  the  first, 
that  has  escaped  the  careful  search  of  the  author.  As 
a  book  for  reference,  It  is  invaluable. — CharUsion 
Medical  Journal  and  Review. 

It  may  be  said  to  be  the  work  now  upon  the  subjects 
upon  which  it  treats. —  Western  Lancet. 


The  most  complete  and  satisfactory  exponent  of  the 
existing  state  of  Therapeutical  Science,  within  the 
moderate  limits  of  a  text-book,  of  any  hitherto  pub- 
lished. What  gives  the  work  a  superior  value,  in  our 
judgment,  is  the  happy  blending  of  Therapeutics  and 
Materia  Medica  as  they  are  or  ought  to  be  taught  in  all 
our  Medical  schools;  going  no  further  into  the  nature 
and  commercial  history  of  drugs  than  is  indispensable 
for  the  medical  student.  This  gives  to  the  treatise  a 
clinical  and  practical  character,  calculated  to  benefit, 
in  the  highest  degree,  both  students  and  practitioners. 
We  shall  adopt  it  as  a  text-book  for  our  classes,  while 
pursuing  this  branch  of  medicine,  and  shall  be  happy 
to  learn  that  it  has  been  adopted  as  such  in  all  of  our 
medical  institutions. — The  N.  Y.  Journal  of  Medicine. 


A  DISPENSATORY  AND  THERAPEUTICAL  REMEMBRANCER,  Comprising  the  entire 
lists  of  Materia  Medica,  with  every  Practical  Formula  contained  m  the  three  British  Pharma- 
copoeias. By  John  Mayne,  M.  D.,  M.  R.  C.S  Edited,  with  the  addition  of  the  Formulse 
of  the  United  States  Pharmacopoeia,  by  R.  Eglesfeld  Griffith,  M.  D.  In  one  12mo. 
volume,  extra  cloth,  of  over  300  large  pages,  cloth,  75  cents. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS.  29 

A  NEW  AND  COMPLETE  THERAPEUTICAL  TEXT-BOOK— (To  be  ready  in  the  autumn.) 

THERAPEUTICS  AND~MATERIA  MEDICA: 

A  SYSTEMATIC  TREATISE  ON  THE 

HISTORY,  DESCRIPTION,  ACTIONS,  AND  USES  OF  MEDICINAL  AGENTS. 

BY  ALFRED  STILLE,  M.  D., 

Late  Professor  of  the  Theory  and  Practice  of  Medicine  in  the  Pennsylvania  Med.  College. 
In  two  large  and  handsome  octavo  volumes  of  over  1500  pages. 

The  object  which  the  author  has  kept  in  view  in  the  preparation  of  this  work  has  been  to 
present  to  the  profession  a  complete  and  sy^tel■natlc  treatise  suited  to  the  wants  o(  the  practising 
physician.  He  has  therefore  endeavored  to  avoid  encumbering  his  text  with  details  interesting 
only  to  the  naturalist  or  the  dealer,  and  has  sought  to  give  in  ihe  history  and  description  of  drugs 
such  information  only  as  would  be  required  by  the  intelligent  practitioner.  The  space  thus 
gained  he  has  endeavored  to  till  with  a  complete  account  of  the  physiological  and  therapeutic 
properties  of  all  ihe  articles  of  the  Materia  Medica,  their  u-es  in  all  the  varieties  of  di^ease, 
their  pharmacopoeial  preparations,  and  the  mode  in  which  they  may  be  most  succes?fully  em- 
ployed. The  subject  of  General  Therapeutics  will  be  fognd  more  fully  developed  than  is  cus- 
tomary in  works  of  this  nature;  but  while  general  principles  will  be  careluUy  enunciated  and 
developed,  mere  theoretical  speculations  will  be  avoided.  The  labor  of  many  years  devoted  to 
the  work  has  enabled  the  author  to  accumulate  and  record  the  results  of  the  experience  of  the 
highest  authorities  in  all  countries,  and  his  watchful  care  in  incorporating  the  latest  observations 
and  researches  is  a  guarantee  that  the  whole  will  be  found  fully  brought  up  to  the  day,  with  all 
that  may  be  regarded  as  worthy  of  confidence. 

The  work  is  therefore  presented  as  a  practical  companion  for  the  active  physician  who  may 
desire  to  keep  himself  on  a  level  with  the  advance  of  his  profession,  as  well  as  a  text-book  for 
the  student  entering  upon  his  medical  education.  The  long  delay  which  has  occurred  in  its 
appearance  ha>  been  caused  by  the  determination  of  the  author  to  spare  no  pains  in  rendering 
it  complete  on  every  point :  it  is  now,  however,  proceeding  rapidly  through  the  press,  and  the 
publisliers  expect  to  have  it  in  readiness  lor  the  fall  sei^sions  of  the  medical  schools. 


A  COMPLETE  ENCYCLOPEDIA  OP  MATERIA  MEDICA. 

THE 

ELEMENTS  OF  MATERIA  MEDICA  AM  THERAPEUTICS. 

BY  JONATHAN  PEREIRA,  M.  D.,  F.  R.  S.,  &c. 
2[f)trTi  gimerfcan  HDitioit,  lenlavfletr  anU  fimprobeTi  Ijb  Hje  Slutljor. 

INCLUDING 

NOTICES  OF  MOST  OF  THE  MEDICINAL  SUBSTANCES  IN  USE  IN  THE  CIVILIZED  WORLD, 

AND  FORMING  AN 

ENCYCLOPEDIA   OF  MATERIA  MEDICA. 

Edited  by  JOSEPH  CARSON,  M.  D., 
Professor  of  Materia  Medica  and  Pharmacy  in  the  University  of  Pennsylvania,  &c. 

hi  two  very  large  octavo  volumes  q/"2100  pages,  hi  small  type,  with  over  450  illustrations, 
strongly  hound  in  leather,  with  raised  hands,  price  §9. 

The  Second  Volume  will  no  longer  be  sold  separate. 


MEDICAL   BOTANY; 

OR, 

DESCRIPTIONS  OF  THE  MORE  IMPORTANT  PLANTS  USED  IN  MEDICINE, 
With  their  History,  Properties,  and  Modes  of  Administration. 

By  R.  EGLESFELD  GRIFFITH,  M.  D., 

Author  of  "A  Universal  Formulary,"  &c. 

WITH  UPWARDS   OF  THREE  HUNDRED  ILLUSTRATIONS. 

In  one  large  and  very  handsome  octavo  volume  of  100  pages ;  extra  cloth,  price  $3. 


30 


BLANCHARD  AND  LEA'S 


MATERIA  MEDICA  AND  THERAPEUTICS. 

INCLUDING  THE  PREPARATIONS  OF 

THE  PHARMACOPCEIAS  OF  LONDON,  EDINBURGH,  DUBLIN, 
AND  OF  THE  UNITED  STATES. 

WITH    MANY    NEW    MEDICINES. 

By  J.  FORBES  BOYLE,  M.D.,F.R.S.,  &c. 

Edited  BY  JOSEPH  CARSON,  M.D., 

Professor  of  Materia  Medica  and  Pharmacy  in  the  University  of  Pennsylvania,  &c. 


In  one 

very  handsome  octavo  volume 

of  nearly 

seven  hundred  pages, 

with  about  one  hundred 

beautiful  illustrations  on  wood. 

Extra  cloth,  price  $3. 


Senna  and  its  Adulterations. 

This  work  is,  indeed,  a  most  valuable  one,  and  will 
fill  up  an  important  vacancy  that  existed  between  Dr. 
Pereira's  most  learned  and  complete  system  of  Mate- 


ria Medica,  and  the  class  of  productions  on  the  other 
extreme,  which  are  necessarily  imperfect  from  their 
small  extent. — British  and  Foreign  Medical  Review. 


Ne-vr  and  Revised  Edition. 

SYNOPSIS  OF  THE  COURSE  OF  LECTURES  ON  MATERIA  MEDICA  AND  PHAR- 
MACY, delivered  in  the  University  of  Pennsylvania.  By  Joseph  Carson,  M.  D.,  Professor 
of  Materia  Medica  and  Pharmacy  in  the  University  of  Pennsylvania.  Second  edition,  revised. 
In  one  very  neat  octavo  volume,  of  208  pages,  cloth,  f  1  50. 

THE  THREE  KINDS  OF  COD-LIVER  OIL,  comparatively  considered,  with  their  Chemical 
and  Therapeutic  properties.     By  D.  L.  De  Jongh,  M.  D.     12mo.,  extra  cloth,  75  cents. 

CABPENTER  ON  THE  USE  OF  ALCOHOLIC  LIQUORS  IN  HEALTH 

AND  DISEASE.     'New  edition,  with  a  Preface  by  D.  F.  Condie,  M.  D.     In  one  neat  12mo. 
volume,  extra  cloth,  pp  178.     {Just  Issued.)    50  cents. 


THE  MEDICAL  FORMULARY;  being  a  collection  of  Prescriptions,  derived 
from  the  Writings  and  Practice  of  many  of  the  most  eminent  Physicians  of  America  and 
Europe :  together  with  the  usual  Dietetic  Preparations  and  Antidotes  for  Poisons.  To  which 
is  added  an  Appendix,  on  the  Endermic  Use  of  Medicines,  and  on  the  uses  of  Ether  and  Chlo- 
roform. The  whole  accompanied  with  a  few  brief  Pharmaceutic  and  Medical  observations. 
By  Benjamin  Ellis,  M.  D.  Tenth  edition,  revised  and  much  extended,  by  Robert  P.  Tho- 
mas. M.  D.,  Professor  of  Materia  Medica  in  the  Philadelphia  College  of  Pharmacy,  &c.  In 
one  neat  octavo  volume,  extra  cloth,  of  three  hundred  pages,  price  $1  75. 


After  an  examination  of  the  new  matter  and  the 
alterations,  we  believe  the  reputation  of  the  work 
built  up  by  the  author,  and  the  late  distinguished 
editor,  will  continue  to  flourish  under  the  auspices  of 
the  present  editor,  who  has  the  industry  and  accuracy, 
and,  we  would  say,  conscientiousness  requisite  for  the 
responsible  task, — Ameriwn  Journal  of  Pharmacy. 


It  will  prove  particularly  useful  to  students  and 
young  practitioners,  ss  the  most  important  pre.scrip- 
tions  employed  in  modern  practice,  which  lie  scattered 
through  our  medical  literature,  are  here  collected  and 
conveniently  arranged  for  reference. — Charleston  Med. 
Journal  and  Review. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


31 


New  and  Enlarged  Edition — (Just  Issued.) 

IST  E  W^     R  EM  E  D  I  E  S  : 

WITH  FORMUIJ]  FOR  THEIR  PREPARATION  AND  ADMINISTRATION. 
BY  ROBLEY  DUNOLISON,  M.  D., 

Professor  of  the  InslitiUes  of  Medicine,  &c.  ia  the  Jefferson  Medical  College,  Philadelphia. 

Seventh  Edition,  with  extensive  Additions. 

In  one  very  targe  octavo  volume  of  IIQ  pages,  leather,  $3  75. 

As  the  value  of  a  work  sucih  as  the  present  is  greatly  enhanced  by  the  thoroughness  with 
which  all  the  latest  improvements  and  discoveries  are  embodied  in  its  pages,  the  author  has 
spared  no  pains  in  preparing  the  present  edition  to  render  it  a  complete  exposition  of  the  most 
recent  aspect  of  therapeutic  science.  A  large  number  of  additional  articles  have  been  introduced, 
and  many  of  the  older  ones  have  been  rewritten  to  adapt  them  to  the  present  condition  of  the 
subject.  A  very  considerable  increase  in  the  size  of  the  page  has  accommodated  these  additions 
without  unduly  swelling  the  bulk  of  the  volume,  and  it  is  confidently  presented  as  in  every 
respect  worthy  a  continuance  of  the  very  great  favor  which  it  has  thus  far  received. 


This  new  and  much  enlarged  edition  of  Dr.  Dungli- 
pon's  very  valuable  work  will  be  welcomed  by  the  pro- 
fession already  well  acquainted  with  its  merits.  The 
Tast  research  and  thorough  information  which  the 
author  has  brought  to  the  execution  of  his  labors,  aie 
evident  upon  every  page;  and  he  is  entitled  to  the 
hearty  thanks  of  his  brethren  for  this  and  the  many 
other  good  things  which  he  has  done.  Few  would 
willingly  be  without  this  excellent  volume  who  desire 
not  only  to  know  "  new  remedies"  thoroughly,  but 
also  to  test  their  efficacy. — Boston  Med.  and  Surg. 
Journal,  Aug.  1856. 

It  may  be  considered  almost  a  work  of  supereroga- 
tion to  enter  Into  an  elaborate  criticism  of  a  work 
■which  has  reached  its  se.re.nth  edition.  The  public  has 
pronounced  in  the  most  authoritative  manner  its  ver- 
dict, and  we  are  cerlainly  not  disposed  in  the  present 
instance  to  dispute  its  decision.  In  truth,  such  books 
a.«  this  will  always  be  favorably  received  by  the  pro- 
fession of  our  country.  They  are  labor-saving  pro- 
ductions, which,  at  the  expense  of  much  research  and 


reading  to  the  author,  condense  in  a  convenient  space 
the  novelties  and  discoveries  of  the  age.  The  present 
edition  of  this  work  is  considerably  enlarged  and  im- 
proved. The  author,  with  his  accustomed  accuracy, 
has  elaborated  and  ampliiied  many  of  the  articles  but 
casually  or  imperfectly  treated  of  in  the  former  edi- 
tions ;  and  he  has  also  added  considerably  to  the  list 
of  new  remedies.  Abiut  thirty  new  agents  or  novel 
applications  of  old  remedies  are  introduced  to  the 
notice  of  the  readerln  this  edition. — Va.  Med.  o.nd  Surg. 
Journal,  Sept.  1S56. 

As  a  work  of  reference  upon  all  new  remedies,  this 
is  one  of  the  most  complete  with  which  we  are  ac- 
quainted. The  quotations  of  authorities  are  extensive, 
minute,  and  carefully  given;  and  we  are  satisfied  that 
no  medical  man  would  regret  following  our  advice  to 
acquire  it,  as  daily  opportunities  will  occur  in  which 
he  may  both  test  its  value  and  increase  his  own  know- 
ledge, in  searching  for  the  practical  information  it 
affords. — British  and  Foreign  Med.-Chirurgical  Review, 
July,  1857. 


A.    n3ISI^ENS.A.TOIl  Y; 


Commentary  on  the  Plmrmacopceias  of  Great 
Britain  and  the  United  States : 

COMPRISING  THE 

Natural  History,   Description,  Chemistry,  Phar- 
macy, Action,  Uses,  and  Doses  of  the 
Articles  of  the  Materia  Medica. 

BY 

R.V.CHRISTISON.M.D.,V.P.R.S.E.,&c. 

SECOND  EDITION,  REVISED  AND  IMPROVED. 

WITH  A   SUPPLEMENT 

Containing  the  most  important  New  Remedies, 

WITH  COPIOUS  ADDITIONS 

BY  R.  EGLESFELD  GRIFFITH,  M.D. 

In  one  very  latge  and  handsome  octavo  volume  of  over 

1000 pages,  with  213  engravings  on  wood; 

leather,  price  $3  50. 

It  is  not  needful  that  we  should  compare  it  with  the 
other  pharmacopoeias  extant,  which  enjoj'  and  merit 
the  confidence  of  the  profession :  it  is  enough  to  say 
that  it  appears  to  us  as  perfect  as  a  Dispensatory,  in 
the  present  state  of  pharmaceutical  science,  could  he 
made.  If  it  omits  any  details  pertaining  to  this  branch 
of  knowledge  which  the  student  has  a  right  to  expect 
in  such  a  work,  we  confess  the  omission  has  escaped 
our  scrutiny.  We  cordially  recommend  this  work  to 
such  of  our  readers  as  are  in  need  of  a  Dispensatory. 
They  cannot  make  choice  of  a  better.  —  Western  Jour- 
nal of  Medicine  and  Surgery. 

There  is  not  in  any  language  a  more  complete  and 
perfect  Treatise. — iVew  Ycrrk  Annalist. 


Aronitum  napeltux. 


32 


BLANCHARD  AND  LEA'S 


THE  GREAT  LIBRARY  OF  PATHOLOGY— (Just  Issued.) 


Complete  in 

four  handsome  octavo  volumes 

bound  in  two, 

containing  about 

twelve  hundred  and  fifty  large  pages; 

extra  cloth, 

price    $5   50. 


Medullary  Carcinu?na. 

A  MANUAL  OF  PATHOLOGICAL  ANATOMY. 

BY  CARL  ROKITANSKY,  M.  D., 

Curator  of  the  Imperial  Pathological  Museum  and  Professor  at  ihe  University  of  Vienna. 

Vol.  I  —Manual  of  General  Pathological  Anatomy.     Translated  by  W.  E.  Swaine. 

Vol.  II.— Pathological  Anatomy  of  the  Abdominal  Viscera.     Translated  by  Edward  Sieveking, 

M.D. 
Vol.  III.— Pathological  Anatomy  of  the  Bones,  Cartilages,  Muscles,  and  Skin,  Cellular  and 

Fibrous  Tissues,  Serous  and  Mucous  Membrane,  and  Nervous  System.     Translated  by  C. 

H.  MooRE. 
Vol.  IV. — Pathological  Anatomy  of  the  Organs  of  Respiration  and  Circulation.     Translated  by 

G.  E.  Day,  M.  D. 
To  render  this  large  and  important  work  more  easy  of  reference,  and  at  the  same  time  less  cum- 
brous and  costly,  the  four  volumes  have  been  arranged  in  two,  retaining,  however,  the  sepa- 
rate paging,  &c. 

The  publishers  feel  much  pleasure  in  presenting  to  the  profession  of  the  United  Slates  the 
great  work  of  Prof.  Rokitansky,  which  is  universally  referred  to  as  the  standard  of  authority  by 
the  pathologists  of  all  nations.  Under  the  auspices  of  the  Sydenham  Society  of  London,' the 
combined  labor  of  four  translators  has  at  length  overcome  the  almost  insuperable  difficulties 
which  have  so  long  prevented  the  appearance  of  the  work  in  an  English  dress,  while  the  addi- 
tions made  from  various  papers  and  essays  of  the  author  present  his  views  on  all  the  topics  em- 
braced, in  their  latest  published  form.  To  a  work  so  widely  known,  eulogy  is  unnecessary,  and 
the  publishers  would  merely  state  that  it  is  said  to  contain  the  results  of  not  less  than  thirty 
THOVSAND  post-morte7n.  examinations  made  by  the  author,  diligently  compared,  generalized,  and 
wrought  into  one  complete  and  harmonious  system. 


The  profession  is  too  well  acquainted  with  the  re- 
putation of  Roliitansky's  work  to  need  our  assurance 
that  this  is  one  of  the  most  profound,  thorough,  and 
valuable  hooks  ever  issued  from  the  medical  press. 
It  is  SMI  fifeneris,  and  has  no  standard  of  comparison. 
It  is  only  necessary  to  announce  that  it  is  issued  in  a 
form  as  cheap  as  is  compatible  with  its  size  and  pre- 
servation, and  its  sale  follows  as  a  matter  of  course. 
No  library  can  be  called  complete  without  it. — Bvffalo 
Med.  Journal. 

An  attempt  to  give  our  readers  any  adequate  idea 
of  the  vast  amount  of  instruction  accumulated  in 
these  volumes,  would  be  feeble  and  hopeless.  The 
effort  of  the  distinguished  author  to  concentrate  into 
a  small  space  his  great  fund  of  knowledge,  has  so 
charged  his  text  with  valuable  truths,  that  any  at- 
tempt of  a  reviewer  to  epitomize  is  at  once  paralyzed, 
and  must  end  in  a  failure. —  Western  Lancet. 

As  a  hook  of  reference,  therefore,  this  work  must 
prove  of  inestimable  value,  and  we  cannot  too  highly 
recommend  it  to  the  profession. —  Charleston  Med. 
Journal  and  Review. 

This  book  is  a  necessity  to  every  practitioner. — Am. 
Med.  Monthly, 


The  attempt  to  give  our  readers  any  adequate  idea 
of  the  vast  storehouse  of  knowledge  contained  in  these 
volumes  we  feel  to  be  utterlj'  hopeless.  The  patient 
labors  of  nearly  thirty  years  in  a  field  so  vast  as  almost 
to  pass  beyond  our  comprehension  ;  the  accurate  dis- 
sections made  on  more  than  thirty  thousand  human 
bodies  are  here  carefully  noted  ;  and  the  whole  power 
of  a  vigorous  and  practical  mind  has  been  concentrated 
upon  its  execution.  To  the  student  of  disease  in  its 
very  formation,  and  in  its  endless  variety  of  develop- 
ment; to  the  investigators  of  the  true  causes  of  symp- 
toms, and  the  many  phenomena  displayed  at  the  bed- 
side; to  all  who  strive  to  build  up  a  sound  and  dis- 
creet method  of  treatment,  based,  as  it  must  always 
be,  on  an  accurate  acquaintance  with  the  pathological 
conditions  of  each  case:  we  recommend  this  noble 
work  as  containing  in  itself  everything  which  is 
needed  to  the  fullest  comprehension  of  the  subject. — 
Va.  Med.  and  Surg.  Journal. 

It  is,  everywhere,  in  fact,  acknowledged  to  be  fore- 
most and  unrivalled  in  its  department.  Only  the  most 
earnest  professional  ardor,  the  most  persevering  labor, 
could  have  enabled  its  author  to  amass  the  immense 
amount  of  information  contained  in  its  pages. — Medi- 
cal Examiner. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


33 


New  and  thoroughly  Revised  Edition — (Just  Issued.) 

ELEMENTS  OF  PATHOLOGICAL  ANATOMY. 

BY  SAMUEL  D.  GROSS,  M.  D., 

Professor  of  Surgery  in  the  Jefferson  Medical  College,  Philadelphia. 

Third  Edition,  Modified  and  thoroughly  Revised, 

ILLUSTRATED  BY  THREE  HUNDRED  AND  FORTY-TWO  ENGRAVINGS  ON  WOOD. 


In  one 

large  and  very  handsome 

octavo  volume, 

of  nearly  800  pages. 

Price, 
in  extra  cloth,  $4  75; 

leather, 
raised  bands,  $5  25. 


Keloid  growth  of  the  Face. 

The  very  rapid  advances  in  the  Science  of  Pathological  Anatomy  during  the  last  few  years 
have  rendered  essential  a  thorough  modification  of  this  work,  with  a  view  of  making  it  a  correct 
exponent  of  the  present  state  of  the  subject.  The  very  careful  manner  in  which  this  task  has 
been  executed,  and  the  amount  of  alteration  which  it  has  undergone,  have  enabled  the  author 
to  say  that  "with  the  many  changes  and  improvements  now  introduced,  the  work  majr  be  re- 
garded almost  as  a  new  treatise,"  while  the  efforts  of  the  author  have  been  seconded  as  regards 
the  mechanical  execution  of  the  volume,  rendering  it  one  of  the  handsomest  productions  of  the 
American  press.  A  very  large  number  of  new  and  beautiful  original  illustrations  have  been 
introduced,  and  the  work,  it  is  hoped,  will  fully  maintain  the  reputation  hitherto  enjoyed  by  it 
of  a  complete  and  practical  exposition  of  its  difficult  and  important  subject. 


We  most  sincerely  congratulate  the  author  on  the 
successful  manner  in  which  he  has  accomplished  his 
proposed  object.  His  book  is  most  admirably  calcu- 
lated to  fill  up  a  blank  which  has  long  been  felt  to 
exist  in  this  department  of  medical  literature,  and  as 
such  must  become  very  widely  circulated  amongst  all 
classes  of  the  profession. — Dublin  Quarterly  Journ.  of 
Med.  Science,  Nov.  1857. 


We  have  been  favorably  impressed  with  the  general 
manner  in  which  Dr.  Gross  has  executed  his  task  of 
affording  a  comprehensive  digest  of  the  present  state 
of  the  literature  of  Pathological  Anatomy,  and  have 
much  pleasure  in  recommending  his  work  to  our  read- 
ers, as  we  believe  one  well  deserving  of  diligent  pe- 
rusal and  careful  study. — Montreal  Med.  Chron.,  Sept. 
1857. 


ATLAS  OF  PATHOLOGICAL  HISTOLOGY. 

BY  GOTTLEIB  GLtJGB,  M.  D., 

Professor  of  Physiology  and  Pathological  Anatomy  in  the  University  of  Brussels,  &c. 
TRANSLATED,     WITH    NOTES    AND     ADDITIONS, 

BY  JOSEPH  LEIDY,  M.  D., 

Professor  of  Anatomy  in  the  University  of  Pennsylvania,  &c. 

In  one  handsoine  volume,  large  imperial  quarto,  with  320  Figures,  plain  and  colored, 
on  twelve  copperplate  engravings,  price  $5  00. 


This  being,  as  far  as  we  know,  the  only  work  in 
which  pathological  histology  is  separately  treated  of 
in  a  comprehensive  manner,  it  will,  we  think,  for  this 
reason,  be  of  infinite  service  to  those  who  desire  to 
investigate  the  subject  systematically,  and  who  have 
felt  the  difficulty  of  arranging  in  their  minds  the  un- 

3 


connected  observations  of  a  great  number  of  authors. 
The  development  of  the  morbid  tissues,  and  the  format 
tion  of  abnormal  products,  may  now  be  followed  and 
studied  with  the  same  ease  and  satisfaction  as  the  best 
arranged  system  of  Physiology. — American  Medical 
Journal. 


34 


BLANCHARD    AND    LEA'S 


PATHOLOGICAL  MANUAL- (Lately  Published.) 


Pyelitis. 


Fibrinous  Deposits  in  Granular  Kidney. 


A  MANUAL  OF  PATHOLOGICAL  ANATOMY. 

BY  C.  HANDFIELD  JONES,  M.  D.,  F.  E.  S., 

Lecturer  on  Physiology  at  St.  Mary's  Hospital,  &c. 

AND 

EDWARD   H.  SIEVEKING,  M.  D., 

Lecturer  on  Materia  Medica  at  St.  Mary's  Hospital. 

FIRST    AMERICAN    EDITION,    REVISED. 

With  three  hundred  and  ninety-seven  Engravings  on  "Wood. 

Li  one  large  and  very  handsome  octavo  volume  of  seven  hundred  and  thirty-four  pages, 

leather,  $3  75. 

As  a  concise  text-book,  containing,  in  a  condensed  form,  a  complete 
outline  of  what  is  known  in  the  domain  of  Pathological  Anatomy,  it 
is  perhaps  the  hest  work  in  the  English  language.  Its  great  merit 
consists  in  its  completeness  and  brevity,  and  in  this  respect  it  supplies 
a  great  desideratum  in  our  literature.  Heretofore  the  student  of 
pathology  was  obliged  to  glean  from  a  great  number  of  monographs, 
and  the  field  was  so  extensive  that  but  few  cultivated  it  with  any  de- 
gree of  success.  The  authors  of  the  present  work  have  sought  to 
correct  this  defect  by  placing  before  the  reader  a  summary  of  ascer- 
tained facts,  together  with  the  opinions  of  the  most  eminent  patho- 
logists both  of  the  Old  and  New  World.  As  a  simple  work  of  reference, 
therefore,  it  is  of  great  value  to  the  student  of  pathological  anatomy, 
and  should  be  in  every  physician's  library. —  Western  Lancet. 

AYe  urge  upon  our  readers  and  the  profession  generally  the  import- 
ance of  informing  themselves  in  regard  to  modern  views  of  pathology, 
and  recommend  to  them  to  procure  the  work  before  us  as  the  best 
means  of  obtaining  this  information. — Stethoscope. 

In  offering  the  above  titled  work  to  the  public,  the  authors  have 
not  attempted  to  intrude  new  views  on  their  professional  brethren, 
but  simply  to  lay  before  them,  what  has  long  been  wanted,  an  outline 
of  the  present  condition  of  pathological  anatomy.  In  this  they  have 
been  completely  successful.  The  work  is  one  of  the  best  compila- 
tions which  we  have  ever  perused.  The  opinions  and  discoveries  of 
all  the  leading  pathologists  and  physiologists  are  engrossed,  so  that 
by  reading  any  subject  treated  in  the  book  you  have  a  .synopsis  of  the 
views  of  the  most  approved  authors. — Charleston  Medical  Journal 
and  Review. 

We  have  no  hesitation  in  recommending  it  as  worthy  of  careful 
and  thorough  study  by  every  member  of  the  profession,  old  or  young. 
— N.  W  Med.  and  Surg.  Journal. 

to  be  largely  useful,  as  it  suits  itself  to  those  busy  m  en 
who  have  little  time  for  minute  investigation,  and 
prefer  a  summary  to  an  elaborate  treatise. — Buffalo 
Medical  Journal. 


Osteophytes  in  lower  end  of  Femur. 


From  the  casual  examination  we  have  given  we  are 
inclined  to  regard  it  as  a  text-book,  plain,  rational,  and 
intelligible,  such  a  book  as  the  practical  man  needs 
for  daily  reference.    For  this  reason  it  will  be  likely 


GENERAL   PATHOLOGY; 

As  Conducive  to  the  Establishment  of  Rational  Principles  for  the  Prevention  and  Cure  of  Dis- 
ease.    A  Course  of  Lectures  delivered  at  St.  Thomas's  Hospital.    By  John  Simon,  F.  R.  S 
&c.    In  one  neat  octavo  volume,  extra  cloth,  $1  25. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


35 


BARCLAY  ON  DIAGNOSIS— A  New  Work,  Now  Ready  (1858). 

A  MANUAL  OF  MEDICAL  DIAGNOSIS; 

be™  an  analysis  of  the  signs  and  symptoms  of  disease. 

By  a.  W.  BARCLAY,  M.  D., 

Assistant  Physician  to  St.  George's  Hospital,  &o. 
Ill  one  neat  octavo  volume  of  424  pages  ;  extra  cloth,  price  f  2. 


Of  works  exclusively  devoted  to  this  important 
branch,  our  profession  has  at  command,  comparative- 
ly, hut  few,  and  therefore,  in  the  publication  of  the 
present  work,  Messrs.  Blanchard  &  Lea  have  conferred 
a  great  favor  upon  us.  Dr.  Barclay,  from  having  occu- 
pied, for  a  long  period,  the  position  of  Medical  Regis- 
trar at  St.  George's  Hospital,  possessed  advantages  for 
correct  observation  and  reliable  conclusions,  as  to  the 
significance  of  symptoms,  which  have  fallen  to  the  lot 
of  but  few,  either  in  his  own  or  any  other  country. 
He  has  carefully  systematized  the  results  of  his  ob- 
servation of  over  twelve  thousand  patients,  and  by  his 
diligence  and  judicious  classification,  the  profession 
has  been  presented  with  the  most  convenient  and  re- 
liable work  on  the  subject  of  Diagnosis  that  it  has 
been  our  good  fortune  ever  to  examine;  we  can,  there- 
fore, say  of  Dr.  Barclay's  work,  that  from  his  system- 
atic manner  of  arrangement,  his  work  is  one  of  the 
best  works  "  for  reference"  in  the  daily  emergencies 
of  the  practitioner,  with  which  we  are  acquainted; 
but,  at  the  same  time,  we  would  recommend  our  read- 
ers, especially  the  younger  ones,  to  read  thoroughly 
and  study  diligently  the  whole  work,  and  the  '•'  emer- 
gencies" will  not  occur  so  often. — Southern  Med.  and 
Surg.  Journal,  March,  1S58. 

To  give  this  information,  to  supply  this  admitted 
deficiency,  is  the  object  of  Dr.  Barclay's  Manual.  The 
task  of  composing  such  a  work  is  neither  an  easy  nor 
a  light  one:  but  Dr.  Barclay  has  performed  it  in  a 
manner  which  meets  our  most  unqualified  approba- 
tion. He  is  no  mere  theorist;  he  knows  his  work  tho- 
roughly, and  in  attempting  to  perform  it,  has  not  ex- 
ceeded his  powers. — British  Med.  Journal,  Dec.  5, 1867. 

We  venture  to  predict  that  the  work  will  be  deserv- 
edly popular,  and  soon  become,  like  Watson's  Practice, 
an  indispensable  necessity  to  the  practitioner. — iV".  O. 
Med.  Journal,  April,  1858. 

An  inestimable  work  of  reference  for  the  young 
practitioner  and  student. — Nashville  Medical  Journal, 
May,  1858. 

We  hope  the  volume  will  have  an  extensive  circula- 
tion, not  among  students  of  medicine  only,  but  prac- 
titioners also.  They  will  never  regret  a  faithful  study 
of  its  pages. — Cincinnati  Lancet,  March,  1858. 


This  Manual  of  Medical  Diagnosis  is  one  of  the  most 
scientific,  useful,  and  instructive  works  of  its  kind  that 
we  have  ever  read,  and  Dr.  Barclay  has  done  good  ser- 
vice to  medical  science  in  collecting,  arranging,  and 
analyzing  the  signs  and  symptoms  of  so  many  dis- 
eases.—iV.  J.  Med.  and  Surg.  Reporter,  March,  1858. 

We  hail  the  appearance  of  this  valuable  book,  com- 
ing to  us  in  its  present  exceedingly  neat  style,  as  an 
important  acquisition  to  medical  literattire.  It  is  a 
work  of  high  merit,  both  from  the  vast  importance  of 
the  subject  upon  which  it  treats,  and  also  from  the 
real  ability  displayed  in  its  elaboration.  In  conclu- 
sion, let  us  bespeak  for  this  volume  that  attention  of 
every  student  of  our  art  which  it  so  richly  deserves — 
that  place  in  every  medical  library  which  it  can  so 
well  adorn. — T!ie  Peninsular  and  Independent  Medical 
Journal,  Sept.  1858. 

Restricted  as  we  are  to  certain  limits,  we  can  hardly 
do  more  than  give  this  brief  synopsis,  which  will  serve, 
however,  to  convey  to  the  reader  an  idea  of  the  scope 
and  the  number  and  variety  of  diagnostic  details  of 
Dr.  Barclay's  volume.  It  was  much  wanted,  and  is 
full  of  instruction  on  a  branch  of  pathology  which 
furnishes  we  will  not  say  the  only,  but  certainly  the 
chief  and  the  safest,  indications  for  the  treatment  of 
disease. — N.  A.  Medico-Chir.  Review,  May,  1858. 

We  conclude  by  assuring  the  honest  and  earnest 
student  who  has  acquainted  himself  sufficiently  with 
the  principles  of  physiology  and  the  details  of  anato- 
my, that  he  could  not  better  aid  or  advance  his  clinical 
investigations,  than  by  carrying  this  work  with  him 
to  the  bedside  of  his  patients,  and  the  junior  practi- 
tioner will  find  much  in  its  small  compass  to  repay  a 
careful  and  perhaps  repeated  perusal. —  Charleston, 
Med.  Journal  and  Review,  May,  1858. 

The  author  writes  with  a  confidence  which  severe 
and  careful  study  can  alone  justify.  There  is  a  full 
table  of  contents,  and  a  most  copious  index,  which  in 
such  a  work  is  invaluable.  In  conclusion,  we  can  ho- 
nestly recommend  this  work  to  the  profession — to  the 
junior  members  of  it  as  a  handbook  of  study;  to  the 
seniors,  as  a  useful  compendium  of  things  to  be  re- 
membered in  cases  of  obscurity. — Medical  Times  and 
Gazette,  London,  Nov.  14, 1857. 


CYCLOP J]DIA  OF  PRACTICAL  MEDICIM; 

COMPRISING 

Treatises  on  the  Nature  and  Treatment  of  Diseases,  Materia  ledica  and  Therapeutics, 
Diseases  of  Women  and  Children,  Medical  Jurisprudence,  &c.  &c. 

EDITED    BY 

JOHN  FORBES,  M.D.,  F.  R.  S.,  ALEXANDER  TWEEDIE,  M.  D.,  F.  R.  S., 

AND  JOHN  CONNOLLY,  M.  D. 

Revised,  with  Additions, 

BY  ROBLEY  DUNGLISON,  M.  D. 

COMPLETE,  IN  FOUR  LARGE  SUPER-ROYAL  OCTAVO  VOLUMES. 

Containing  thirty-two  hundred  and  fifty-four  unusually  large  pages,  in  doiible  cokimiis, 
printed  on  good  paper,  vnth  a  new  and  clear  type. 

•  THE  WHOLE  WELL  AND  STRONGLY  BOUND  IN  LEATHER,  WITH  RAISED  BANDS  AND  DOUBLE  TITLES.      Price  $12  00. 

This  work  contains  no  less  than  TOUR  HUNDRED  AND  EIGHTEEN  DISTINCT  TREATISES, 

By  Sixty-eight  Distinguished  Physicians. 


The  most  complete  work  on  Practical  Medicine  ex- 
tant ;  or,  at  least,  in  our  language. — Buffalo  Medical 
and  Surgical  Journal. 


For  reference,  it  is  above  all  price  to  every  practi- 
tioner.— Western  Lancet. 


36 


BLANCHARD  AND  LEA'S 


New  and  Much  Improved  Edition. 

PRINCIPLES  OF  MEDICINE. 

AN  ELEMENTARY  VIEW  OF  THE  CAUSES,  NATURE,  TREATMENT, 
DIAGNOSIS  AND  PROGNOSIS  OF  DISEASE, 

WITH  BRIEF  REMARKS  ON  HYGIENICS,  OR  THE  PRESERVATION  OF  HEALTH. 

BY  CHARLES  J.  B.  WILLIAMS,  M.D.,F.R.S. 

A  new  American,  from  the  Third  and  Revised  Liondon  Edition. 

In  0716  neat  octavo  volume,  of  about  five  hundred  large  pages,  leather,  $2  50. 

The  very  recent  and  thorough  revision  which  this  work  has  enjoyed  at  the  hands  of  (he  au- 
thor has:  brought  it  so  completely  up  to  the  present  stale  of  the  subject  that  in  reproducing  it  no 
additions  have  been  found  neces^sary.  The  success  which  the  work  has  heretofore  met  shows 
that  its  importance  has  been  appreciated,  and  in  its  present  form  it  will  be  found  eminentl}'  wor- 
thy a  continuance  of  the  same  favor,  possessing  as  it  does  the  strongest  claims  to  the  attention 
of  the  medical  student  and  practitioner,  from  the  admirable  manner  in  which  the  various  inqui- 
ries in  the  different  branches  of  pathology  are  investigated,  combined,  and  generalized  by  an 
experienced  practical  physician,  and  directly  applied  to  the  investigation  and  treatment  of  disease. 


We  find  that  the  deeply-interesting  matter  and  style 
of  this  book  have  so  far  fascinated  us,  that  we  have 
unconsciously  hung  upon  its  pages,  not  too  long,  in- 
deed, for  our  own  profit,  but  longer  than  reviewers 
can  be  permitted  to  indulge.  We  leave  the  further 
analysis  to  the  student  and  practitioner.  Our  judg- 
ment of  the  work  has  already  been  sufficiently  ex- 
pressed. Itis  a  judgment  of  almost  unqualified  praise. 
The  work  is  not  of  a  controversial,  but  of  a  didactic 
character ;  and,  as  such,  we  hail  it,  and  recommend 
it  for  a  text-book,  guide,  and  constant  companion  to 
every  practitioner  and  every  student  who  wishes  to 
extricate  himself  from  the  well-worn  ruts  of  empiri- 
cism, and  to  base  his  practice  of  medicine  upon  prin- 
ciples — London  Lancet,  Dec.  27, 1856. 

A  text-book  to  which  no  other  in  oxxT  language  is 
comparable. — Charleston  Me.dical  Journal. 

No  work  has  ever  achieved  or  maintained  a  more 
deserved  reputation. — Virginia  Med.  and  Surg.  Journ. 

The  Principles  of  Medicine  of  Dr.  Williams  has,  by 
common  consent,  become  one  of  the  classics  of  our 
profession.  Few  works  have  done  more  towards  ac- 
complishing that  union  of  the  science  and  practice  of 
medicine  so  indispensable  for  its  perfection,  and  which 
are  too  apt,to  be  found  separate  from  each  other — a 
separation,  the  inevitable  tendency  of  which  must  ever 
be  to  favor  empiricism.  The  rapid  sale  of  three  edi- 
tions of  this  work  in  our  country  we  regard  as  a 
marked  tribute  to  its  value,  and  as  no  less  compli- 
mentary to  the  discrimination  and  appreciation  of  the 
profession  here  in  giving  rise  to  such  a  demand. — jV. 
Y.  Medical  Times. 

The  work  as  now  presented  to  the  public,  is  perhaps 
the  most  perfect  of  any  other  treating  on  similar  sub- 
jects; it  combines  the  science  and  the  art,  the  theory 


and  the  practice,  in  a  most  masterly  manner,  and  we 
feel  confident  that  as  knowledge  of  the  practical  views 
and  scientific  principles  laid  down  in  the  book  become 
generally  known,  medicine — practical  medicine— will 
advance,  in  the  same  proportion,  to  a  greater  perfec- 
tion and  certainty. — N.  Orleans  Med.  and  Su7-g.  Journ. 

There  is  no  work  in  medical  literature  which  can  fill 
the  place  of  this  one.  It  is  the  Primer  of  the  young 
practitioner,  the  Koran  of  the  scientific  one.  Three 
large  editions  of  it  have  already  been  exhausted  in  the 
United  States,  and  now  the  fourth  is  presented.  It 
must  have,  so  long  as  the  size  of  the  volume  remains 
uncumbersome,  the  first  place  among  pathological  au- 
thorities. We  feel  warranted  in  saying  that  no  medi- 
cal book  has  yet  been  written  which  contains  so  much 
in  the  small  number  of  pages  which  compose  this  one, 
and  yet  it  is  complete.  It  takes  up  disease  at  its  very 
foundation,  and  treats  of  its  fundamental  nature  in  a 
logical  and  inductive  style. — The  Stethoscope. 

This  exceedingly  valuable  work  is  the  best,  we  be- 
lieve, in  the  whole  round  of  medical  literature.  The 
division  of  the  different  subjects  is  excellent.  The  au- 
thor's method  of  investigation  and  mode  of  expression, 
in  our  judgment,  are  faultless.  We  can  most  cheer- 
fully commend  the  work  as  the  best  that  has  ever 
appeared  on  the  principles  of  medicine,  and  we  would 
advise  young  practitioners  especially  to  furnish  them- 
selves with  a  copy,  as  well  for  the  value  of  the  informa- 
tion it  contains  as  for  the  facilities  it  will  afford  them 
in  the  prosecutionof  their  own  investigations. — Soutli- 
ern  Journal  of  the  Med.  and  Phys  Sciences. 

The  best  exposition  in  our  language,  or,  we  believe, 
in  any  language,  of  rational  medicine,  in  its  present 
improved  and  rapidly  improving  state. — British  and 
Foreign  Medico-Chirurgical  Review. 


WHAT  TO   OBSERVE 

AT  THE  BEDSIDE  AND  AFTER  DEATH,  IN  MEDICAL  CASES.  Published  under  the 
authority  of  the  London  Society  for  Medical  Observation.  A  new  American  from  the  Se- 
cond and  Revised  London  edition.     In  one  very  handsome  volume,  royal  12mo  ,  extra  cloth, 


A  MANUAL  OF  CLINICAL  MEDICINE  AND  PHYSICAL  DIAGNOSIS.  By 
Thomas  H.  Tanner,  M.  D.,  Physician  to  the  Hospital  for  Women,  &c.  Second  American 
edition.  In  one  neat  volume,  small  12mo.,  extra  cloth,  88  cts. ;  or  in  flexible  cloth  for  the 
pocket,  80  cts. 


DUNGLISON'S    PRACTICE. 

THE  PRACTICE  OF  MEDICINE:  A  Treatise  on  Special  Pathology  and  Thera- 
peutics. By  RoBLEY  DuNGLisoN,  M.  D.,  Professor  of  the  Institutes  of  Medicine  in  Jefferson 
Medical  College,  Philadelphia.  Third  and  revised  edition.  In  two  large  octavo  volumes  of 
about  fifteen  hundred  pages;  leather,  f6  25. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


37 


New  and  much  enlarged  edition  of  "WATSON'S  PKACTICE"— Just  Ready  (185S). 

LECTURES  ON  THE 

PRKfCIPLES  AND  PRACTICE  OF  PHYSIC. 

DELIVERED    AT    KING'S    COLLEGE,    LONDON. 
BY   THOMAS   WATSON,  M.  D., 

Late  Physician  to  the  Middlesex  Hospital,  &c. 

^  mbs  ^nt^ritait,  from  t^e  last  llebiseb  nnb  inlargcb  ^itgltsl^  ©iritioit. 
With  Additions,  by  D.  FRANCIS  CONDIE,  M.D., 

Author  of  "A  Practical  Treatise  on  the  Diseases  of  Children,"  &c. 

WITH   ONE   HUNDRED   AND   EIGHTY-FIVE  ILLUSTRATIONS   ON   WOOD. 

Bi  one  very  large  and  handsome  vohtme,  imperial  octavo^  of  over  1200  large  and  closely  printed 
pages,  in  sm,all  type;  the  whole  strongly  botind  in  leather,  with  raised  bands.    Price  $4  25. 


The  publishers  feel  that  they  are  rendering  a  service  to 
the  American  profession  in  presenting  at  so  very  mode- 
rate a  price  this  vast  body  of  sound  practical  information. 
Whether  as  a  guide  for  the  student  entering  on  a  course 
of  instruction,  or  as  a  book  of  reference  for  daily  con- 
sultation by  the  practitioner,  "Watson's  Practice"  has 
long  been  regarded  as  second  to  none;  the  soundness  and 
fulness  of  its  teachings,  the  breadth  and  liberality  of  its 
views,  and  the  easy  and  flowing  style  in  which  it  is  writ- 
ten having  won  for  it  the  position  of  a  general  favorite. 
That  this  high  reputation  might  be  fully  maintained,  the 
author  has  subjected  it  to  a  thorough  revision ;  every 
portion  has  been  examined  with  the  aid  of  the  most  re- 
cent researches  in  pathology,  and  the  results  of  modern 
investigations  in  both  theoretical  and  practical  subjects 
have  been  carefully  weighed  and  embodied  throughout  its 
pages.  The  watchful  scrutiny  of  the  editor  has  likewise 
introduced  whatever  possesses  immediate  importance  to 
the  American  physician  in  relation  to  diseases  incident  to 
our  climate  which  are  little  known  in  England,  as  well  as 
those  points  in  which  experience  here  has  led  to  different 
modes  of  practice ;  and  he  has  also  added  largely  to  the 
series  of  illustrations,  believing  that  in  this  manner  valu- 
able assistance  may  be  conveyed  to  the  student  in  eluci- 
dating the  text.  The  work  will,  therefore,  be  found 
thoroughly  on  a  level  with  the  most  advanced  state  of 
medical  science  on  both  sides  of  the  Atlantic. 

The  additions  which  the  work  has  received  are  shown 
by  the  fact  that  notwithstanding  an  enlargement  in  the 
size  of  the  page,  more  than  two  hundred  additional  pages 
have  been  necessary  to  accommodate  the  two  large  vo- 
lumes of  the  London  edition  (which  sells  at  ten  dollars) 
within  the  compass  of  a  single  volume,  and  in  its  present 
form  it  contains  the  matter  of  at  least  three  ordinary  oc- 
tavos. Believing  it  to  be  a  work  which  should  lie  on  the 
table  of  every  physician,  and  be  in  the  hands  ot  every 
student,  the  publishers  have  put  it  at  a  price  within  the 
reach  of  all,  making  it  one  of  the  cheapest  books  as  yet 
presented  to  the  American  profession,  while  at  the  same 
time  the  beauty  of  its  mechanical  execution  renders  it  an 
exceedingly  attractive  volume. 


Stomach  contracted  from  chronic 
ulctraaon. 


38 


BLANCHARD    AND    LEA'S 


New  and  Improved  Edition — Now  Ready  (June,  1859). 

ELEMENTS  OE  MEDICINE: 
A  COMPENDIOUS  VIEW  OF  PATHOLOGY  AND  THERAPEUTICS; 

OR,  THE  HISTORY  AND  TREATMENT  OF  DISEASES. 
BY  SAMUEL  H.  DICKSON,  M.  D., 

Professor  of  the  Practice  of  Medicine  in  the  Jefferson  Medical  College  of  Philadelphia. 
In  one  large  and  handsome  octavo  volume  of  750  pages  ;  leather,  $3  75. 

The  steady  demand  which  has  so  soon  exhausted  the  first  edition  of  this  work,  sufficiently 
shows  that  the  author  was  not  mistaken  in  supposing  that  a  volume  of  this  character  was  need- 
ed— an  elementary  manual  of  practice,  which  should  present  the  leading  principles  of  medicine 
with  the  practical  results,  in  a  condensed  and  perspicuous  manner.  Disencumbered  of  unneces- 
sary detail  and  fruitless  speculations,  it  embodies  what  is  most  requisite  for  the  student  to  learn, 
and  at  the  same  time  what  the  active  practitioner  wants  when  obliged,  in  the  daily  calls  of  his 
profession,  to  refresh  his  memory  on  special  points.  The  clear  and  attractive  style  of  the  au- 
thor renders  the  whole  easy  of  comprehension,  while  his  long  experience  gives  to  his  teachings 
an  authority  everywhere  acknowledged.  Few  physicians,  indeed,  have  had  wider  opportunities 
for  observation  and  experience,  and  few,  perhaps,  have  used  them  to  better  purpose.  As  the 
result  of  a  long  life  devoted  to  study  and  practice,  the  present  edition,  revised  and  brought  up 
to  the  date  of  publication,  will  doubtless  maintain  the  reputation  already  acquired  as  a  condensed 
and  convenient  American  text-book  on  the  Practice  of  Medicine. 

A  few  notices  of  the  first  edition  are  appended. 


This  book  is  eminently  what  it  professes  to  be;  a  dis- 
tinguished merit  in  these  days.  Desisned  for  "  Teachers 
and  Students  of  Medicine,"  and  admirably  suited  to 
their  wants,  we  think  it  will  be  received,  on  its  own 
merits,  with  a  hearty  welcome. — Boston  Med.  and  Surg. 
Journal. 

The  volume  is  admirably  adapted  to  supply  a  want 
long  since  felt  by  the  American  student  and  young 
practitioner  of  medicine,  with  reference  to  whom  it  has 
evidently  been  prepared.  This  class  will  find  it  a  ju- 
dicious and  valuable  compend  of  the  elements  of 
medicine. — N.  T.  Journal  of  Medicine,  Sept.  1856. 

Indited  by  one  of  the  most  accomplished  writers  of 
our  country,  as  well  as  by  one  who  has  long  held  a 
high  position  among  teachers  and  practitioners  of 
medicine,  this  work  is  entitled  to  patronage  and  care- 
ful study.  The  learned  author  has  endeavored  to  con- 
dense in  this  volume  most  of  the  practical  matter  con- 
tained in  his  former  productions,  so  as  to  adapt  it  to 
the  use  of  those  who  have  not  time  to  devote  to  more 
extensive  works. — Southern  Med.  and  Surg.  Journal. 

We  can  strongly  recommend  Dr.  Dickson's  work  to 
our  readers  as  one  of  interest  and  practical  utility, 
well  deserving  of  a  place  in  their  libraries  as  a  book 
of  reference;  and  we  especially  commend  the  first  part 
as  presenting  an  admirable  outline  of  the  principles 
of  medicine. — Dublin  Quarterly  Journal. 

This  volume  is  designed  as  a  text-book  for  teachers 
and  students;  but  its  merits  extend  far  beyond  its 
modest  dedication;  it  is  a  complete  treatise  upon  me- 


dicine, and  one  that  will  stand  the  test  of  years.  The 
arrangement  is  simple,  a  feature  oftentimes  obscured 
in  otherwise  excellent  works.  This  Treatise  is  a  valu- 
able addition  to  our  medical  literature,  and  in  the  clear 
and  accurate  descriptions,  purity,  and  simplicity  of 
style,  and  soundness  of  precept,  the  reader  will  find 
much  to  admire  and  adopt,  and  not  a  little  that  calls 
for  deep  reflection.  We  cordially  recommend  this 
volume  to  our  readers,  whether  old  practitioners  or 
students,  for  we  take  it  that  the  physician  should  al- 
ways be  a  student. — American  Lancet. 

Prof  Dickson's  work  supplies,  to  a  great  extent,  a 
desideratum  long  felt  in  American  medicine. — iV.  O. 

Med.  and  Surg.  Journal. 

Estimating  this  work  according  to  the  purpose  for 
which  it  is  designed,  we  must  think  highly  of  its  me- 
rits, and  we  have  no  hesitation  in  predicting  for  it  a 
favorable  reception  by  both  students  and  teachers. 

Not  professing  to  be  a  complete  and  comprehensive 
treatise,  it  will  not  be  found  full  in  detail,  nor  filled 
with  discussions  of  theories  and  opinions,  but  em- 
bracing all  that  is  essential  in  theory  and  practice,  it 
is  admirably  adapted  to  the  wants  of  the  American 
student.  Avoiding  all  that  is  uncertain,  it  presents 
more  clearly  to  the  mind  of  the  reader  that  which  i.s 
established  and  verified  by  experience.  The  varied 
and  extensive  reading  of  the  author  is  conspicuously 
apparent,  and  all  the  recent  improvements  and  dis- 
coveries in  therapeutics  and  pathology  are  chronicled 
in  its  pages. — Charleston  Med.  Journal. 


A  New  Text-Book  on  Practice— (Lately  Issued.) 


A  MANUAL  OE  THE  PRACTICE  OE  MEDICINE. 

BY  GEORGE  H.  BARLOW,  M.  D., 

Physician  to  Guy's  Hospital,  London,  &c. 

With  Additions  by  D.  E.  CONDIE,  M.D., 

Author  of  "A  Practical  Treatise  on  the  Diseases  of  Children,"  &c. 
I7i  one  handsome  octavo  volume  of  over  six  Mmdred  pages;  leather,  $2  75. 


We  recommend  Dr.  Barlow's  Manual  in  the  warm- 
est manner  as  a  most  valuable  vade-mecum.  We  have 
had  frequent  occasion  to  consult  it,  and  have  found  it 
clear,  concise,  practical,  and  sound.  It  is  eminently 
a  practical  work,  containing  all  that  is  essential,  and 
avoiding  useless  theoretical  discussion.  The  work 
supplies  what  has  been  for  some  time  wanting,  a 
manual  of  practice  based  upon  modern  discoveries  in 
pathology  and  rational  views  of  treatment  of  disease 
It  is  especiiilly  intended  for  the  use  of  students  and 
junior  practitioners,  but  it  will  be  found  hardly  less 


useful  to  the  experienced  physician.  The  American 
editor  has  added  to  the  work  three  chapters— on 
Cholera  Infantum,  Yellow  Fever,  and  Cerebro-spinal 
Meningitis.  These  additions,  the  two  first  of  which 
are  indispensable  to  a  work  on  practice  destined  for 
the  profession  in  this  countr}',  are  executed  with  great 
judgment  and  fidelity,  by  Dr.  Condie,  who  has  also 
succeeded  happily  in  imitating  the  conciseness  and 
clearness  of  style  which  are  such  agreeable  character- 
istics of  the  originial  'hook.— Boston  Med.  and  Surg. 
Journal. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


39 


LA  ROCHE  ON  YELLOW  FEVER— (Just  Issued. 


YELLOW  FEYER, 

CONSIDERED  IN 

ITS  HISTORICAL,  PATHOLOGICAL,  ETIOLOGICAL,  AND  THERAPEUTICAL  RELATIONS: 

INCLUDING 

A  Sketch,  of  the  Disease  as  it  has  occurred  in  Philadelphia  from  1699  to  1854. 

With  an  Bzamination  of  the  Connedions  between  it  and  the  Fevers  known  under  the  same  name 
in  other  parts  of  Temperate  as  well  as  in  Tropical  Regions, 

BY  R.  LA  ROCHE,  M.  D. 

In  two  large  and  handsome  octavo  volumes  of  nearly  1500  pages  ;  extra  cloth,  $7. 

The  publishers  are  happy  in  being  able  at  length  to  present  to  ihe  profession  this  great  work, 
which  they  are  assured  will  be  regarded  as  an  honor  to  the  medical  literature  of  the  country. 
As  the  result  of  many  years  of  personal  observation  and  study,  as  embodying  an  intelligent  re- 
sume of  all  that  has  been  written  regarding  the  disease,  and  as  exhausting  the  subject  in  all  its 
various  aspects,  these  volumes  must  at  once  talce  the  position  of  the  standard  authority  and  work 
of  reference  on  the  many  important  questions  brought  into  consideration. 


From  Professor  S.  H.  Diclcson,  Ckarlestmi,  S.  C. 
A  monument  of  intelligent  and  well-applied  re- 
search, almost  without  example.  It  is,  indeed,  in  it- 
self, a  large  lilirary,  and  is  destined  to  constitute  the 
special  resort  as  a  book  of  reference,  on  the  subject  of 
which  it  treats,  to  all  future  time. 

We  have  not  time  at  present,  engaged  as  we  are,  by 
day  and  by  night,  in  the  work  of  combating  this  very 
disease,  now  prevailing  in  our  city,  to  do  more  than 
give  this  cursory  notice  of  what  we  consider  as  un- 
doubtedly the  most  able  and  erudite  medical  publica- 
tion our  country  has  yet  produced.  But  in  view  of 
the  startling  fact,  that  this,  the  most  malignant  and 
unmanageable  disease  of  modern  times,  has  for  several 
years  been  prevailing  in  our  country  to  a  greater  ex- 
tent than  ever  before;  that  it  is  no  longer  confined  to 
either  large  or  small  cities,  but  penetrates  country 
villages,  plantations,  and  farm-houses;  that  it  is  treated 
with  scarcely  better  success  now  than  thirty  or  forty 
years  ago ;  that  there  is  vast  mischief  done  by  ignorant 
pretenders  to  knowledge  in  regard  to  the  disease,  and 
in  view  of  the  probability  that  a  majority  of  southern 
physicians  will  be  called  upon  to  treat  the  disease,  we 
trust  that  this  able  and  comprehensive  treatise  will 
be  very  generally  read  in  the  south. — Memphis  Med. 
Recorder. 

This  is  decidedly  the  great  American  medical  work 
of  the  day — a  full,  complete,  and  systematic  treatise, 
unequalled  by  any  other  upon  the  all-important  sub- 
ject of  Yellow  Fever.  The  laborious,  indefatigable, 
and  learned  author  has  devoted  to  it  many  years  of 
arduous  research  and  careful  study,  and  the  result  is 
such  as  will  reflect  the  highest  honor  upon  the  author 
and  our  country. — Southern  Med.  and  Surg.  Journal. 

The  genius  and  scholarship  of  this  great  physician 
could  not  have  been  better  employed  than  in  the  erec- 
tion of  this  towering  monument  to  his  own  fame,  and 
to  the  glory  of  the  medical  literature  of  his  own  coun- 
try. It  is  destined  to  remain  the  great  authority  upon 
the  subject  of  Yellow  Fever.  The  student  and  phy- 
sician will  find  in  these  volumes  a  risumi  of  the  sum 
total  of  the  knowledge  of  the  world  upon  the  awful 
scourge  which  they  so  elaborately  discuss.  The  style 
is  so  soft  and  so  pure  as  to  refresh  and  invigorate  the 
mind  while  absorbing  the  thoughts  of  the  gifted  author, 


while  the  publishers  have  succeeded  in  bringing  the 
externals  into  a  most  felicitous  harmony  with  the 
inspiration  that  dwells  within.  Take  it  all  in  all,  it 
is  a  book  we  have  often  dreamed  of,  but  dreamed  not 
that  it  would  ever  meet  our  waking  eye  as  a  tangible 
reality. — Nashville  Journal  nf  Medicine. 

We  deem  it  fortunate  that  the  splendid  work  of  Dr. 
La  Roche  should  have  been  issued  from  the  press  at 
this  particular  time.  The  want  of  a  reliable  digest  of 
all  that  is  known  in  relation  to  this  frightful  malady 
has  long  been  felt — a  want  very  satisfactorily  met  in 
the  work  before  us.  We  deem  it  but  faint  praise  to 
say  that  Dr.  La  Roche  has  succeeded  in  presenting  the 
profession  with  an  able  and  complete  monograph,  one 
which  will  find  its  way  into  every  well  ordered  library. 
—  Va.  Stethoscope. 

Although  we  have  no  doubt  that  controversial  trea- 
tises on  the  mode  of  origin  and  propagation  of  the  fever 
in  question  will,  as  heretofore,  occasionally  appear, 
yet  it  must  be  some  time  before  another  systematic 
work  can  arise  in  the  face  of  so  admirable  and  care- 
fully executed  a  one  as  the  present.  It  is  a  mine  of 
information,  quite  an  encyclopedia  of  references,  and 
resume  of  knowledge  relative  to  what  has  been  re- 
corded upon  the  subject. — Loivlon  Lancet. 

A  miracle  of  industry  and  research,  constitviting  a 
complete  library  of  reference  on  the  disease  of  which 
it  treats. — Dublin  Quarterly  Journal. 

Dr.  La  Roche's  work  embodies  all  that  is  wanted. 
It  is  a  compendium  of  the  whole  vast  literature  of 
Yellow  Fever.  Thanks  to  his  labors,  the  medical 
scholar  who  desires  to  be  profoundly  conversant  with 
all  that  pertains  to  the  subject  need  not  go  beyond 
these  two  portly  volumes.  As  embodying  whatever 
is  important  in  all  that  has  been  hitherto  written  on 
the  subject,  it  will  be  a  work  for  reference  not  less 
valuable  in  ages  to  come  than  now.  Its  merit,  how- 
ever, by  no  means  consists  solely  in  its  completeness 
as  an  encyclopa^dian  work.  The  author  presents  the 
conclusions  to  which  he  is  led  by  a  philosophical  in- 
vestigation of  the  facts  and  opinions  gathered  from 
past  and  contemporaneous  publications.  Of  the  sound- 
ness of  the  conclusions  the  reader  can  judge  from  the 
data  which  are  spread  before  him. — Buffalo  Med.  Jour- 
nal, Sept.  1856. 


By  the  same  Author. 


PNEUMONIA;  its  Supposed  Connectiot],  Pathological  and  Etiological,  with 

Autumnal  Fevers,  including  an  Inquiry  into  the  Existence  and  Morbid  Agency  of  Malaria. 
In  one  handsome  octavo  volume,  extra  cloth,  of  500  pages.    $3. 


A  more  simple,  clear,  and  forcible  exposition  of  the 
groundless  nature  and  dangerous  tendency  of  certain 
pathological  and  etiological  heresies,  has  seldom  been 
presented  to  our  notice. — N.  Y.  Journal  of  Medicine 
and  Collateral  Science. 


This  work  should  be  carefully  studied  by  Southern 
physicians,  embodying  as  it  does  the  reflections  of  an 
original  thinker  and  close  observer  on  a  subject  pecu- 
liarly their  own. — Virginia  Medical  and  Surgical  Jour- 
nal. 


40 


BLANCHARD  AND  LEA'S 


New  and  Improved  Edition— Just  Issued. 
A. 9 


IN  ONE 

VERY  HANDSOME  OCTAVO  VOLUME, 

OF 

FIVE  HUNDRED  PAGES. 

■WITH 

Four  exquisite 

COLOEED    PLATES, 
AITD 

NUMEROUS    WOOD-CUTS. 
Extra  cloth,  S3  00. 


Suction  of  small  Portal  Vein  and  Canal. 


ON  DISEASES  OF  THE  LIVER. 

BY  GEORGE  BCDD,  M.D.,  F.  E.  S., 

Professor  of  Medicine  in  King's  College,  London,  &c. 

Spirit  g^merkEit,  from  t^£  Cljirb  anb  finlarg^b  l^onbon  6btlion, 


Has  fairly  established  for  itself  a  place  among  the 
classical  medical  literature  of  England. — Brilish  and 
Foreign  Medico-Chir.  Review,  July,  1857. 

Dr.  Budd's  Treatise  on  Diseases  of  the  Liver  is  now 
a  standard  work  in  Medical  literature,  and  during  the 
intervals  which  have  elapsed  between  the  successive 
editions,  the  author  has  incorporated  into  the  text  the 
most  striking  novelties  which  have  characterized  the 
recent  progress  of  hepatic  physiology  and  pathology ; 
80  that  although  the  size  of  the  book  is  not  percepti- 


bly changed,  the  history  of  liver  diseases  is  made  more 
complete,  and  is  kept  upon  a  level  with  the  progress 
of  modern  science.  It  is  the  best  work  on  diseases  of 
the  liver  in  any  language. — London  Med.  Times  and 
Gazette.,  June  27,  1857. 

This  work,  now  the  standard  book  of  reference  on 
the  disea.ses  of  which  it  treats,  has  been  carefully  re- 
vised, and  many  new  illustrations  of  the  views  of  the 
learned  author  added  in  the  present  edition. — Dublin 
Quarterly  Journal,  Aug.  1857. 


By  the  same  Author— (Just  Issued.) 
ON   THE    ORGANIC   DISEASES    AND    FUNCTIONAL    DISORDERS   OF 

THE    STOIVI^CH. 

In  one  neat  octavo  voluTne,  of  two  hundred  and  fifty  pages,  extra  cloth,  $1  50. 


LALLEMAND  AND  WILSON  ON  SPERMATORRHCBA— (Now  Ready). 
A    PRACTICAL  TREATISE    ON   THE   CAUSES,   SYMPTOMS,  AND 

TREATMENT  OF  SPERMATORRHCBA.  By  M.  Lallemand.  Translated  and  edited 
by  Henry  J.  McDougall  Third  American  edition.  To  whicli  is  added— ON  DISEASES 
OF  THE  VESICUL.'E  SEMINALES,  and  their  associated  organs.  With  special  re- 
ference to  the  Morbid  Secretions  of  the  Prostatic  and  Urethral  Mucous  Membrane.  By  Mae- 
Ris  WiLSONj  M.  D.    Ill  one  neat  octavo  volume,  of  about  400  pp.,  extra  cloth.     $2. 


FEVERS,  THEIR  DIAGNOSIS,  PATHOLOGY,  AND 
TREATMENT.  Prepared  and  edited,  with  large 
Additions,  from  the  Essays  on  Fever  in  Tweedie's 
Library.  By  Meredith  Clymer,  M.  D.  In  one  octavo 
volume,  of  six  hundred  pages,  $1  50. 

HUGHES'  CLINICAL  INTRODUCTION  TO  THE 
PRACTICE  OF  AUSCULTATION  AND  OTHER 
MODES  OF  PHYSICAL  DIAGNOSIS,  IN  DIS- 
EASES OF  THE  LUNGS  AND  HEART.  Second 
American,  from  the  second  London  edition.  1  vol. 
royal  12mo.,  extra  cloth,  pp.  304.   $1. 


COPLAND  ON  PALSY.— Of  the  Causes,  Nature,  and 
Treatment  of  Palsy  and  Apoplexy.  In  one  volume, 
royal  12mo.,  80  cents. 

BLAKISTON'S  PRACTICAL  OBSERVATIONS  ON 
CERTAIN  DISEASES  OF  THE  CHEST,  and  on 
the  Principles  of  Auscultation.  In  one  vol.,  cloth, 
8vo.,  pp.  384.    $1  25. 

BUCKLER  ON  THE  ETIOLOGY,  PATHOLOGY, 
AND  TREATMENT  OF  FIBRO-BRONCHITIS  AND 
RHEUMATIC  PNEU.MONIA.  In  one  Svo.  vol.,  ex- 
tra cloth,  pp.  150.    $1  25. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS.  41 

FLINT  ON  RESPIRATORY  ORGANS— (Just  Issued.) 

PHYSICAL  EXPLORATION  AND  DIAGNOSIS 

OF  DISEASES  AEFECTING  THE  RESPIRATORY  ORGANS. 

BY  AUSTIN  FLINT,  M.  D., 

Professor  of  Clinical  Medicine  and  Pathologj'  in  the  University  of  Buffalo,  &c. 
I7i  one  large  and  handsome  octavo  volume  of  six  hundred  and  thirty-six  pages ;  extra  cloth,  $3. 


Dr.  Flint  is  one  of  the  most  industrious  and  ener- 
p;etio  men  in  the  medical  profession  of  this  country. 
His  previous  contributions  to  our  medical  literature 
have  won  for  him  both  American  and  European  repu- 
tation, and  we  assure  our  readers  that  the  present 
volume  is  full  of  valuable  and  interesting  matter. 
We  unhesitatingly  commend  the  book  to  all  who  wish 
to  become  well  acquainted  with  thoracic  diseases  and 
the  signs  by  which  they  may  be  distinguished. — N.  W. 
Med.  and  Surg.  Journal,  Nov.  1856. 

We  have  selected  these  points  in  the  physical  ex- 
ploration of  the  chest  not  only  from  their  importance, 
but  to  show  the  manner  in  which  Dr.  Flint  handles 
his  subject.  Our  readers  will,  we  doubt  not,  agree 
with  us  in  the  opinion  that  he  has  done  this  carefully, 
thoroughly,  and  judiciously. — Charleston  Med,  Jour- 
nal, Nov.  1856. 

We  can  only  state  our  general  impression  of  the 


A  work  of  original  observation  of  the  highest  merit. 
We  recommend  the  treatise  to  every  one  who  wishes 
to  become  a  correct  auscultator.  Based  to  a  very  large 
extent  upon  cases  numerically  examined,  it  carries 
the  evidences  of  careful  study  and  discrimination  upon 
every  page.  It  does  credit  to  the  author,  and.  through 
him,  to  the  profession  in  this  country.  It  is,  what  we 
cannot  call  every  book  upon  aiiscultation,  a  readable 
book. — Am.  Journal  Med.  Sciences. 

A  work,  of  which  we  cannot  but  admire  the  spirit 
that  has  presided  over  its  composition.  There  is  an 
evident  accuracy  aimed  at  throughout  by  means  of 
the  carefully  noted  cases,  and  a  searching  after  truth 
which  recommends  the  volume  highly  to  the  attention 
of  the  profession. — Med.  Examiner. 

This  is  the  most  elaborate  work  devoted  exclusively 
to  the  physical  exploration  of  diseases  of  the  lungs, 


high  value  of  this  work,  and  cordially  recommend  it  i  with  which  we  are  acquainted  in  the  English  lan- 
to  all.    We  regard  it,  in  point  both  of  arrangement  \  guage.    From  the  high  standing  of  the  author  as  a 


and  of  the  marked  ability  of  its  treatment  of  the  sub- 
jects, aS  destined  to  take  the  first  rank  in  works  of  this 
class.  So  far  as  our  information  extends,  it  has  at 
present  no  equal.  To  the  practitioner,  as  well  as  the 
student,  it  will  be  invaluable  in  clearing  up  the  diag- 
nosis of  doubtful  cases,  and  in  shedding  light  upon 
difficult  phenomena. — Buffalo  Med.  Journal. 


clinical  teacher,  and  his  known  devotion,  during  many 
years,  to  the  study  of  thoracic  diseases,  much  was  to 
be  expected  from  the  announcement  of  his  determin- 
ation to  embody  in  the  form  of  a  treatise,  the  results 
of  his  study  and  experience. — Boston  Med.  and  Surg. 
Journal. 


By  the  same  Author— (In  Press.^ 
THE  DIAGNOSIS,  PATHOLOGY,  AND  TREATMENT  OF 

DISEASES    OE    THE    HE^HT. 

In  one  neat  octavo  volume,  of  nearly  500  pages. 

This  work  is  now  so  far  advanced  that  the  publishers  can  promise  it  with  confidence  for  the 
autumn  of  1859.  The  reputation  of  the  author,  and  the  attention  which  he  lias  long  paid  to  this 
department  of  pracical  medicine,  are  sufficient  guarantee  that  the  present  volume  will  supply 
the  want  which  has  long  been  felt  of  a  complete  and  authoritative  treatise  on  the  subject. 

Just  Issued, 

MEDICAL  NOTES  AND  REFLECTIONS. 

BY  SIK  HENRY  HOLLAND,  Bart.,  F.  E.  S., 

Physician  in  Ordinary  to  the  Queen,  &c. 
FRON/1    -THE    THIRD    AND     ENt-ARGED     ENQI-ISH     EDITION. 

1)1  one  handsome  octavo  volume  of  about  five  hundred  pages,  extra  doth,  $3  GO. 
Just  Issued. 


CLINICAL  LECTURES  ON  CERTAIN  DISEASES  OF  THE 

URINARY  ORGANS,  AND   ON   DROPSIES, 

BY  ROBERT  BENTLEY  TODD,  M.  D.,  F.  R.  S., 

Physician  to  King's  College  Hospital,  &c. 
In  one  handsome  octavo  volume,  of  270  pages,  extra  cloth,  $1  50. 

By  the  same  Author — (In  Press.) 

CLINIC  AiTlECTURES 
ON  OEKTAIN  ACUTE  DISEASES. 

In  one  neat  octavo  volume,  extra  cloth. 


42 


BLANCHARD  &  LEA'S 


Publishing  in  the  "Medical  News  and  Library,"  1858  and  1859. 
PATHOLOGICAL  AND  PRACTICAL  OBSERVATIONS 

OX  DISEASES  OF  THE  ALIMENTARY  CAXAL,  (ESOPHAGUS,  STOMACH, 

CECUM,  AND  INTESTINES. 

By  S.  0.  HABERSHOX,  M.  D., 

Assistant  Physician  to  and  Lecturer  on  Materia  Medica  and  Tiieraiieutics  at  Guy's  Hospital. 

WITH    HANDSOME    ILLUSTRATIONS   ON    WOOD. 


|^°  B}^  reference  to 
the  Terms  of  the  "Ame- 
rican Journal  of  the 
Medical  Sciences," 
pp.  3  and  4,  it  will  be 
seen  that  advance-pay- 
ing subscribers  obtain 
this  valuable  practical 
work  without  charg'e. 


He  takes  us  well  through  all  the  diseases,  structural 
and  functional  (as  they  are  called),  of  the  alimentary 
canal.  He  begins  at  the  pharynx,  and  carefully  and 
honestly  follows  the  tube  through  all  its  constrictions, 
dilatations,  divarications,  and  appendices.  He  tells  us 
what  misfortunes  happen  at  every  part  of  it:  he  de- 
scribes the  particular  seat  of  the  disease  at  each  con- 
ventional division  of  the  apparatus;  their  anatomical 
characters  (when  they  have  any);  their  general  patho- 
logy: the  symptoms  they  excite;  the  conditions  of  the 
system  with  which  they  are  coincident;  the  particular 
general  disorder  with  which  they  are  associated :  and 
he  also  tells  us  what  aids  medicine  offers  man  to  help 
him  through  these  numerous  dangers  and  difficulties; 
and  how  those  aids  are  to  be  wisely  used  to  their  ends. 
The  practitioner  will  find  it  a  valuable  work  of  refer- 
ence.— London  Med.  Times  and  Gaz..  Nov.  7, 1857. 

Dr.  Habershon  abstains,  as  a  rule,  from  speculations, 
and  confines  himself  mainly  to  the  record  of  facts  re- 
lating to  symptoms,  morbid  chanses,  and  treatment. 
His  remarks  are  illustrated  by  the  histories  of  one  I 


THE 
PATHOLOGY  AND  TREATMENT 

OF 

PULMOMRT  TUBERCULOSIS, 

AND  ON 

THE  LOCAL  MEDICATION  OF  PHARYNGEAL  AND 
LARYNGEAL  DISEASES  FREQUENTLY  MIS- 
TAKEN FOR  OR  ASSOCIATED 
WITH  PHTHISIS. 


Chronic  Ulcer  of  Stomach. 

hundred  and  sixty-three  cases,  recorded  in  the  ease- 
books  of  Guy's  Hospital,  descriptive  of  the  numerous 
forms  of  disea.«e  of  the  alimentary  canal.  The  book 
is  therefore  essentially  practical;  and  on  this  ground, 
and  bearing  evidence  of  being  the  work  of  a  careful 
observer,  it  forms  an  addition  of  value  to  the  already 
existing  literature  of  Diseases  of  the  Alimentary  Canal. 
British  Med.  Journal,  Nov.  21,  1857. 

Amongst  the  valuable  treatises  we  have  pointed  out 
there  yet  existed  room  for  a  work  which  should  deal 
but  little  with  theory  and  scientific  analyses,  but  con- 
fine itself  to  the  record  of  direct  bedside  and  post- 
mortem, room  results.  Dr.  Habershon"s  treatise  sup- 
plies this  deficiency.  We  recommend  Dr.  Habershon's 
treatise  as  a  valuable  repertory  of  clinical  experience, 
of  very  trustworthy  character. — London  Lancet,  Nov. 
21,  1857. 

We  believe  that  this  book  will  be  read  with  interest. 
It  is  calculated  to  impart  instruction  to  all  of  us. — 
Brit,  and  For.  Medico-Chirurg .  Meview,  April,  1858. 


J.  HUGHES  BENNETT,  M.  D.,  F.R.S.E., 

Professor  of  Clinical  Medicine  in  the  ITniversily 
of  Edinburgh,  &e. 


Ill  one  small  octavo  volume,  extra  cloth,  with  beau- 
tiful illustrations.     $1  '25. 


Tubercular  Cavity  in  the  act  of  Healing. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


43 


RICORD  AND  HUNTER  ON  VENEREAL— New  Edition,  Now  Ready  (1869). 

A  TREATISE  01  THE"yENEREAL  DISEASE. 

BY  JOHN  HUNTER,  F.  K  S.,  &c. 

With  Copious  Additions  by  PH.  RICORD,  M.  D. 

Second  Edition,  containing  a  resume  of  Ricord's  recent  Lectures  on  Chancre. 

Translated  and  Edited,  witu  Notes,  by  FREEMAN  J.  BUMSTEAD,  M.D., 

Lecturer  on  Venereal  at  the  College  of  Physicians  and  Surgeons,  New  York. 

Ill  07ie  large  and  handsome  octavo  volume  of  550  pages,  with  eight  plates  ;  extra  cloth,  $3  25. 

"M.  Ricord's  annotations  to  Hunters  Treatise  on  the  Venereal  Disease  were  first  published 
at  Paris,  in  1840,  in  connection  with  Dr.  G.  Richelot's  translation  of  the  work,  including  '.he 
contributions  of  Sir  Everard  Home  and  Mr.  Babington.  In  a  second  edition,  which  has  recently 
appeared,  M.  Ricord  has  thoroughly  revised  his  part  of  the  work,  bringing  it  up  to  the  knowledge 
of  the  present  day,  and  so  materially  increasing  it  that  it  now  constitutes  full  one-third  of  the 
voltirae.  This  publication  has  been  received  with  great  favor  by  the  French,  both  because  it 
has  placed  within  their  reach  an  important  work  of  Hunter,  and  also  because  it  is  the  only  recent 
practical  work  which  M.  Ricord  has  published,  no  edition  of  his  Traite  des  Maladies  Veneri- 
ennes  having  appeared  for  the  last  fifteen  years." — Translator'' s  Preface. 

The  addition,  in  the  present  edition,  of  the  material  contained  in  the  "Lectures  on  Chancre," 
published  a  few  months  since  by  M.  Ricord,  renders  this  work  the  most  complete  embodiment 
of  the  views  of  the  great  French  syphilographer  that  has  'vet  been  given  to  the  profession,  while 
the  editor  has  further  endeavored  to  present  all  other  matter  of  interest  that  has  appeared  since 
the  publication  of  the  first  edition.  The  volume  may  therefore  be  regarded  as  a  complete  work 
of  reference  on  the  subject  in  which  the  practitioner  may  at  all  times  be  certain  of  finding  an 
elucidation  of  doubtful  questions  either  of  theory  or  practice. 


Every  one  will  recognize  the  attractiveness  and 
value  which  this  work  derives  from  thus  presenting 
the  opinions  of  these  two  masters  side  by  side.  But, 
it  must  be  admitted,  what  has  made  the  fortune  of 
the  book,  is  the  fact  that  it  contains  the  "  most  com- 
plete embodiment  of  the  veritable  doctrines  of  the 
Hopital  du  Midi,"  which  has  ever  been  made  public. 
The  doctrinal  ideas  of  M.  Ricord,  ideas  which,  if  not 
universally  adopted,  are  incontestably  dominant,  have 
heretofore  only  been  interpreted  by  more  or  less  skilful 


secretaries,  sometimes  accredited  and  sometimes  not. 
Tn  the  notes  to  Hunter,  the  master  substitutes  himself 
for  his  interpreters,  and  gives  his  original  thoughts  to 
the  world,  in  a  summary  form  it  is  true,  but  in  a  lucid 
and  perfectly  intelligible  manner.  In  conclusion,  we 
can  say  that  this  is  incontestably  the  best  treatise  on 
syphilis  with  which  we  are  acquainted,  and,  as  we  do 
not  often  employ  the  phrase,  we  may  be  excused  for 
expressing  the  hope  that  it  may  find  a  place  in  the 
library  of  every  physician. — Va.  Med.  and  Surg.  Journ. 


Also  — HUNTER'S  COMPLETE  WORKS. 

numerous  Illustrations;  leather,  $10  00. 


In  four  octavo  volumes,  with 


RICORD'S 

LETTERS  ON  SYPHILIS, 

Addressed  to  the  Chief  Editor  of  the  Union  Medicale.      With  an  Introduction  by  Amedee 
Latour.    Translated  by  W.  P.  Lattimore,  M.  D.    In  one  neat  octavo  volume,  extra  cloth,  $2. 

Lately  Published. 

THE  MODERN  TRE/VTMENFoF  SYPHILITIC  DISEASES, 

BOTH    PRIMARY   AND    SECONDARY. 

COMPRISING  THE 

Treatment  of  Constitutional  and  confirmed  Syphilis  by  a  safe  and  successful  Method. 

WITH  NUMEROUS  CASES,  FORMULA,  AND  CLINICAL  OBSERVATIONS. 
BY  LANGSTON  PARKER, 

Surgeon  to  the  Queen's  Hospital,  Birmingham. 

Erom  the  Third  and  entirely  rewritten  London  Edition. 

Ill  one  neat  octavo  vohime  of  over  3QQ  pages,  extra  cloth,  $1  75. 

The  third  edition  of  Mr.  Parker's  work  constitutes,  I  has  contrived  to  emhody  in  it  everything  of  import- 
we  must  say,  an  excellent  practical  treatise,  the  suh-  auce  respecting  syphilis  and  its  treatment. — Dublin 
ject  is  remarkably  well  arranged;  indeed,  the  author  |  Medical  Press. 


LECTURES  ON  THE  PRINCIPLES  AND  METHODS  OF  MEDICAL  OB- 
SERVATION AND  RESEARCH.  For  the  use  of  Advanced  Students  and  Junior  Practi- 
tioners. By  Thomas  Laycock,  M.  D.,  F.  R.  S.  E.,  Professor  of  Practical  and  Clinical  Medi- 
cine in  the  University  of  Edinburgh,  etc.    In  one  very  neat  royal  12mo.  vol.,  extra  cloth,  $1. 


44 


BLANCHARD  AND  LEA'S 


NEW  AND  MUCH  IMPROVED  EDITION— (Just  Issued.) 

THE  HISTORY,  DIAGNOSIS,  AND  TREATMENT  OP  THE 

FEYERS   OF  THE  UNITED   STATES. 

BY  ELISHA  BARTLETT,  M.  D., 

Late  Professor  of  Materia  Medica,  &c.,  in  the  College  of  Physicians  and  Surgeons,  New  York. 

J^ourtlj  ibttion,  ^Itbxscb 
BY  ALONZO  CLARK,  M.  D., 

Professor  of  Pathology  and  Practical  Medicine  in  the  College  of  Physicians  and  Surgeons,  New  York. 

In  one  large  and  handsome  octavo  volume,  of  over  six  hundred  pages  ;  extra  cloth,  $3  00. 

From  the  Editor'' s  Preface. 
"  The  question  maybe  fairly  raised  whether  any  book  in  our  profession  illustrates  more  clearly 
the  beauties  of  sound  reasoning,  and  the  advantages  of  vigorous  generalization  from  carefully 
selected  facts.  Certainly  no  author  ever  brought  to  his  labor  a  more  high-minded  purpose  of 
representing  the  truth,  in  its  simplicity  and  m  its  fulness,  w^hile  (ew  have  been  possessed  of 
higher  gifts  to  discern,  and  gracefully  to  exhibit  it.  Had  I  been  prepared  by  previous  reading 
for  the  duty  which  the  partiality  of  Dr.  Bartlett  assigned  to  me,  of  preparing  this  edition  for  the 
press,  the  labor  would  have  been  inconsiderable.  As  it  is,  I  have  read  extensively,  to  learn 
how  little  that  the  book  contains  can  be  advantageously  altered.  Considerable  matter  has 
been  added,  it  is  true,  because  new  facts  have  been  observed,  and  new  opinions  have  been  ex- 
pressed, which  both  add  to  our  knowledge,  and  suggest  new  topics  for  investigation.  This  1 
have  endeavored  to  select,  and  so  far  as  it  is  original  to  write,  with  the  same  re>pect  for  truth, 
and  desire  for  usefulness,  which  influenced  the  mind  of  my  endeared  friend,  the  accomplished 
author." 

Carefully  revised  by  Professor  Clark,  who  has  introduced  whatever  is  new  in  the  literature 
of  this  branch  of  medical  science  since  the  appearance  of  the  last  edition,  embodying  the  results 
of  the  observations  and  researches  of  Drake,  La  Roche,  Flint,  Barton,  Dickson,  Fenner, 
Peacocke,  and  others,  this  volume  will  be  found  fully  brought  up  to  the  present  day,  and  emi- 
nently worthy  a  continuance  of  the  confidence  of  the  profession. 


The  masterly  and  elegant  treatise  by  Dr.  Bartlett  is 
invaluable  to  the  American  student  and  practitioner. 
— Dr.  Holmes's  Report  to  the  Nat.  Med.  Association. 

We  regard  it,  from  the  examination  we  have  made 
of  it,  the  best  work  on  fevers  extant  in  our  language, 
and  as  such  cordially  recommend  it  to  the  medical 
public. — St.  Louis  Medical  and  Surgical  Journal. 

Take  it  altogether,  it  is  the  most  complete  history  of 
our  fevers  which  has  yet  been  published,  and  every 
practitioner  should  avail  himself  of  its  contents. — The 
Western  Lancet. 


Of  the  value  and  importance  of  such  a  work,  it  is 
needless  here  to  speak;  the  profession  of  the  United 
States  owe  much  to  the  author  for  the  very  able 
volume  which  he  has  presented  to  them,  and  for  the 
careful  and  judicious  manner  in  which  he  has  executed 
his  task.  No  one  volume  with  which  we  are  acquainted 
contains  so  complete  a  history  of  our  fevers  as  this. 
To  Dr.  Bartlett  we  owe  our  best  thanks  for  the  very 
able  volume  he  has  given  us,  as  embodying  certainly 
the  most  complete,  methodical,  and  satisfactory  ac- 
count of  our  fevers  anywhere  to  be  met  with. — The 
Charleston  Med.  Journal  and  Review. 


THE    HTJ]M:A.N    BHA-IN; 

WITH  A 

DESCRIPTION  OF  THE  TYPICAL  FORMS  OF  BRAIN  IN  THE  ANIMAL  KINGDOM. 

BY  SAMUEL  SOLLY,  F.  R.  S., 

Senior  Assistant  Surgeon  to  St.  Thomas's 
Hospital,  &c. 

jFrom  i\t  snav.'ii  I/onlion  jcIJittDit. 

WITH 

ONE  HUNDRED  AND  EIGHTEEN 

ELABORATE    ILLUSTRATIONS 

ON   WOOD. 

In  one  handsome  octavo  volume,  of 

about  five  hundred  pages, 

extra  cloth,  %2  00. 

Inferior  Surfaceofthe  Cerebellum. 


MEDICAL   AND   SCIENTIFIC   PUBLICATIONS. 


45 


Just  Issued. 

ATLAS  or  CUTANEOUS  DISEASES. 

BY  J.  MOORE  NELIGAN,  M.  D.,  M.  R.  I.  A.,  &c. 

Willi  Splendid  Colored  Plates,  presenting  nearly  one  hundred  elaborate  representations 
of  Disease,  colored  after  nature. 

Ill  one  very  handsome  quarto  volume.,  extra  doth.,  price  $4  50. 
Also  now  ready,  by  the  same  Author. 

A  PRACTICAL  TREATISE  ON  DISEASES  OF  THE  SKIN. 

SECOND  AMERICAN  EDITION. 

In  one  neat  royal  12mo.  volume,  extra  cloth,  of  334 pages,  price  $1. 
These  two  volumes,  constituting-  together  a  complete  work  on  the  diagnos^is.  pathology,  and 
treatment  of  cutaneous  affections,  will  be  forwarded  by  mail  on  receipt  of  $5. 


A  compend  which  will  very  much  aid  the  practi- 
tioner in  this  difficult  branch  of  diagnosis.  Taken 
with  the  beautiful  plates  of  the  Atlas,  which  are  re- 
markable for  their  accuracy  and  beauty  of  coloring, 
it  constitutes  a  very  valuable  addition  to  the  library 
of  a  practical  man. — Buffalo  Med.  Journal. 

The  lithographs  are  so  colored  as  to  be  true  and 
faithful  representations  of  these  ninety  varieties  of  a 
class  of  diseases  whose  exact  diagnosis  is  thus  made 
plain  and  easy,  and  which,  in  the  absence  of  such  aid 
or  a  long  and  attentive  study,  is  so  difficult  that  very 
few  praotitioners  seriously  attempt  it.  The  work  is 
cheap,  and  no  practitioner  ambitious  of  a  high  profes- 
sional status  can  afford  to  dispense  with  such  helps. — 
JVashviUe  Journal  of  Medicine. 

Neligan's  Atlas  of  Cutaneous  Diseases  supplies  a  long 


existent  desideratum  much  felt  by  the  largest  class 
of  our  profession.  It  presents,  in  quarto  size,  16 
plates,  each  containing  from  3  to  6  figures,  and  form- 
ing in  all  a  total  of  90  distinct  representations  of  the 
different  species  of  skin  affections,  grouped  together  in 
genera  or  families.  The  illustrations  have  been  taken 
from  nature,  and  have  been  copied  with  such  fidelity 
that  they  present  a  striking  picture  of  life;  in  which 
the  reduced  scale  aptly  serves  to  give,  at  a  coup  d'ceil, 
the  remarkablepeculiaritiesofeach  individual  variety. 
And  while  thus  the  disease  is  rendered  more  definable, 
there  is  yet  no  loss  of  proportion  incurred  by  the  ne- 
cessary concentration.  Each  figure  is  highly  colored, 
and  so  truthful  has  the  artist  been  that  the  most  fas- 
tidious observer  could  not  justly  take  exception  to  the 
correctness  of  the  execution  of  the  pictures  under  his 
scrutiny. — Montreal  Med.  Chronicle. 


Ne-w  and  enlarged  Edition — No^w  Ready  (June,  1859). 

UEINARYT3EP0SITS; 

THEIR  DIAGNOSIS,  PATHOLOGY,  AND  THERAPEUTICAL  INDICATIONS. 

BY  GOLDING  BIRD,  M.  D.,  F.  R.  S.,  &c. 

Edited  bt  EDMUND  LLOYD  BIRKETT,  M.  D.,  &c. 

A  New  American,  from  the  Fifth  London  Edition. 
WITH  EIGHTY  ILLUSTRATIONS. 
In  one  handsoTne  octavo  volume,  extra  cloth,  of  382  pages,  $2  00. 
The  death  of  Dr.  Bird  has  rendered  it  necessary  to  entrust  the  revision  of  (he  present  edition 
to  other  hands,  and  in  his  performance  of  the  duty  thus  devolving  on  him,  Dr.  Birkett  has  sedu- 
lou^ly  endeavored  to  carry  out  the  author's  plan  by  introducing  such  new  matter  and  modifica- 
tions of  the  text  as  the  progress  of  science  has 
called  for.    Notwithstanding  the  utmost  care 
to  keep  the  work  within  a  reasonable  compass, 
these  additions  have  resulted  in  a  considerable 
enlargement.    It  is,  therefore,  hoped  that  it  will 
be  found  fulJy  up  to  the  present  condition  of  the 
subject,  and  that  the  reputation  of  the  volume 
as  a  clear,  complete,  and  compendious  manual, 
will  be  fully  maintained. 

It  can  scarcely  be  necessary  for  us  to  say  anything 
of  the  merits  of  this  well-known  Treatise,  which  so  ad- 
mirably brings  into  practical  application  the  results 
of  those  microscopical  and  chemical  researches  regard- 
ing the  physiology  and  pathology  of  the  urinary  se- 
cretion, which  have  contributed  so  much  to  the 
increase  of  our  diagnostic  powers,  and  to  the  extension 
and  satisfactory  employment  of  our  therapeutic  re- 
sources. In  the  preparation  of  this  new  edition  of  his 
work,  it  is  obvious  that  Dr.  Golding  Bird  has  spared 
no  pains  to  render  it  a  faithful  representation  of  the 
present  state  of  scientific  knowledge  on  the  subject  it 
embraces. — British  and  Foreign  Med.-Chir.  Review. 
Crystals  of  Phosphate  of  Soda. 


MANUALS  ON  THE  BLOOD  AND  URINE.— By  John  |  FRICK  ON    THE  URINE.— Renal  Affections,  their 
William  Griffith,  M.  D,,  G.  Owen  Reese,  M.  D.,  and  |      Diagnosis  and  Pathology.  In  one  handsome  volume, 
Alfred  Markwick.  In  one  large  12mo.  volume,  extra  I      royal  12mo.,  with  illustrations,  75  cents, 
cloth,  of  460  pages,  with  Plates,  $1  25.  I 


46 


BLANCHARD  AND  LEA'S 


The  Standard  work  on  the  Skin— (Just  Issued.) 

ON  i:>isea-Se:s~of  the  skidst. 

BY  ERASMUS  WILSON,  F.  R.  S., 

Author  of  "A  System  of  Human  Anatomy,"  &c. 

S;ije  Joitrtlj  anb  ^nlargeb  '^mmcmx,  from  tljc  last  anb  |mpra&cb  ITonbon  (Bbition. 

In,  one  large  octavo  vohime,  of  650  pages,  extra  cloth,  $2  75. 

This  volume,  in  passing  for  tlie  fourth  time  through  the  hands  of  the  author,  has  received  a 
careful  revision,  and  has  been  greatly  enlarged  and  improved.  About  one  hundred  and  fifty 
pages  have  been  added,  including  new  chapters  on  Classification,  on  General  Pathology,  on 
General  Therapeutics,  on  Furuncular  Eruptions,  and  on  Diseases  of  the  Nails,  besides  extensive 
•additions  throughout  the  text,  wherever  they  have  seemed  desirable,  either  from  former  omis- 
sions or  from  the  progress  of  science  and  the  increased  experience  of  the  author.  Appended  to 
the  volume  will  also  now  be  found  a  collection  of  Selected  FoemuLjE,  consisting  for  the  most 
part  of  prescriptions  of  which  the  author  has  tested  the  value. 

Thus  perfected  and  brought  up  to  the  latest  moment,  this  work  cannot  fail  to  maintain  its 
character  as  the  standard  authority  on  this  important  and  perplexing  class  of  affections. 


When  the  first  edition  of  this  work  appeared,  about 
fourteen  years  ago,  Mr.  Erasmus  Wilson  had  already 
given  some  years  to  the  study  of  Diseases  of  the  Skin, 
and  he  then  expressed  his  intention  of  devoting  his 
future  life  to  the  elucidation  of  this  particular  branch 
of  Medical  Science.  In  the  present  edition  Mr.  Wil- 
son presents  us  with  the  results  of  his  matured  ex- 
perience gained  after  an  extensive  acquaintance  with 
the  pathology  and  treatment  of  cutaneous  affections  ; 
and  we  have  now  before  us  not  merely  a  reprint  of 
his  former  publications,  but  an  entirely  new  and  re- 
written volume.  Thus,  the  whole  history  of  the  dis- 
eases affecting  the  skin,  whether  they  originate  in 


that  structure  or  are  the  mere  manifestations  of  de- 
rangement of  internal  organs,  is  brought  under  notice, 
and  the  book  includes  a  mass  of  information  which 
is  spread  over  a  great  part  of  the  domain  of  Medical 
and  Surgical  Pathology  We  can  safely  recommend 
it  to  the  profession  as  the  best  work  on  the  subject  now 
in  existence  in  the  English  language. — London  Med. 
Times  and  Gazette,  March  28, 1857. 

The  "  Diseases  of  the  Skin,"  by  Mr.  Erasmus  Wilson, 
may  now  be  regarded  as  the  standard  work  in  tliat 
department  of  medical  literature. — Medico-Chirurg . 
Review. 


Also,  Now  Ready. 

A  SERIES  OF  PLATES  IllUSTRATING  "WILSON  ON  DISEASES  OF  THE  SKIN." 

CONSISTING  OF  NINETEEN  BEAUTIFULLY  EXECUTED  PLATES,  OF  WHICH  TWELVE  AEE  EXQUISITELY  COLORED. 

Presenting  the  Normal  Anatomy  and  Pathology  of  the  S/dn,  and  embracing  accurate  repre- 
sentations of  about  one  hundred  varieties  of  Disease,  m,ost  of  them,  the  size  of 
Nature.    Price,  in  extra  cloth,  $4  25. 

For  beauty  of  drawing,  and  accuracy  and  finish  of  colorinff,  these  plates  are  confidently  pre- 
sented as  superior  to  anything  of  the  kind  as  yet  issued  in  this  country. 

The  plates  by  which  this  edition  is  accompanied 
leave  nothing  to  be  desired,  so  far  as  excellence  of 
delineation  and  perfect  accuracy  of  illustration  are 
concerned. — Medicc-Chirurgical  Review. 

Of  these  plates  it  is  impossible  to  speak  too  highly. 


The  representations  of  the  various  forms  of  cutaneous 
disease  are  singularly  accurate,  and  the  coloring  ex- 
ceeds almost  anything  we  have  met  with  in  point  of 
delicacy  and  finish." — British  and  Foreign  Medical 
Review. 


Epidermal  horn,  caused  by  Disease 
of  the  Oil  Glands. 


By  the  same  Author— (Lately  Issued.) 

HEALTHY  SKIN: 

A  Popular  Treatise  on  the  Skin  and  Hair,  their 
Preservation  and  Management. 

SECOND    AMERICAN,    PROM    THE    POUKTH    AND 
REVISED  LONDON  EDITION. 

J>i  o?ie  neat  royal  12mo.  volum,e,  of  about  three  htm- 

dred  pages,  with  numerous  Illustrations ; 

extra  cloth,  or  flexible  cloth,  $1  00  ; 

paper  covers,  75  ce7it . 

The  student  will  be  delighted  to  find  his  labors  so  much 
facilitated;  and  a  few  hours  of  agreeable  society  with  a  moat 
pleasantly-written  book  will  do  more  to  make  him  acquainted 
with  a  class  of  obscure  diseases  than  all  that  has  been  pre- 
viously written  on  the  subject. — London  Lancet. 


By  the  same  Author. 
ON   CONSTITUTIONAL   AND   HEREDITARY  SYPHILIS,   AND  ON 

SYPHILITIC  EHUPTIONS.     In  one  beautifully  printed  octavo  volume,  with  four  exquisite 
colored  plates,  presenting  more  than  thirty  varieties  of  Syphilitic  Eruptions ;  extra  cloth,  $2  25. 


MEDICAL    AND  SCIENTIFIC  PUBLICATIONS. 


47 


New  and  inipioved  Edition — Now  Ready  (1859), 


A  PRACTICAL  TREATISE 

ON  THE  DISEASES  OF  CHILDREN. 

BY  D.  FRANCIS  CONDIE,  M.  D. 

FIFTH  EDITION,  REVISED  AND  ENLARGED. 

In  one  large  octavo  volume  of  nearly  eight  hundred  pages ;  leather,  $3  25. 

From  the  Author's  Preface. 

To  present  a  complete  and  faithful  exposition  of  the  pathology  and  therapeutics  of  the  mala- 
dies incident  to  the  earlier  stages  of  existence — a  full  and  exact  account  of  the  diseases  of  infancy 
and  childhood — has  been  the  aim  of  the  author  of  the  present  treatise.  For  the  furtherance  of 
this  object,  in  the  preparation  of  a  fifth  edition,  the  entire  work  has  been  subjected  to  a  careful 
and  thorough  revision;  a  considerable  portion  of  it  has  been  entirely  rewritten,  and  several  new 
chapters  have  been  added. 

In  the  different  sections  will  be  found  incorporated  every  important  observation  in  reference 
to  the  diseases  of  which  they  treat,  that  lias  been  recorded  since  the  appearance  of  the  last  edi- 
tion ;  and  in  the  several  new  chapters,  an  account  of  some  affections  omitted  in  former  editions, 
and  for  the  accurate  description  and  satisfactory  management  of  which  we  are  indebted  mainly 
to  the  labors  of  recent  observers. 


Tlie  value  of  works  by  native  authors  on  the  diseases 
which  the  physician  is  called  upon  to  combat,  will  be 
appreciated  by  all ;  and  the  work  of  Dr.  Condie  has 
gained  for  itself  the  character  of  a  safe  guide  for  stu- 
dents, and  a  \iseful  work  for  consultation  by  those  en- 
gaged in  practice. — Nnu  York  Medical  Times. 

In  the  department  of  infantile  therapeutics,  the  work 
of  Dr.  Condie  is  considered  one  of  the  best  which  has 
been  published  in  the  English  language. — The  Stetho- 
scope. 

As  we  said  before,  we  do  not  know  of  a  better  book 
on  Diseases  of  Children,  and  to  a  large  part  of  its  re- 
commendations we  yield  an  unhesitating  concurrence. 
— Buffalo  Medical  Journal. 

The  work  of  Dr.  Condie  is  unquestionably  a  very 
able  one.  It  is  practical  in  its  character,  as  its  title 
imports;  but  the  practical  precepts  recommended  in 
it  are  based,  as  all  practice  should  be,  upon  a  familiar 
knowledge  of  disease.  The  opportunities  of  Dr.  Con- 
die for  the  practical  study  of  the  diseases  of  children 
have  been  great,  and  his  work  is  a  proof  that  they  have 
not  been  thrown  away.  He  has  read  much,  but  ob- 
served more;  and  we  think  that  we  may  safely  say 
that  the  American  student  cannot  tind,  in  his  own 
language,  a  better  book  upon  the  subject  of  which  it 
treats. — Am.  Journal  Medical  Sciences. 

To  call  the  attention  of  the  medical  fraternity  to  a 
new  edition  of  this  American  medical  classic,  seems 
almost  a  work  of  supererogation.  The  name  of  Dr. 
Condie  is  too  well  known,  and  his  influence  too  gene- 
rally felt  and  acknowledged  in  the  department  of  Pa- 
thology to  which  the  present  work  refers,  to  require 
other  than  a  very  brief  notice  of  this  new  edition. — 
The  Peninsxdar  Journal  of  Medicine. 


Taken  as  a  whole,  in  our  judgment.  Dr.  Condie's 
Treatise  is  one  from  the  perusal  of  which  the  practi- 
tioner in  this  country  will  rise  with  the  greatest  sa- 
tisfaction.—  Western  Journal  of  Medicitie  and  Surgery. 

One  of  the  best  works  upon  the  Diseases  of  Children 
in  the  English  language. —  Western  Lancet. 

We  feel  assured  from  actual  experience  that  no  phy- 
sician's library  can  be  complete  without  a  copy  of  this 
work. — iV".  T.  Jounial  of  Medicine. 

Perhaps  the  most  full  and  complete  work  now  before 
the  profession  of  the  United  States;  indeed,  we  may 
say  in  the  English  language.  It  is  vastly  superior  to 
most  of  its  predecessors. — Transylvania  Med.  Journal. 

A  veritable  ptediatric  encyclopedia,  and  an  honor 
to  American  medical  literature. —  Ohio  Medical  and 
Surgical  Journal. 

The  author's  great  experience,  extensive  reading, 
and  familiarity  with  foreign  languages,  peculiarly  fit 
him  for  the  execution  of  such  a  work ;  and  its  value 
is  abundantly  proved  by  the  numerous  editions  which 
it  has  reached  in  a  very  short  period.  It  is  character- 
ized by  great  clearness  and  lucidity  of  style  and  ar- 
rangement, sound  pathological  views,  and  precise 
and  plain  therapeutical  directions. — Medical  Examiner. 

To  the  American  practitioner.  Dr.  Condie's  remarks 
on  the  di.^eases  of  children  will  be  invaluable,  and  we 
accordingly  advise  those  who  have  failed  to  read  this 
work  to  procure  a  copy,  and  make  themselves  familiar 
with  its  sound  principles. — The  New  Orleans  Medical 
and  Surgical  Journal. 


LECTUKES  ON  THE 

DISEASES  OF  INFANCY  AND  CHILDHOOD. 

BY  CHARLES  WEST,  M.  D., 

Physician  to  the  Hospital  for  Sick  Children,  &c. 

Second  American,  from  the  Second  and  Enlarged  London  Edition. 

In  one  neat  octavo  volume  of  nearly  500  large  pages;  extra  cloth,  $2. 


In  taking  leave  of  Dr.  West,  we  can  scarcely  do  more 
than  reiterate  our  former  praise  of  him.  We  have 
given,  we  fear,  but  a  very  faint  notion  of  the  scope  of 
his  work,  and  of  its  excellent  execution.  It  is  one 
standing  by  itself  upon  its  important  subject  in  our 
language — unapproached,  unrivalled  His  knowledge 
of  what  others  have  done  is  equalled  only  by  his  own 
extensive  experience ;  and  the  results  of  both  are  com- 
bined in  his  valuable  practical  lectures  now  offered  for 
the  guidance  of  others. — Brit,  and  For.  Med.-Ckirurg. 
Jteview. 


The  book  has  about  it  that  practical  common  sense 
character  which  is  always  acceptable  to  the  practition- 
er of  medicine,  whilst  the  immense  experience  of  Dr. 
West,  derived  from  his  connection  with  the  London 
Hospital  for  Sick  Children,  gives  to  him  opportunities 
for  the  minute  observation  of  the  diseases  incident  to 
childhood,  such  as  no  private  practice  can  offer.  We 
would  especially  recommend  the  careful  study  of  these 
lectures  to  the  medical  student  who  is  preparing  him- 
self for  general  practice. —  Va  Med.  and  Surg.  Journal. 


48  BLANCHARD  AND  LEA'S 

New  and  Enlarged  Edition — (Just  Issued.) 

ON  THE  DISEASES  OF  INFANTS  AND  CHILDREN. 

BY  FLEETWOOD  CHURCHILL,  M.  D.,  M.  R.  I.  A., 

Author  of  "  Theory  and  Practice  of  Midwifery,"  '•  Diseases  of  Females,"  &e.  &c. 
Second  American  Edition,  Enlarged  and  Revised  by  the  Anthor. 

Edited,  ttith  Notes,  by  W.  V.  KEATING,  M.  D. 

In  one  large  and  handsome  octavo  volume  of  over  100  pages ;  leather,  $3  25;  extra  doth,  $3. 

The  thorough  manner  in  which  Dr.  Churchill  has  revised  this  work  may  be  estimated  from 
the  fact  that  not  only  has  a  considerable  portion  been  rewritten,  but  that  in  all  the  present  edition 
contains  about  one-third  more  matter  than  the  former.  Besides  an  enlargement  in  the  size  of  the 
page,  the  volume  has  been  increased  by  about  seventy-five  pages,  notwithstanding  which  the 
price  has  been  maintained  at  the  former  very  moderate  rate. 

Few  -works  devoted  to  the  same  subject  will  be  comes  to  us  with  its  value  greatly  enhanced,  not 
found,  in  fact,  to  excel  the  one  before  us,  in  extent  of  merely  by  bein<;  carefully  revi.-ed  throughout,  but 
research,  copiousness  of  reference,  and  fulness  and  also  by  the  addition  of  several  entire  chapters ;  on 
accuracy  of  detail.  It  will  constitute  a  valuable  and  Atelectasis  Pulmonum,  Pulmonary  Phthisis,  Tabes 
reliable  guide  to  the  knowledge  of  the  several  morbid  Mesenterica.  (Edema  of  the  Cellular  Tissue,  Typhoid 
conditions  incident  to  infancy  and  childhood,  their  Fever,  and  Infantile  Syphilis.  The  volume  is  a  most 
causes,  semeiology,  seats,  character,  and  progress,  and  valuable  addition  to  this  department  of  medical  sci- 
the  means  best  adapted  for  their  alleviation  and  cure,  ence. — Boston  Med.  and  Surg.  Jowtial,  Sept.  1856. 
equally  suitable  to  the  student,  as  to  the  practitioner  .       .  •.     ,  .        •. 

who  would  render  himself  familiar  with  the  lights  It  is  with  pleasure  we  notice  the  appearance  of  the 
which  recent  investigation  and  discoveries  have  second  edition  of  this  excellent  work  on  the  diseases 
thrown  upon  each  and  all  of  these  particulars.— J»i.  ,  of  Children.  It  has  been  carefully  revised  by  the  au- 
Journ.  Med.  Sciences.  Oct.  1856.  thor.  and  all  the  information  added  which  has  been  de- 

I  rived  from  recent  researches.    Every  paragraph,  says 

Dr.  Churchill  is  well  known  as  the  author  of  various  '  the  author,  has  been  carefully  gone  over  with  a  view 
works  on  obstetrics  and  the  diseases  of  women.  Like  to  correction,  and  suggestions  made  by  reviewers  have 
them,  this  contribution  to  infantile  therapeutics  is  been  carefully  weighed,  and  adopted  when  correct, 
especially  useful  for  the  careful  and  extensive  collec-  ^  Several  entire  new  chapters,  and  portions  of  chapters, 
tion  of  material  bearing  upon  the  subject.  As  a  book  '  have  been  added,  and  especial  reference  has  been  had 
of  reference,  it  will  be  often  sought  for,  whilst  its  emi-  to  American  authorities  so  as  to  adapt  it  to  the  wants 
nently  practical  character  will  make  it  an  admirable  of  this  country.  We  feel  that  it  is  no  more  than  jus- 
manual  for  the  student.  We  are  compelled  for  want  tice  to  add  our  recommendation,  most  cordially,  of  this 
of  space,  to  refrain  from  making  as  many  extracts  as  work,  as  being  among  the  best  we  have  on  this  sub- 
we  would  like  to  do,  and  will  close  our  notice  of  the  I  ject. — Cincinno.ti  Medical  Observer,  Oct.  1856. 
work  by  heartilv  recommending  it  both  to  the  student  I      „,     ,      ,   .    ^  ,,  ,    ,  ^     -,,  ^    ^        , 

and  the  practitioner.— Fu.  Med.  Journal,  Sept.  1856.  ^he  book  is  fully  posted  up  and  will  be  found  a  va- 

luable addition  to  the  practitioner  s  library. — Southern 

This  new  edition  of  the  work  of  a  favorite  author  |  Med.  and  Surg.  Journal,  Nov.  1856. 


A  TREATISE  ON  THE 

PHYSICAL  AXD  MEDICAL  TPiEAT3IENT  OF  CHEDREN. 

BY  WILLIAM  P.  DEWEES,  M.  D. 
Tenth  Edition. 

In  one  octavo  volume  of  548  pages ;  extra  cloth,  $2  80. 

Tenth  Edition. 

A    TREATISE    ON    THE    DISEASES    OF    FEMALES. 

BY  WILLIAM  P.  DEWEES,  M.  D. 

hi  one  octavo  volume  of  five  hundred  and  thirty-two  pages,  vAth  plates,  S'i  00. 

Just  Issued. 

ON  THE  CONSTITUTIONAL  TREATMENT 

OF  FEM:A.LE  I3ISEA.SES. 

BY   EDWARD   RIGBY,    M.  D., 

Senior  Physician  to  the  General  Lying-in  Hospital,  &c.;  Author  of  "A  System  of  Midwifery,"  &c. 
In  one  neat  royal  12mo.  volume  of  250  pages;  extra  cloth,  $1. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


49 


New  axid  Improved  Edition— Now  Ready  (June,  1859). 

¥OMA¥;  HER  DISEASES  AND  REMEDIES. 

A  SERIES  OF  LETTERS  TO   HIS   CLASS. 
BY  CHARLES  D.  MEIGS,  M.  D., 

Professor  of  Midwifery,  and  Diseases  of  Women  and  Cliildren,  in  the  Jefferson  Medical  College,  Philadelphia. 
FOURTH  EDITION,    REVISED. 
hi  one  large  and  liandsome  octavo  volume  of  over  seven  hundred  fages  ;  leather^  $3  60. 
The  gratifying  appreciation  of  his  labors,  as  evinced  by  the  exhaustion  of  three  large  impres- 
sions of  this  work,  has  not  been  lost  upon  the  author,  wtio  has  endeavored  in  everj'  way  to  ren- 
der it  worthy  of  the  favor  with  which  it  has  been  received.     The  opportunity  thus  afforded  for 
another  revision  has  been  improved,  and  the  work  is  now  presented  as  in  every  way  superior  to 
its  predecessors,  additions  and  alterations  having  been  made  wherever  the  advance  of  science 
has  rendered  them  desirable.     The  typographical  execution  of  the  work  will  also  be  found  to 
have  undergone  a  similar  improvement,  and  the  volume,  it  is  hoped,  will  be  found  in  all  respects 
worthy  to  maintain  the  position  it  has  acquired  as  the  standard  American  text-book  on  the  Dis- 
eases oi  Females.     A  few  notices  of  the  previous  editions  are  appended. 

On  its  first  appearance  we  had  occasion  to  speak  of 
it  in  terms  of  merited  commendation.  In  announcing 
the  third  edition,  it  is  only  necessary  to  say  that  it 
has  been  thoroughly  revised  and  much  enlarged  by 
its  distinguished  author  so  as  greatly  to  enhance  its 
value  and  usefulness. — St.  Louis  Med.  and  Surg.  Journ. 

Keplete  with  sound  practical  views,  and  evidently 
the  production  of  a  man  of  vast  experience  and  tho- 
roughly conversant  with  the  subject. — Medical  Chro- 
nicle. 


He  is  a  bold  thinker,  and  possesses  more  originality 
of  thought  and  style  than  almost  any  American  writer 
on  medical  subjects.  If  he  is  not  an  elegant  writer, 
there  is  at  least  a  freshness — a  raciness  in  his  mode 
of  expressing  himself— that  cannot  fail  to  draw  the 
reader  after  him  even  to  the  close  of  his  work ;  j'ou 
cannot  nod  over  his  pages;  he  stimulates  rather  than 
narcotises  your  senses,  and  the  reader  cannot  lay  aside 
these  letters  when  once  he  enters  into  their  merits. 
This  the  second  edition  is  much  amended  and  enlarged, 
and  affords  abundant  evidence  of  the  author's  talents 
and  industrj'. — N.  0.  Medical  and  Surgical  Journal. 

The  practical  writings  of  Dr.  Meigs  are  second  to 
none. — Ttie  N.  T.  Journal  of  Medicine. 

The  excellent  practical  directions  contained  in  this 
volume,  give  it  great  utility,  which  we  trust  will  not 
be  lost  upon  our  older  colleagues:  with  some  conden- 
sation, indeed,  we  should  tliink  it  well  adapted  for 
translation  into  German. — Zeitschriftfur  die  Gesammte 
Medecin. 

The  merits  of  the  first  edition  of  this  work  were  so 
generally  appreciated,  and  with  such  a  high  degree  of 
favor  by  the  medical  profession  throughout  the  Union, 
that  we  are  not  surprised  in  seeing  a  second  edition  of 
it.  It  is  a  standard  work  on  the  diseases  of  females, 
and  in  many  respects  is  one  of  the  very  best  of  its 
kind  in  the  English  language.  Upon  the  appearance 
of  the  first  edition,  we  gave  the  work  a  cordial  recep- 
tion, and  spoke  of  it  in  the  warmest  terms  of  commen- 
dation. Time  has  not  changed  the  favorable  estimate 
we  placed  upon  it.  but  has  rather  increased  our  con- 


victions of  its  superlative  merits.  But  we  do  not  now 
deem  it  necessary  to  say  more  than  to  commend  this 
work,  on  the  diseases  of  women,  and  the  remedies  for 
them,  to  the  attention  of  those  practitioners  who  have 
not  supplied  themselves  with  it.  The  most  select 
library  would  be  imperfect  without  it. — The  Western 
Journal  of  Medicine  and  Surgery. 

There  is  an  off-hand  fervor,  a  glow  and  a  warm- 
heartedness infecting  the  effort  of  Dr.  Meigs,  which  is 
entirely  captivating,  and  which  absolutely  hurries  the 
reader  through  from  beginning  to  end.  Besides,  the 
book  teems  with  solid  instruction,  and  it  shows  the 
very  highest  evidence  of  ability,  viz.,  the  clearness 
with  which  the  information  is  presented.  We  know 
of  no  better  test  of  one's  understanding  a  subject  than 
the  evidence  of  the  power  of  lucidly  explaining  it. 
The  most  elementary,  as  well  as  the  obscurest  subjects, 
under  the  pencil  of  Prof.  Meigs,  are  isolated  and  made 
to  stand  out  in  such  bold  relief,  as  to  produce  distinct 
impressions  upon  the  mind  and  memory  of  the  reader. 
—  The  Charleston  Medical  Journal. 

That  he  has  succeeded  in  writing  a  readable  work, 
in  our  estimation,  we  have  the  best  practical  evidence 
in  the  fact,  that,  in  spite  of  a  deliberate  resolve  to 
postpone  its  perusal,  having  other  more  pressing 
matters  on  hand,  we  found  ourselves  taking  it  up  day 
after  day,  at  our  leisure  moments,  until  the  volume 
was  finished.  If  we  may  judge  of  others  by  our  own 
experience,  the  student  and  practitioner  will  find  it  an 
attractive  book.  The  character  of  the  work  is  infi- 
nitely more  pleasing  to  us  than  if  written  in  a  tame, 
spiritless  manner,  albeit,  in  the  latter  case,  it  were  less 
obnoxious  to  criticism.  We  like  to  see  the  man  in  the 
book.  It  shows  the  author  to  be  a  scholar,  a  man  of 
genius,  and  as  regards  matter,  when  it  is  considered 
that  Prof  M.  ranks  among  the  most  talented  and 
learned  of  the  profession  of  this  country,  and,  we  may 
safely  add,  of  any  country,  and,  moreover,  that  his 
experience  in  his  particular  province  has  been  im- 
mense, it  can  hardly  appear  otherwise  than  that  what 
he  may  write  on  the  diseases  of  females  shall  be  de- 
serving of  most  respectful  attention. — Buffalo  Medical 
Journal. 


By  the  same  Author. 

A  TREATISE  ON  ACUTeTnD  CHROKIC  DISEASES 

OF  THE  NECK  OF  THE  UTERUS. 

With  numerous  Plates,  drawn  and  colored  from  Nature  in  the  highest  style  of  art. 
In  one  very  handsorae  octavo  volume  ;  extra  doth.,  $4  50. 


A    TREATISE    ON    THE 

DISEASES  AND  SPECIAL  HYGIENE  OE  EEMALES. 

By  CoLOMBAT  De  L'Isere.  Translated  from  the  French,  with  additions,  by  Charles  D.  Meigs, 
M.  D.,  Professor  of  Midwifery,  and  Diseases  of  Women  and  Children,  in  the  Jefferson  Medi- 
cal College,  Philadelphia.  A  new  and  revised  edition.  In  one  octavo  volume  of  over  700 
pages,  with  numerous  illustrations ;  extra  cloth,  $3  50. 

4 


50 


BLANCHARD   AND    I.EA'S 


Enlarged  and  Illustrated  Edition— Just  Issued. 


VERY    HANDSOME 

I  OCTAVO  VOLUME,  OF  OVER 

SEVEN   HUNDRED  AND  FIFTY 

LARGE  PAGES. 

WITH 

Numerous 

Illustrations. 

LEATHER, 

Price  $3  00. 


Prolapsus  Vkri. 


ON  THE  DISEASES  OF  WOMEN, 

mCLUDI^^G  DISEASES  OF  PREGNA^^CY  AND  CHILDBED. 

BY  FLEETWOOD  CHURCHILL,  M.  D.,  M.  R.  L  A., 

Author  of  "Diseases  of  Infants  and  Children,"  "Theory  and  Practice  of  Midwifery,"  &c  &c. 

Sixth  American  Edition,  extensively  Enlarged  and  Revised  by  the  Author. 

W.iX\  NotfS  anlJ  gLtilJitions 

BY  D.  FRANCIS  CONDIE,  M.  D  , 

Author  of  "A  Practical  Treatise  on  Diseases  of  Children,"  &c. 

On  no  former  edition  has  the  author  devoted  more  labor  to  render  the  work  a  complete  and 
satisfactory  resume  of  the  existing  state  of  knowledge  on  the  important  questions  under  con- 
sideration. To  effect  this,  extensive  additions  have  been  required,  some  additional  chapters 
inserted,  and  many  portions  rewritten  A  handsome  series  of  original  illustrations  of  the  more 
important  pathological  conditions  has  been  prepared,  while  the  mechanical  execution  of  the 
volume  will  be  found  greatly  superior  to  any  former  edition. 


Former  editions  of  this  work  have  been  noticed  in 
previous  numbers  of  the  Journal.  The  sentiments  of 
high  commendation  expressed  in  those  notices,  have 
only  to  be  repeated  in  this :  not  from  the  fact  that  the 
profession  at  large  are  not  aware  of  the  high  merits 
which  this  work  really  possesses,  but  from  a  desire  to 
see  the  principles  and  doctrines  therein  contained 
more  generally  recognized,  and  more  universally  car- 
ried out  in  practice. — N.  Y.  Journal  of  Medicine. 

We  know  of  no  author  who  deserves  that  approba- 
tion, on  "  the  diseases  of  females,"  to  the  same  extent 
that  Dr.  Oh  archill  does.  His,  indeed,  is  the  only  tho- 
rough treatise  we  know  of  on  the  subject;  and  it  may 
be  commended  to  practitioners  and  students  as  a  mas- 
terpiece in  its  particular  department.  The  former 
editions  of  this  work  have  been  commended  strongly 
in  this  journal,  and  they  have  won  their  way  to  an 
extended,  and  a  well-deserved  popularity.  This  fifth 
edition,  before  us,  is  well  calculated  to  maintain  Dr. 


Churchill's  high  reputation.  It  was  revised  and  en- 
larged by  the  author,  for  his  American  publishers, 
and  it  seems  to  us  that  there  is  scarcely  any  species  of 
desirable  information  on  its  subjects  that  may  not  be 
found  in  this  work. — The  We^te,rn  Journal  of  Medicine 
and  Surgery. 

"We  are  gratified  to  announce  a  new  and  revised  edi- 
tion of  Dr.  Churchill's  valuable  work  on  the  diseases 
of  females.  We  have  ever  regarded  it  as  one  of  the 
very  best  works  on  the  subjects  embraced  within  its 
scope,  in  the  English  language;  and  the  present  edi- 
tion, enlarged  and  revised  by  the  author,  renders  it 
still  more  entitled  to  the  confidence  of  the  profession. 
— The  Western  Lo.ncet. 

As  a  comprehensive  manual  for  students,  or  a  work 
of  reference  for  practitioners,  we  only  speak  with  com- 
mon justice  when  we  say  that  it  surpasses  any  other 
that  has  ever  issued  on  the  same  subject  from  the 
British  press. —  Ttie  Dublin  Quarterly  Journal. 


By  the  same  Author. 

ESSAYS  ON  THE  PUERPERAL  FEVER,  AND  OTHER  DISEASES  PECULIAR  TO 
WOMEN.  Selected  from  the  writings  of  Briti-h  Authors  previous  to  the  close  of  the  Eight- 
eenth Century.     In  one  neat  octavo  volume,  of  about  450  pages,  extra  cloth,  $2  50. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


51 


MEIGS  ON  PUERPERAL  FEVER— (Lately  Published.) 

ON  THE  NATURE,  SIGNS,  AND  TREATMENT 

OF  CHILDBED  FEVERS: 

IN  A  SERIES  OF  LETTERS  ADDRESSED  TO  THE  STUDENTS  OF  HIS  CLASS. 
BY  CHARLES  D.  MEIGS,  M.  D., 

Professor  of  Midwifery  and  Diseases  of  Women  and  Children  in  the  Jefferson  Medical  College,  Philadelphia. 
hi  07ie  very  liandsome  octavo  volume  of  362  pages  ;  extra  cloth,  $2  50. 


The  author,  a  practitioner  of  more  than  forty  years, 
has  collected  the  best  and  most  reliable  opinions  of 
many  writers  on  this  disease,  and  applying  to  them 
the  test  of  clinical  experience,  has  produced  a  volume 
superior  in  many  respects  to  any  which  has  heretofore 
come  from  his  pen  As  the  results  of  a  critical  inquiry 
into  the  literature  of  the  disease  and  a  large  and  long 
experience  in  practice,  this  volume  will  be  received  by 
the  profession  with  distinguished  favor,  and  we  feel 
warranted  in  commending  it  to  the  favorable  attention 
of  our  readers. — N.  Y.  Journal  of  Medicine. 

The  present  is  upon  one  of  the  most  diflBcult  subjects 
in  obstetrics,  and  we  feel  bound  to  say  that  as  a  whole 
it  is  superior  to  any  other  work  upon  the  same  subject. 
— Edinburgh  Med.  Journal. 


We  cordially  recommend  it  to  our  readers  as  a  work 
abounding  in  practical  good  sense,  and  sound  patho- 
logical and  therapeutical  views. — Si.  Louis  Med.  and 
Surg.  Journal. 

The  instructive  and  interesting  author  of  this  work, 
whose  previous  labors  in  the  department  of  medicine 
which  he  so  sedulously  cultivates,  have  placed  his 
countrymen  under  deep  and  abiding  obligations,  again 
challenges  their  admiration  in  the  fresh  and  vigorous, 
attractive  and  racy  pages  before  us.  It  is  a  delectable 
book.  *  *  *  This  treatise  upon  childbed  fevers 
will  have  an  extensive  sale,  being  destined,  as  it  de- 
serves, to  find  a  place  in  the  library  of  every  practi- 
tioner who  scorns  to  lag  in  the  rear  of  his  brethren. 
— Nashville  Journal  of  Medicine  and  Surgery. 


Just  Issued. 


ON  SOME  DISEASES  OF  WOMEN 

ADMITTING  OF  SURGICAL  TREATMENT. 

BY  ISAAC   BAKER  BROWN, 

Surgeon  Accoucheur  to  St.  Mary's  Hospital,  &c. 

WITH    HANDSOME    ILLUSTRATIONS. 

In  07ie  neat  octavo  volume,  extra  cloth,  of  two  hundred  and  seventy-six 
pages,  $1  60. 

During  the  appearance  of  this  work  in  the  "Medical  News  and  Li- 
brary" for  1855  and  1856,  it  commanded  the  warmest  approbation  of 
the  profession.  To  the  practitioner  the  work  possesses  peculiar  import- 
ance as  treating-  fully  and  completely  of  a  class  of  accidents  and  diseases 
of  frequent  occurrence,  which  have  hitherto  received  but  little  attention 
from  writers  of  systematic  works.  Occupying  a  middle  ground  be- 
tween surgery  and  obstetrics,  the  authorities  on  each  subject  have  well- 
nigh  abandoned  them  to  the  consideration  of  the  other,  and  thus  they 
are  nowhere  to  be  found  treated  with  the  attention  to  which  their  import- 
ance is  entitled.  The  subjects  considered  in  extenso  are  Ruptured  Pe- 
rineum—Prolapse of  the  Vagina — Prolapse  of  the  Uterus — Vesico-Vagi- 
nal  Fistula — Recto- Vaginal  Fistula — Lacerated  Vagina — Polypus  of  the 
Uterus — Stone  in  the  Female  Bladder — Vascular  Tumor  of  the  Meatus 
Urinarius — Imperforate  Hymen — Encysted  Tumor  of  the  Labia — Dis- 
eases of  the  Rectum  arising  from  the  Uterus — Ovarian  Dropsy. 


Needle  for  Ruptured 
Peri7ieum . 


A  PRACTICAL  TREATISE  ON  THE  DISEASES  PECULIAR  TO  WOMEN. 

Illustrated  by  Cases  derived  from  Hospital  and  Private  Practice.  By  Samuel  Ashwell,  M-  D., 
Obstetric  Physician  and  Lecturer  to  Guy's  Hospital,  London.  Third  American,  from  the 
Ihird  and  Revised  London  edition.     In  one  octavo  volume  of  528  pages;  extra  cloth,  $3. 

The  most  useful  practical  work  on  the  subject  in  the 
English  language. — Boston  Med.  and  Surg.  Journal. 

The  most  able,  and  certainly  the  most  standard  and 
practical,  work  on  female  diseases  that  we  have  yet 
seen. — Medico-Chirurgical  Review. 

The  young  practitioner  will  find  it  invaluable,  while 
those  who  have  had  most  experience  will  yet  find 


something  to  learn,  and  much  to  commend,  in  a  book 
which  shows  so  much  patient  observation,  practical 
skill,  and  sound  sense. — British  and  Foreign  Med.  Re- 
view. 

We  commend  it  to  our  readers  as  the  best  practical 
treatise  on  the  subject  which  has  yet  appeared. — Lon- 
d<m  Lancet. 


52 


BLANCHARD    AND    LEA'S 


New  and  Enlarged  Edition — (Preparing.) 


Uterus  and  Lateral  Ligaments. 

A  PKACTICAL  TREATISE  ON  INFLAMMATION  OF  THE  UTERUS, 

ITS  CERVIX  AND  APPENDAGES; 

AND  ON  ITS  CONNECTION  WITH  UTERINE  DISEASE. 

BY  JAMES  HENRY  BENNET,  M.  D. 

New  and  much  enlarged  Edition;  preparing  by  the  author  for  publication  in  1859. 


The  best  treatise  of  the  kind  in  the  English  lan- 
guage, and  we  know  of  none  in  the  French  or  German 
that  are  equally  valuable.  It  certainly  is  no  small 
compliment  to  Dr.  Bennet,  that  his  treatise  is  pub- 
lished in  the  latter  countries,  and  that  a  fourth  edition 
has  been  called  for  and  issued  in  this  country.  It 
must  be  admitted  that  Dr.  Bennet's  writings  have 


served  to  mark  a  new  era  in  the  literature,  if  not  in 
the  pathological  doctrines  of  this  department  of  Medi- 
cine. In  point  of  general  accuracy  and  practical  va- 
lue, there  certainly  is  no  other  treatise  that  equals 
this.  No  physician's  library  can  be  complete  without 
the  incomparably  excellent  work  of  Dr.  Bennet. — 
JV.  Y.  Journal  of  Medicine. 


By  the  same  Author, 


A  REVIEW  OF  THE  PRESENT  STATE  OF  UTERINE  PATHOLOGY.    One 

small  volume,  octavo,  flexible  cloth,  50  cents. 

A  New  Work  on  Leucorrhcea— (Lately  Published.) 

THE  PATHOLOGY  AND  TREItMENT  OF  LEUCOKRH(EA. 


W.  TYLER  SMITH,  M.D., 

Physician -Accoucheur    to    St.    Mary's 
Hospital,  &c. 

With  handsome  Illustrations. 

In  one  beautifully  printed  8vo.  volume 
o/200  pages;  extra  cloth,  $1  50. 


We  decide  this  book  to  be  one  of  the 
most  useful  monographs  which  has  ap- 
peared in  this  country.  What  was  be- 
fore unutterable  confusion  in  regard  to 
its  subject  has  now  the  order,  regularity, 
and  harmony  of  a  most  beautiful  sci- 
ence. Dr.  Smith  has  placed  the  whole 
profession  directly,  and  mankind  indi- 
rectly, under  abiding  obligations. — 
Nashville  Journal  of  Medicine. 

We  hail  the  appearance  of  this  prac- 
tical and  invaluable  work,  therefore,  as 
a  real  acquisition  to  our  medical  litera- 
ture.— Medical  Gazette. 


Villi  of  Os  Uteri,  magnified  230  diameters. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


53 


Now  Complete— (October,  1858). 


LECTURES  ON  THE  DISEASES  OF  WOMEN. 

BY  CHARLES  WEST,  M.D., 

Author  of  "  Lectures  on  the  Diseases  of  Children;"  Aecoucheur  to  and  Lecturer  on  Midwifery  at  St.  Bartholo- 
mew's Hospital;  Physician  to  the  Hospital  for  Sick  Children,  &c. 

Now  coinplete  in  one  handsome  octavo  volume,  extra  cloth,  of  about  500  'pages  ;  $2  50. 

Also,  for  sale  separate.  Part  II.,  being  pp.  309  to  end,  with  Index,  Title  matter,  &c.    8vo.,  cloth, 

$1. 
Part  I.  will  no  longer  be  sold  separate. 

The  enviable  reputation  acquired  for  Dr.  West  by  his  former  writings  will  be  more  than  sus- 
tained by  the  present  volume.  His  large  experience  both  in  hospital  and  private  practice,  his 
just  and  reasonable  views  on  vexed  questions,  and  his  happy  faculty  of  conveying  information 
in  a  clear  and  precise  manner,  give  him  great  advantages  as  a  teacher,  and  the  unanimous  ver- 
dict of  the  profession  has  pronounced  that  he  has  made  the  best  use  of  these  advantages.  The 
first  portion  of  these  Lectures,  as  published  in  the  "Medical  News  and  Library"  for  1856 
and  1857,  at  once  attracted  the  most  favorable  attention,  and  was  regarded  as  one  of  the  best 
Works  for  both  student  and  practitioner  that  had  appeared  on  this  interesting  department  of 
medicine.  That  portion  constituted  a  complete  treatise  on  the  Diseases  of  the  Uterus.  The 
concluding  part,  now  ready,  treats  in  an  equally  thorough  and  satisfactory  manner  of  the  Ute- 
rine Appendages,  the  Ovaries,  Vagina,  Bladder,  and  External  Organs;  and,  taken  toge- 
ther, they  form,  in  one  neat  volume,  a  clear  and  compendious  text-book  on  the  special  di.seases 
to  which  the  female  is  liable. 

|^°  Copies  of  Part  II.,  done  up  in  paper  covers,  for  mailing,  will  be  sent,  free  of  postage,  to  any 
address  within  the  United  States  on  receipt  of  One  Dollar  in  current  funds  or  postage  stamps. 
Subscribers  to  the  "Mb-dical  News  and  Library"  who  received  the  lirst  portion  of  this 
work  as  published  in  1856  and  1857,  should  lose  no  time  in  securing  the  completion. 
A  few  notices  of  Part  I.  are  added. 


As  a  writer,  Dr.  West  stands,  in  our  opinion,  second 
only  to  Watson,  the  ''Maeaulay  of  Medicine;"  he  pos- 
sesses that  happy  faculty  of  clothing  instruction  in 
easy  garments;  combining  pleasure  with  protit,  he 
leads  his  pupils,  in  spite  of  the  ancient  proverb,  along 
a  royal  road  to  learning.  His  work  is  one  which  will 
not  satisfy  the  extreme  on  either  side,  but  it  is  one 
that  will  please  the  great  majority  who  are  seeking 
truth,  and  one  that  will  convince  the  student  that  he 
has  committed  himself  to  a  candid,  safe,  and  valuable 
guide.  We  anticipate  with  pleasure  the  appearance 
of  the  second  part  of  the  work,  which,  if  it  equals  this 
part,  will  complete  one  of  our  very  best  volumes  upon 
diseases  of  females. — N.  A.  Med.-Chirurg.  Review,  Ju- 
ly, 1858. 

We  must  now  conclude  this  hastily  written  sketch 
with  the  confident  assurance  to  our  readers  that  the 
work  will  well  repay  perusal.  The  conscientious, 
painstaking,  practical  physician  is  apparent  on  every 
page. — New  York  Journal  of  Medicine,  March,  185S. 

We  have  to  say  of  it,  brieHy  and  decidedly,  that  it 
is  the  best  work  on  the  subject  in  any  language ;  and 
that  it  stamps  Dr.  West  as  the/aa7e  princeps  of  British 
obstetric  authors. — Edinburgh  Medical  Journal. 


We  gladly  recommend  his  Lectures  as  in  the  high- 
est degree  instructive  to  all  who  are  interested  in  ob- 
stetric practice. — London  Lancet. 

We  know  of  no  treatise  of  the  kind  so  complete  and 
yet  so  compact. — Chicago  Medical  Journal,  Jan.  1858. 

A  fairer,  more  honest,  more  earnest,  and  more  reli- 
able investigator  of  the  many  diseases  of  women  and 
children  is  not  to  be  found  in  any  country. — Southern 
Medical  and  Surgical  Journal,  January,  1858. 

Happy  in  his  simplicity  of  manner  and  moderate 
in  his  expression  of  opinion,  the  author  is  a  sound 
reasoner  and  a  good  practitioner,  and  his  book  is  wor- 
thy of  the  hand.some  garb  In  which  it  has  appeared 
from  the  press  of  the  Philadelphia  publishers. — Vir- 
ginia Med.  Journal. 

We  must  take  leave  of  Dr.  West's  very  useful  work, 
with  our  commendation  of  the  clearness  of  its  style, 
and  the  industry  and  sobriety  of  judgment  of  which  it 
gives  evidence. — London  Med.  Times  and  Gazette. 

Sound  judgment  and  good  sense  pervade  every 
chapter  of  the  book.  From  its  perusal  we  have  de- 
rived unmixed  satisfaction. — Dublin  Quarterly  Journ. 


Recently  Issued. 

AN  ENQUIRY"  INTO  THE  PATHOLOGICAL  IMPORTANCE  OF  ULCERA- 
TION OF  THE  OS  UTERI.  By  Charles  West,  M.D.,  Author  of  "Lectures  on  the 
Diseases  of  Women,"  &c.    In  one  neat  volume,  small  Svo.,  extra  cloth,  $1. 


THE  CAUSES  AND  TREATMENT  OF  ABORTION  AND  STERILITY; 

Being  the  Result  of  an  Extended  Practical  Inquiry  into  the  Physiological  and  Morbid  Conditions 
of  the  Uterus.  By  James  Whitehead,  F.  R.  C,  S.,  &c.  Second  American  Edition.  In  one 
octavo  volume,  extra  cloth,  of  368  pages,  f  1  75. 


54 


BLANCHARD   AND  LEA'S 


Just  Issued. 
AN  EXPOSITION  OF  THE 

SIGNS  AND  SYMPTOMS  OF  PREGNANCY. 

WITH  SOME  OTHER  PAPERS  ON  SUBJECTS  CONNECTED  WITH  MIDWIFERY. 
BY  W.  F.  MONTGOMERY,  M.  D.,  M.  R.  I.  A., 

Professor  of  Midwifery  in  the  King  and  Queen's  College  of  Physicians  in  Ireland,  &c. 

FROM  THE  SECOND  AND  ENLARGED  ENGLISH  EDITION. 

Witli  T-tvo  Exquisite  Colored  Plates  and  nnmerons  'Wood-cuts* 

In  one  very  handsome  octavo  volume  of  about  &(iO  pages  j  extra  cloth,  S3  75. 


Cervix  Uteri  in  the  Seventh  Month. 


This  work,  which  has  attained  the  position  of  a  medical  classic, 
has  received  from  the  author  the  most  careful  and  thorough  revi- 
sion To  use  his  own  words — "  The  present  Treatise,  though  only 
another  edition  of  a  work  already  published,  may  be,  I  think,  with 
trul  h  regarded  as  almost  a  new  book ;  every  sentence  of  the  former 
having  been  carefully  revised,  and  the  quantity  of  new  matter  now 
added  being  more  than  equal  in  amount  to  the  entire  contents  of  the 
former  edition."  Translated  into  various  languages,  and  univer- 
sally regarded  as  the  highest  authority  on  the  interesting  questions 
discussed,  its  high  character  will  be  fully  maintained,  the  author 
having  exhausted  the  subject  in  all  its  bearings,  examining  it  with 
all  the  aids  of  the  most  recent  investigations,  assisted  by  his  own 
long  and  enlarged  experience. 

The  title  scarcely  does  justice  to  the  scope  of  the  work.  With 
the  exception  of  the  procedures  of  operative  midwifery,  almost 
everything  connected  wlh  pregnancj'  and  delivery  is  brought  un- 
der Consideration,  and  there  are  few  physicians  who  will  not  find 
in  its  pages  much  that  will  prove  of  value  in  the  every-day  practice 
of  their  profession.  Besides  the  full  consideration  of  the  principal 
subject  of  the  work,  there  are  special  chapters  on  the  Period  of 
Human  Gestation,  the  Signs  of  Deliv-ery,  and  Spontaneous  Ampu- 
tation and  other  Accidents  to  the  Fcetus  in  Utero,  the  latter  illus- 
trated with  numerous  figures. 

In  every  respect,  the  mechanical  execution  of  the  work  will  be 
found  worthy  of  its  distinguished  reputation. 


Spontaneous  Amputation  in  Clero. 


MEDICAL    AND    SCIENTIFIC    P  LT  BLIC  A  TIONS. 


55 


New  and  Improved  Edition— (Lately  Issued.) 


In  one  large 

and  very  handsome 

imperial  octavo  volume 

of  six  hundred  and 

fifty  pages, 

with  sixty-four  plates, 

and  numerous 
wood-cuts  in  the  text, 

containing  in  all 
nearly  200  large  and 
beautiful  figures, 
strongly  bound  in 
leather,  with  raised 
bands;  price  $5. 


Tivins  in  Utero. 

THE    PRINCIPLES    AND    PRACTICE    OF 

OBSTETRIC  MEDICINE  AND  SURGERY, 

IN    REFERENCE  TO   THE   PROCESS   OF    PARTURITION. 
BY  FRANCIS  H.  RAMSBOTHAM,  M.  D. 

A  NEW  AND  ENLARGED  EDITION,  THOROUGHLY  REVISED  BY  THE  AUTHOR. 

With  Additions  by  W.  V.  KEATING,  M.  U. 

In  calling  the  attention  of  the  profession  to  the  new^  edition  of  this  standard  work,  the  pub- 
lishers would  remark  that  no  efforts  have  been  spared  to  secure  for  it  a  continuance  and  exten- 
sion of  the  remarkable  favor  with  which  it  has  been  received.  The  last  London  issue,  which 
was  considerably  enlarged,  has  received  a  further  revision  from  the  author,  especially  for  this 
country.  Its  passage  through  the  press  here  has  been  supervised  by  Dr.  Keating,  who  has  made 
numerous  additions  with  a  view  of  presenting  more  fully  whatever  was  necessary  to  adapt  it 
thoroughly  to  American  modes  of  practice,  and  in  its  mechanical  execution,  a  similiar  superio- 
rity over  former  editions  will  be  found. 


From  Prof.  Hodge,  of  the  University  of  Pennsylvania. 
To  the  American  public,  it  is  most  Taluable.  from 
its  intrinsic  undoubted  excellence,  and  as  being  the 
best  authorized  exponent  of  British  Midwifery.  Its 
circulation  will,  I  trust,  be  extensive  throughout  our 
country. 

But  once  in  a  long  time  some  brilliant  genius  rears 
his  head  above  the  horizon  of  science,  and  illuminates 
and  purities  every  department  that  he  investigates; 
and  his  works  become  types,  by  which  innumerable 
imitators  model  their  feeble  productions.  Such  a  genius 
■we  find  in  the  younger  Ramsbotham,  and  such  a  type 
•we  find  in  the  work  now  before  us.  The  binding,  pa- 
per, type,  the  engravings  and  wood-cuts  are  all  so  ex- 
cellent as  to  make  this  hook  one  of  the  finest  specimens 
of  the  art  of  printing  that  have  given  such  a  world- 


wide reputation  to  its  enterprising  and  liberal  publish- 
ers. We  welcome  Kamsbotham's  Principles  and  Prac- 
tice of  Obstetric  Medicine  and  Surgery  to  our  library, 
and  confidently  recommend  it  to  our  readers,  with  the 
assurance  that  it  will  not  disappoint  their  most  san- 
guine expectations. —  Western  Lancet. 

The  publishers  have  shown  their  appreciation  of  the 
merits  of  this  work  and  secured  its  success  by  the  truly 
elegant  style  in  which  they  have  brought  it  out,  ex- 
celling themselves  in  its  production,  especially  in  its 
plates.  It  is  dedicated  to  Prof.  Meigs,  and  has  the  em- 
phatic endorsement  of  Prof  Hodge,  as  the  best  expo- 
nent of  British  Midwifery.  We  know  of  no  text-book 
which  deserves  in  all  respects  to  he  more  highly  re- 
commended to  students,  and  we  could  wish  to  see  it 
in  the  hands  of  every  practitioner,  for  they  will  find  it 
invaluable  for  reference. — Med.  Gazette. 


56 


BLANCHARD  AND  LEA'S 


New  and  Improved  Edition — (Just  Issued.) 

OBSTETRICS; 

THE   SCIENCE  A-ND   THE   J^TiT. 

BY    CHAKLES   D.    MEIGS,    M.  D., 

Professor  of  Midwifery  and  Diseases  of  Women  and  Children  in  Jefferson  Medical  College,  of  Philadelphia. 

THIRD    EDITION,    REVISED. 

With  one  hundred  and  twenty-nine  Illuslratious. 

In  one  large  and  handsome  octavo  volume,  of  over  150  pages,  leather,  $3  75. 


Section  of  Pelvic  Viscera. 


The  rapid  demand  for  another  edition  of  this  work  is  a  sufficient  expression  of  the  favorable 
verdict  of  the  profession.  In  thus  preparing  it  a  third  time  for  the  press,  the  author  has  endea- 
vored to  render  it  in  every  respect  worthy  of  the  favor  which  it  has  received.  To  accomplish 
this  he  has  thoroughly  revised  it  in  every  part.  Some  portions  have  been  rewritten,  others 
added,  new  illustrations  have  been  in  many  instances  subf^tituted  for  such  as  were  not  deemed 
satisfactory,  while,  by  an  alteration  in  the  typographical  arrangement,  the  size  of  the  work  has 
not  been  increased,  and  the  price  remains  unaltered.  In  its  present  improved  form,  it  is,  there- 
fore, hoped  that  the  work  will  contmue  to  meet  the  wants  of  the  American  profession  as  a 
sound,  practical,  and  comprehensive  System  of  Midwifery. 


MEDICAL    AND    SCIENTIFIC    PUBLICATIONS. 


57 


A  NEW  OBSTETEICAL  TEXT-BOOK.— (Just  Issued,  1858.) 

THE  PRINCIPLES  AND  PRACTICE  OF  OBSTETRICS; 

INCLUDING  THE  TREATMENT  OF  CHRONIC  INFLAMMATION   OF  THE  UTERUS.  CON- 
SIDERED AS  A  FREQUENT  CAUSE  OF  ABORTION. 

By  henry  miller,  M.D., 

Professor  of  Obstetric  Medicine  in  the  Medical  Department  of  the  University  of  Louisville,  &c. 

WITH  ILLUSTRATIONS  ON   WOOD. 

In  one  handsome  octavo  volume  q/"  624  pages;  leather,  price  $3  75. 

The  reputation 
of  Dr.  Miller  a.<  an 
obstetrician  is  too 
widely  spread  to 
require  the  pub- 
lishers to  ask  the 
attention  of  the 
profession  special- 
ly to  a  volume 
containing  the  ex- 
perience of  his 
long  and  extensive 
practice.  The  ve- 
ry favorable  recep- 
tion accorded  to  his 
"Treatise  on  Hu- 
man Parturition," 
issued  some  years 
since,  is  an  earnest 
that  the  present 
work  will  fulfil  the 
author's  intention 
of  providing  with- 
in a  moderate  com- 
pass a  complete 
and  trustworthy 
text-book  for  the 
student,  and  book 
of  reference  for 
the  practitioner. 
Based  to  a  certain 
extent  upon  the 
former  work,  but 
enlarged  to  more 
than  double  its 
size,  and  almost 
wholly  rewritten, 
it  presents,  besides 
the  matured  expe- 
rience of  the  au- 
thor, the  most  re- 
cent views  and  investigations  of  modern  obstetric  writers,  such  as  Dubois,  Cazeaux,  Simpson, 
Tyler  Smith,  &c.,  thus  embodying  the  results  not  only  of  the  American,  but  also  of  the  Paris, 
the  London,  and  the  Edinburgh  obstetric  schools.  The  author's  position  for  so  many  years  as 
a  teacher  of  his  favorite  branch,  has  given  him  a  familiarity  with  the  wants  of  students  and  a 
facility  of  conveying  instruction,  which  cannot  fail  to  render  the  volume  eminently  adapted  to 
its  purposes. 


Internal  face  of  Uterus,  after  delivery. 


To  fiillow  the  many  tempting  leads  offered  in  this 
work  would  be  an  impossibility,  with  the  limits  here 
assigned,  and  the  cursory  character  of  the  notice  can  be 
the  more  readily  reconciled  to  the  reviewer's  mind,  as 
he  can  heartily  recommend  the  book,  not  in  the  hack- 
neyed phrase  as  one ''without  which  no  physician's 
library  can  be  considered  complete,"  but  as  instruct- 
ive and  sugsrestive  to  the  student,  and  refreshing  to 
the  obstetrician,  from  its  manliness  and  the  straight- 
forward way  in  which  all  questions  interesting  to  the 
author  are  met. — N.  T.  Journ.  of  Med.,  Sept.  1S58. 

In  conclusion,  we  can  only  express  our  regret  that 
we  cannot  do  full  justice  to  this  e.xcellent  book,  by 
presenting  larger  extracts,  in  an  extended  review. 
We  can  only  now  say  that,  we  have  derived  much 
pleasure  anil  benefit  from  its  perusal,  and  that  we 
cordially  recommend  it  to  the  profession,  both  to  prac- 
titioners and  to  pupils. — Southern  Medical  and  Surgi- 
cal Journal,  Aug.  1858. 

A  work  which  is  well  deserving  of  being  ranked 
among  the  very  best  treatises  on  this  important  branch 


of  medicine.  As  an  American  book,  we  commend  it 
to  the  special  favor  of  our  readers — not  so  much,  how- 
ever, on  account  of  its  domestic  origin  as  for  its  real 
merit. — St.  Louis  Med  and  Surg.  Journ.,  March,  1858. 

Destined  to  assume  a  high  and  permanent  rank 
among  the  standard  American  treatises  on  the  theory 
and  practice  of  midwifery.  It  is  not  only  generally 
full,  correct,  clear,  and  distinct  in  its  teachings,  but 
it  presents  a  manly  vigor  and  directness  in  the  hand- 
ling of  all  the  questions  embraced  within  its  general 
subject,  that  cannot  fail  to  impart  themselves,  in  some 
extent,  at  least,  to  its  readers;  inducing  them,  in  their 
turn,  to  examine,  think,  and  decide  for  themselves.— 
N.  A.  Medico-Chirurgical  Review,  May,  1858. 

On  account  of  its  sound  practical  value,  great  clear- 
ness, and,  in  most  portions,  conciseness,  we  do  not 
hesitate  to  commend  it  both  to  the  young  student  and 
to  the  old  practitioner,  and  we  believe  there  are  but 
few  even  of  the  latter  class  who  will  not  acknowledge 
that  tbey  have  been  much  instructed  as  well  as  en- 
tertained by  its  perusal. — Charleston  Med.  Jownal  and 
Review,  May,  1858. 


58 


BLANCHARD    AND    LEA'S 


THE  STUDENT'S  TEXT-BOOK  OF  MIDWIFERY. 


In  one 

very  handsome 

octavo  volume 

of  over 

five  hundred  pages, 

with 

one  hundred  and 

thirty-nine 

beautiful  wood  engravings; 

leather,  price  $3. 


Application  of  the  Long  Forceps. 


ON  THE  THEORY  AND  PRACTICE  OF  MIDWIFERY. 

BY  FLEETWOOD  CHURCHILL,  M.  D.,  M.  R.  I.  A., 

Author  of  "A  Treatise  on  Diseases  of  Females,"  "Infants  and  Children,"  &c. 

A  NEW   AMERICAN,   FROM  A  LATE  AND  IMPROVED  ENGLISH  EDITION. 

With  Notes  and  Additions  by  D.  F.  CONDIE,  M.D. 


To  bestow  praise  on  a  book  that  has  received  such 
marked  approbation  would  be  superfluous.  We  need 
only  say,  therefore,  that  if  the  first  edition  was  thought 
worthy  of  a  favorable  reception  by  the  medical  public, 
we  can  confidently  affirm  that  this  will  be  found  much 
more  so.  The  lecturer,  the  practitioner,  and  the  stu- 
dent, may  all  have  recourse  to  its  pages,  and  derive 
from  their  perusal  much  interest  and  instruction  in 
everything  relating  to  theoretical  and  practical  mid- 
wifery.— Dublin  Quartei-ly  Journal  of  Medical  Science.. 

A  work  of  very  great  merit,  and  such  as  we  can 
confidently  recommend  to  the  study  of  every  obstetric 
practitioner. — London  Medical  Gazette.. 

This  is  certainly  the  most  perfect  system  extant.  It 
is  the  best  adapted  for  the  purposes  of  a  text-book,  and 
that  which  he  whose  necessities  confine  him  to  one 
book,  should  select  in  preference  to  all  others. — South- 
ern Medical  and  Surgical  Journal. 

The  most  popular  work  on  midwifery  ever  issued 
from  the  American  'press.— Charleston  Med.  Journal. 

Were  we  reduced  to  the  necessity  of  having  but  one 
work  on  midwifery,  and  permitted  to  choose,  we  would 
unhesitatingly  take  Churchill. —  Western  Med.  and 
Surg.  Journal. 


No  work  holds  a  higher  position,  or  is  more  deserving 
of  being  placed  in  the  hands  of  the  tyro,  the  advanced 
student,  or  the  practitioner. — Medical  Examiner. 

Previous  editions,  under  the  editorial  supervision  of 
Prof.  R.  M.  Huston,  have  been  received  with  marked 
favor,  and  they  deserved  it;  but  this,  reprinted  from 
a  very  late  Dublin  edition,  carefully  revised  and 
brought  up  by  the  author  to  the  present  time,  does 
present  an  unusually  accurate  and  able  exposition  of 
every  important  particular  embraced  in  the  depart- 
ment of  midwifery.  *  *  The  clearness,  directness,  and 
precision  of  its  teachings,  together  with  the  great 
amount  of  statistical  research  which  its  text  exhibits, 
have  served  to  place  it  already  in  the  foremost  rank  of 
works  in  this  department  of  remedial  science. — N.  O. 
Medical  and  Surgical  Journal. 

In  our  opinion,  it  forms  one  of  the  best  if  not  the 
very  best  text-book  and  epitome  of  obstetric  science 
which  we  at  present  possess  in  the  English  language. 
— Monthly  Journal  of  Medical  Science. 

Few  treatises  will  be  found  better  adapted  as  a  text- 
book for  the  student,  or  as  a  manual  for  the  frequent 
consultation  of  the  young  practitioner.  —  American 
Medical  Journal. 


DEWEES'S  COMPREHENSIVE  SYSTEM  OF  MIDWIFERY.     Illustrated 

by  occasional  oases  and  many  engravings.     Twelfth  edition,  with  the  author's  last  improve- 
ments and  corrections.    In  one  octavo  volume,  extra  cloth,  of  600  pages,  $3  20. 

A  SYSTEM  OF  MIDWIFERY.     By  Edward  Rigby,  M.D.,  Physician  to 

the  General  Lying-in  Hospital,  &c.     Second  American  edition,  with  Notes  and  additional 
Illustrations.    In  one  octavo  volume  of  422  pages ;  extra  cloth,  $2  50. 

ON  PARTURITION,  AND  THE  PRINCIPLES  AND  PRACTICE  OF 

OBSTETRICS.    By  W.  Tyler  Smith,  M.  D.,  Physician-Accoucheur  to  St.  Mary's  Hospi- 
tal, &c.     In  one  royal  12mo.  volume  of  400  pages ;  extra  cluth,  f  1  25. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


59 


SURGICAL   ANATOMY. 

BY  JOSEPH  MACLISE,  Surgeon. 

FORMING  ONE  VOLUME,  VERY  LARGE  IJIPERIAL  QUARTO. 
WITU 

^ktg-Jigljt  Inrgc  anb  ^plcnbib  ^lat^s  brafon  in  tljt  htst  stjrlc,  anb  bcautifwlljr  toloxzh. 

Containing  one  hundred  and  ninety  Figures,  many  of  them  the  size  of  life. 

TOGETHER   WITH    COPIOUS   AND   EXPLANATORY    LETTER- PRESS. 

Strongly  and  handsoTtiely  hound  in  extra  cloth,  being  one  of  the  clieapest  and  best  executed 
Surgical  works  as  yet  issued  in  this  country,  $11  00;  also,  in  leather,  $12  00. 

*^*  The  size  of  this  work  prevents  its  transmission  by  mail  as  a  vi^hole,  but  copies  are  furnished 
for  that  purpose,  in  live  parts,  done  up  in  stout  wrappers ;  price  $9  00. 


This  great  work  being  now  concluded,  the  publishers  confidently  present  it  to  the  attention 
of  the  profession  as  worthy  in  every  respect  of  their  approbation  and  patronage.  No  complete 
work  of  the  kind  has  yet  been  published  in  the  English  language,  and  it  therefore  will  supply 
a  want  long  felt  in  this  country  of  an  accurate  and  comprehensive  Atlas  of  Surgical  Anatomy 
to  which  the  student  and  practitioner  can  at  all  times  refer,  to  ascertain  the  exact  relative  posi- 
tion of  the  various  portions  of  the  human  frame  towards  each  other  and  to  the  surface,  as  well 
as  their  abnormal  deviations.  The  importance  of  such  a  work  to  the  student  in  the  absence  oi 
anatomical  material,  and  to  the  practitioner  when  about  attempting  an  operation,  is  evident ; 
while  the  price  of  the  book,  notwithstanding  the  large  size,  beauty,  and  finish  of  tlie  very  nu- 
merous illustrations,  is  so  low  as  to  place  it  within  the  reach  of  every  member  of  the  profession. 
The  publishers  therefore  confidently  anticipate  a  very  extended  circulation  for  this  magnificent 
work. 


One  of  the  greatest  artistic  triumphs  of  the  age 
in  Surgical  Anatomy.  —  British  American  Medical 
Journal. 

Too  much  cannot  be  said  in  its  praise;  indeed,  we 
have  not  language  to  do  it  justice. —  Ohio  Medical  and 
Surgical  Journal. 

The  most  admirable  surgical  atlas  we  have  seen. 
To  the  practitioner  deprived  of  demonstrative  dissec- 
tions upon  the  human  subject,  it  is  an  invaluable 
companion. — If.  J.  Medical  Jieporter. 

The  most  accurately  engraved  and  beautifully 
colored  plates  we  have  ever  seen  in  an  American 
book — one  of  the  best  and  cheapest  surgical  works 
ever  published. — Buffalo  Medical  Journal. 

It  is  very  rare  that  so  elegantly  printed,  so  well  il- 
lustrated, and  so  useful  a  work,  is  offered  at  so  mode- 
rate a  price. — Charleston  Medical  Journal. 

Its  plates  can  boast  a  superiority  which  places  them 
almost  beyond  the  reach  of  competition.  —  Medical 
Examiner. 

Every  practitioner,  we  think,  should  have  a  work 
of  this  kind  within  reach. —  Southern  Medical  and 
Surgical  Journal. 

No  such  lithographic  illustrations  of  surgical  re- 
gions have  hitherto,  we  think,  been  given. — Boston 
Medical  and  Surgical  Journal. 

As  a  surgical  anatomist,  Mr.  Maclise  has  probably 
no  superior. — British  and  Foreign  Medico-Ohirurgical 
Jteview. 

Of  great  value  to  the  student  engaged  in  dissecting, 
and  to  the  surgeon  at  a  distance  from  the  means  of 
keeping  up  his  anatomical  knowledge. — Medical  Times. 

The  mechanical  execution  cannot  be  excelled. — 
Transylvania  Medical  Journal. 

A  work  which  has  no  parallel  in  point  of  accuracy 
and  cheapness  in  the  English  language. — N.  Y.  Journal 
of  Medicine. 

No  practitioner  whose  means  will  admit  should  fail 
to  possess  it. — Banking's  Abstract. 

Country  practitioners  will  find  these  plates  of  im- 
mense value. — JV.  Y.  Medical  Gazette. 


To  all  engaged  in  the  study  or  practice  of  their  pro- 
fession, such  a  work  is  almost  indispensable. — Dublin 
Quarterly  Medical  Journal. 

We  are  extremely  gratified  to  announce  to  the  pro- 
fession the  completion  of  this  truly  magnificent  work, 
which,  as  a  whole,  certainly  stands  unrivalled,  both 
for  accuracy  of  drawing,  beauty  of  coloring,  and  all 
the  requisite  explanations  of  the  subject  in  hand.  To 
the  publishers,  the  profession  in  America  is  deeply 
indebted  for  placing  such  a  valuable,  such  a  useful 
work,  at  its  disposal,  and  at  such  a  moderate  price.  It 
is  one  of  the  most  finished  and  complete  pictures  of 
Surgical  Anatomy  ever  off'ered  to  the  profession  of 
America.  With  these  plates  before  them,  the  student 
and  practitioner  can  never  be  at  a  loss,  under  the 
most  desperate  circumstances.  We  do  not  intend 
these  for  commonplace  compliments.  We  are  sincere ; 
because  we  know  the  work  will  be  found  invaluable 
to  the  young,  no  less  than  the  old,  surgeon. — The  New 
Orleans  Medical  and  Surgical  Journal. 

This  is  by  far  the  ablest  work  on  Surgical  Anatomy 
that  has  come  under  our  observation.  We  know  of 
no  other  work  that  would  justify  a  student,  in  any 
degree,  for  neglect  of  actual  dissection.  A  careful 
study  of  these  plates,  and  of  the  commentaries  on 
them,  would  almost  make  an  anatomist  of  a  diligent 
student.  And  to  one  who  has  studied  anatomy  by 
dissection,  this  work  is  invaluable  as  a  perpetual  re- 
membrancer, in  matters  of  knowledge  that  may  slip 
from  the  memory.  The  practitioner  can  scarcely  con- 
sider himself  equipped  for  the  duties  of  his  profession 
without  such  a  work  as  this — and  this  has  no  rival — 
in  his  library.  In  those  sudden  emergencies  that  so 
often  arise,  and  which  require  the  instantaneous  com- 
mand of  minute  anatomical  knowledge,  a  work  of  this 
kind  keeps  the  details  of  the  dissecting-room  perpetu- 
ally fresh  in  the  memory.  We  repeat  that  no  medical 
library,  however  large,  can  be  complete  without  Ma- 
clise's  Surgical  Anatomy.  The  American  edition  is 
well  entitled  to  the  confidence  of  the  profession,  and 
should  command,  among  them,  an  extensive  sale. 
The  investment  of  the  amount  of  the  cost  of  this 
work  will  prove  to  be  a  very  profitable  one,  and  if 
practitioners  would  qualify  themselves  thoroughly 
with  such  important  knowledge  as  is  contained  in 
works  of  this  kind,  there  would  be  fewer  of  them  sigh- 
ing for  employment. — The  Western  Journal  of  Medicine 
and  Surgery. 


1^°  The  very  low  price  at  which  this  work  is  furnished,  and  the  beauty  of  its  execution, 
require  an  extended  sale  to  compensate  the  publishers  for  the  heavy  expenses  incurred. 


60 


BLANCHARD   AND    LEA'S 


GROSS'  SURGERY— (To  be  ready  in  July,  1859.) 


Dislocaiion  of  the  Knee. 

A  SYSTEM  OF  SURGERY; 

Diagnostic,  Pathological,  Therapeutic,  and  Operative. 

BY  SAMTJEL  D.  GROSS,  M.D., 

Professor  of  Surgery  in  the  Jefferson  Medical  College  of  Philadelphia,  &c. 

WITH  OVER  SEVEN  HUNDRED  ILLUSTRATIONS: 

A  LARGE  NUMBER  OF  WHICH  ARE  FROM  ORIGINAL  DRAWINGS. 

Li  tvjo  very  large  octavo  vohtmes,  of  more  than  2000  closely  printed  'pages.,  strongly  bound  in 

leather.,  vnth  raised  hands. 

The  want  has  long  existed  of  a  complete 
American  System  of  Surgery — a  work  which 
should  present  the  experience  of  practitioners 
on  Ihis  side  of  the  Atlantic  as  well  as  of  those 
^  of  Europe  in  all  the  various  departments  of 
/  surg-ical  science.  To  accomplish  this  has  been 
the  author's  aim  in  the  present  work.  The 
thorough  execution  of  his  plan  has  required  a 
delay  far  beyond  what  was  originally  contem- 
plated, but  the  advantages  resulting  from  the 
increased  time  and  labor  thus  bestowed  upon 
it  will  be  evident  from  the  completeness  with 
which  he  has  thus  been  enabled  to  treat  all 
the  various  divisions  of  the  subject.  He  has 
thus  hoped  to  render  it  a  work  from  which 
the  student  can  derive  the  elementary  prin- 
ciples of  the  science,  while  the  mature  prac- 
titioner can  likewise  feel  assured  that  in  the 
emergencies  of  his  profession,  the  immense 
amount  of  practical  matter  and  important  de- 
tails embodied  in  its  pages  may  furnisti  him 
whatever  assistance  may  be  required  at  the 
moment.  With  this  view  the  work  has  not 
been  confined  to  the  usual  topics  treated  in 
the  ordinary  text-books,  but  the  subsidiary  branches  of  Surgery  have  received  the  attention  to 
which  their  importance  entitles  them.  'Thus,  Ophthalmic  and  Aural  Surgery,  the  Surgical 
Diseases  of  Females,  Fractures  and  Dislocations,  xMinor  Surgery,  Dentistry,  &:c.  &rc.,  have  been 
developed  with  a  fulness  of  which  the  object  has  been  to  furnish  all  that  the  wants  of  the  prac- 
tising surgeon  could  reasonably  require.  Such  being  the  design  of  the  work,  the  student  who 
procures  it  can  feel  that  he  does  not  merely  possess  a  guide  (or  his  preliminary  studies,  but  a 
copious  book  of  reference,  to  be  preserved  for  consultation  during  his  whole  professional  career. 
In  view  of  the  magnitude  and  importance  of  the  work,  the  publisters  have  spared  neither 
labor  nor  expense  to  "render  its  external  appearance  in  every  respect  unexceptionable,  and  to 
carry  out  fully  the  designs  of  the  author.  The  series  of  illustrations  is  fuller  and  more  complete 
than  has  hitherto  been  attempted  in  any  work  of  the  kind,  and  while  wood-cuts  have  been  un- 
sparingly selected  from  every  authoritative  and  accessible  source,  a  very  large  nurnber  of  ori- 
ginal drawings  have  been  prepared,  where  the  material  already  existing  was  unsatisfactory  or 
insufficient.  Printed  in  the  handsomest  manner,  with  new  and  clear  type,  on  fine  paper,  these 
volumes  are  therefore  offered  to  the  profession  with  the  hope  that  they  will  fully  meet  the  views 
of  the  most  exacting  and  fastidious ;  and  that  no  practitioner,  however  well  supplied  his  library 
may  be,  will  consider  it  complete  without  them. 


Ele'pho.  nt  iasts. 


MEDICAL  ANDSCIENTIFIC  PUBLICATIONS. 


61 


New  and  enlarged  edition — Now  Ready  (1859). 


THE  SCIENCE  AND  ART  OF  SURGERY. 


tontist  m\  .Surgical  Injuries,  §m$ts,  auij  6pi''ations. 

BY  JOHN  ERICHSEN, 

Professor  of  Surgery  in  University  College,  London,  &c. 

A  New  and  improved  American,  from  the  Second  enlarged  and  carefully  revised  English 

edition. 

ILLUSTRATED    BY   OVER   FO0R   HUNDRED    ENGRAVINGS  ON   'WOOD,    MANY  OF  WHICH    ARE    FROM 

NEW  SUBJECTS. 

In  one  very  large  and  handsome  octavo  volume,  of  1000  closely  pri')i?ecZ  lyages,  strongly  hound  in 
leather,  with  raised  bands  ;  price  $4  50. 


Lateral  Flap  Operation  of  the  Thigh. 

The  author  has  subjected  this  work  to  a  most  thorough  revision,  and  every  portion  will  be 
found  to  bear  the  marks  of  his  desire  to  render  it  an  exponent  of  the  most  advanced  condition 
of  surgical  science,  as  is  shown  by  the  very  considerable 
increase  in  its  s-ize,  and  in  the  number  of  illustrations. 
The  publishers  therefore  trust  that  it  will  be  found  to 
merit  a  continuance  of  the  very  remarkable  tavor  with 
which  it  has  been  received. 

The  present  edition  has  been  much  extended,  many  of  the 
chapters  entirely  rewritten,  and  upwards  of  160  new  illustrations 
liave  been  introduced.  Great  attention  has  been  paid  to  all  the 
modern  improTements  in  surgery,  especially  to  the  subject  of 
resection  of  joints,  which  is  most  fully  considered  and  illustrated. 
The  additions  to  the  work  are  almost  exclusively  of  a  practical 
character. — London  Lancet,  Oct.  17,  1S57. 

It  requires  no  small  power  of  condensation,  no  slight  tact  and 
judgment,  to  prepare  a  work  within  a  moderate  compass  on  so 
wide  a  subject  as  the  science  and  art  of  Surgery,  which  shall 
descend  with  sufficient  minuteness  into  practical  details  to  be- 
come useful  at  the  bedside,  and  at  the  same  time  shall  expound 
those  principles  which  are  to  guide  the  student  in  his  studies  of 
surgical  science.  Mr  Erichsen's  task  was  a  most  difficult  one, 
and  he  has  accomplished  it  in  a  manner  which  entitles  his  work 
to  a  place  beside  AVatson's  Lectures  on  the  sister  science  It 
would  not  be  easy  to  award  any  surgical  work  a  higher  meed  of 
praise. — London  Med.  Times  and  Gazette,  Oct.  31,  1857. 

It  is,  in  our  humble  judgment,  decidedly  the  best  book  of  the 
kind  in  the  English  language.  Strange  that  just  such  books  are 
not  oftener  produced  by  public  teachers  of  surgery  in  this  coun- 
try and  Great  Britain.  Indeed,  it  is  a  matter  of  great  astonish- 
ment, but  no  less  true  than  astonishing,  that  of  the  many  works 
on  surgery  republished  in  this  country  within  the  last  fifteen  or 
twenty  years  as  text^ books  for  medical  students,  this  is  the  only 
one  that  even  approximates  to  the  fulfilment  of  the  peculiar 
■wants  of  young  men  just  entering  upon  the  study  of  this  branch 
of  the  profession. —  Western  Journ.  of  Med.  and  Surgery. 

Embracing,  as  will  be  perceived,  the  whole  surgical  domain, 
and  each  division  of  itself  almost  complete  and  perfect,  each 
chapter  full  and  explicit,  each  subject  faithfully  exhibited,  we 
can  only  express  our  estimate  of  it  in  the  aggregate.  AVe  con- 
sider it  an  excellent  contribution  to  surgery,  as  probably  the 
best  single  volume  now  extant  on  the  subject,  and  with  great 
pleasure  we  add  it  to  our  text-books. — Nashville  Journ.  of  Med. 
and  Surgery. 


Starched  Bandage  Apparatus  for 
Fractured  Leg. 


62 


BLAN  CHARD  A^^D  LEA'S 


New  and  Improved  Edition — (Just  Issued.] 


Osleo  sarcoma  of  Femur. 


In  one 

large  and 

very  handsome 

octavo 

volume, 

of 

700  pages, 

vs'ith  I 

240  exquisite 

engraving's 

on 

wood. 

Bound  ia 

leather, 

83  75. 


THE 


Abscess  Viceralin^  into  Carotid. 


PRINCIPLES  OF  SURGERY. 

BY  JAMES  MILLER,  F.  K.  S.  E., 

Professor  of  Surgery  in  the  Tniversity  of  Edinburgh,  &c. 

<f  onrl^  g^meritan,  from  tbe  C^irb  anb  ^ebiscb  English  (fintion. 


The  extended  reputation  enjoyed  by  this 
work  will  be  fully  maintained  by  the  present 
edition.  Thoroughly  revised  by  the  author,  it 
will  be  found  a  clear  and  compendious  exposi- 
tion of  surgical  science  ia  its  most  advanced 
condition. 

In  connection  with  the  recently  issued  third 
edition  of  the  author's  "Practice  of  Surgery," 
it  forms  a  very  complete  system  of  Surgery  in 
all  its  branches. 

Miller's  Principles  of  Surgery  has  become  a  favorite 
standard  with  surgeons  wherever  the  English  language 
is  spoken,  and,  together  with  Miller's  Practice  of  .Sur- 
gery, constitute  a  surgical  library  for  all  practical 
purposes. — Nashville  JournoX  of  Merli/yine,  Sept.  1856. 

The  medical  student  who  does  not  intend  to  prac- 
tise operative  surgery,  nevertheless,  will  find  Prof. 
Millei^s  Principles  of  Surgery  one  of  the  best  books  as 
a  safe  guide  in  the  practice  of  physic,  not  to  say  Sur- 
gery. This  fourth  edition  of  Prof.  Miller's  Principles 
of  Surgery,  now  diligently  revised,  greatly  enlarged, 
abundantly  illustrated,  enriched  with  recent  facts, 
and  reasoned  out  of  the  authors  more  matured  and 
enlarged  experiences,  must  prove  acceptable  and  very 
necessary  to  both  physicians  and  surgeons  desirous  of 
keeping  pace  with  the  progress  of  medical  knowledge. 
— N.  0.  Med.  and  Surg.  Journal,  May,  1S56. 

On  these  accounts,  especially,  apart  from  the  well- 1 
known  elegance  and  clearness  of  language,  as  well  as 
comprehensive  range  of  topics  and  elevated  scientific 
tone  of  Prof  Miller's  treatise,  we  are  glad  to  believe 
that  its  high  position  as  one  of  the  acknowledged  ex- 
emplars of  the  Princijjles  of  Surgery-  perhaps  the 
best  of  its  class — ;,)  abundantly  maintained.  We 
heartily  commend  it  to  the  atteotion  of  pupils  and 


BMMi^^mi,.^. 


Simple  and  Compound  Cancer  Cells. 

practitioners  as  a  valuable  elementary  preceptor. 
They  may  safely  resort  to  it,  and,  within  the  limits  of 
a  text-book,  depend  upon  it  as  a  reliable  monitor  and 
guide  in  their  earlier  studies;  while  they  will  be  apt 
to  find  it,  along  with  works  of  greater  compass  and 
pretension,  no  mean  instructor  in  any  stage  of  a  pro- 
fessional career. — American  Journal  Med.  Sciences. 


MEDICAL   AND   SCIENTIFIC    PUBLICATIONS. 


63 


THE  PRACTICE  OF  SURGERY. 

BY  JAMES  MILLER,  F.  K.  S.  E., 

Professor  of  Surgery  in  the  University  of  Edinburgh. 
A  NEW  AND  REVISED  AMERICAN,  FROM  THE  LAST  ENGLISH  EDITION. 

5(iUtlj  obex  time  l^unirrcit  bjcatttxftil  |llti stations  an  SSoob. 

In  one  very  large  and  handsome  octavo  vohnrie,  of  over  seven  Inindred  pages  ;  leather,  $3  75. 
To  match  the  "Principles  of  Surgery." 


Ligatures  of  the  Posterior  Tibial. 


Pulypt  of  the  Face. 


By  the  almost  unanimous  voice  of  the  profession, 
his  works,  both  on  the  principles  and  practice  of  sur- 
gery, have  been  assigned  the  highest  rank.  If  ■we 
were  limited  to  but  one  work  on  Surgery,  that  one 
should  be  Millers,  as  we  regard  it  superior  to  all 
others. — St.  Loiiii  Med.  and  Surg.  Journal. 

The  author,  distinguished  alike  as  a  practitioner 
and  writer,  has  in  this  and  his''  Principles,"  presented 
to  the  profession  one  of  the  most  complete  and  reliable 
systems  of  Surgery  extant.  His  style  of  writing  is 
original,  impressive,  and  engaging,  energetic,  concise, 
and  lucid.  Few  have  the  faculty  of  condensing  so 
much  in  small  space,  and  at  the  same  time  so  persist- 
ently holding  the  attention;  indeed,  he  appears  to 
make  the  very  process  of  condensation  a  means  of 
producing  attractions.  Whether  as  a  test-book  for 
students  or  a  book  of  reference  for  practitioners,  it  can- 
not be  too  strongly  recommended. — Southern  Journal 
of  Medical  and  Physical  Science. 


No  encomium  of  ours  could  add  to  the  popularity  of 
Miller's  Surgery.  Its  reputation  in  this  country  is 
unsurpassed  by  that  of  any  other  work,  and,  when 
taken  in  connection  with  the  author's  Principles  of 
Surgery,  constitutes  a  whole,  without  reference  to 
which  no  conscientious  surgeon  would  be  willing  to 
practise  his  art. — Southern  Med.  and  Surg.  Journal. 

It  is  seldom  that  two  volumes  have  ever  made  so 
profound  an  impression  in  so  short  a  time  as  the 
"Principles"  and  the  " Practice"  of  Surgery,  by  Mr. 
Miller — or  so  richly  merited  the  reputation  they  have 
acquired.  The  author  is  an  eminently  sensible,  prac- 
tical, and  well-informed  man,  who  knows  exactly  what 
he  is  talking  about  and  exactly  how  to  talk  it. — Ken- 
tucky Medical  Recorder. 

The  two  volumes  together  form  a  complete  expose 
of  the-present  state  of  Surgery,  and  they  ought  to  be 
on  the  shelves  of  every  surgeon. — N.  J.  Medical  Re- 
porter. 


64 


BLANCHARD    AND    LEA'S 


THE  STUDENT'S  TEXT-BOOK  OF  SURGERY. 


With 

one  hundred  and 

ninety-three 

beautiful  illustrations 

on  wood; 

bound  in  leather; 

price  $3. 


In  one 

very  handsome 

octavo  volume  of 

nearly  six  hundred 

pages. 


Syphilitic  Caries  of  Skull. 

THE  PPiHCIPLES  AND  PEACTICE  OF  lODEPJ  SURGERY. 

BY  ROBERT  DRUTTT, 

Fellow  of  the  Royal  College  of  Surgeons. 

■  '^  mb  '^mtxkm,  from  a  Iat«  anb  intprobjir  IFonifon;  ©bition. 
Edited  by  F.  W.  SARGENT,  M.D., 

Author  of  "  Minor  Surgery,"  &c. 


The  author  has  evidently  ransacked  every  standard 
treatise  of  ancient  and  modern  times,  and  all  that  is 
really  practically  useful  at  the  bedside  will  be  found 
in  a  form  at  once  clear,  dislinct,  and  interesting. — 
Edinh.  Monthly  Med.  Journal. 


Bandage  for  Fractured  Jaw 


Druitt's  work,  condensed,  systematic,  lucid,  and 
practical  as  it  is,  beyond  most  works  on  Surgery  ac- 
cessible to  the  American  student,  has  had  much  cur- 
rency in  this  country,  and  under  its  present  auspices 
promises  to  rise  to  yet  higher  favor. — The  Western 
Journal  of  Medicine  and  Surgery. 

The  most  accurate  and  ample  r(5sume  of  the  present 
state  of  Sursery  that  we  are  acquainted  with. — Dub- 
lin Medical  Journal. 

A*hetter  book  on  the  principles  and  practice  of  Sur- 
gery as  now  understood  in  England  and  America,  has 
not  been  given  to  the  profession. — Boston  Medical  and 
Surgical  Journal. 

An  unsurpassable  compendium,  not  only  of  Surgi- 
cal, but  of  Medical  Practice. — London  Medical  Gazette. 

No  work,  in  our  opinion,  equals  it  in  presenting  so 
much  valuable  surgical  matter  in  so  small  a  compass. 
— St.  Louis  Medical  and  Surgical  Journal. 

This  work  merits  our  warmest  commendations,  and 
we  strongly  recommend  it  to  young  surgeons  as  an 
admirable  digest  of  the  principles  and  practice  of  mo 
dern  Surgery.— J/«ZicaZ  Gazette. 

It  may  be  said  with  truth  that  the  work  of  Mr.  Dru- 
itt  affords  a  complete,  though  brief  and  condensed 
view  of  the  entire  tield  of  modern  surgery.  Vi'e  know 
of  no  work  on  the  same  subject  having  the  appearance 
of  a  manual,  which  includes  so  many  topics  of  interest 
to  the  surgeon;  and  the  terse  manner  in  which  each 
has  been  treated  evinces  a  most  enviable  quality  of 
mind  on  the  part  of  the  author,  who  seems  to  have  an 
innate  power  of  searching  out  and  grasping  the  leading 
facts  and  features  of  the  most  elaborate  productions  of 
the  pen.  It  is  a  useful  handbook  for  the  practitioner, 
and  we  should  deem  a  teacher  of  surgery  unpardon- 
able who  did  not  recommend  it  to  his  pupils.  In  our 
own  opinion,  it  is  admirably  adapted  to  the  wants  of 
the  student. — Provincial  Med.  and  Surgical  Journal. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


65 


THE  PRINCIPLES  AND  PRACTICE  OF  SURGERY. 

BY  WILLIAM  PIRRIE,  F.  R.  S.  E., 

Regius  Professor  of  Surgery  in  the  University  of  Aberdeen,  Ac. 

Edited,  with  Additions,  by  JOHN  NEILL,  M.  D., 

Surgeon  to  the  Pennsylvania  Hospital,  Professor  of  Surgery  in  the  Penna.  Medical  College,  &c. 

In  one  large  and  handsome  octavo  volume  of  nearly  800  j)nges,  leather,  with  three  hundred  and  six- 
,.    teen  beautiful  illustrations  on  wood ;  price  $3  75. 

However  well  it 
may  be  adapted  for 
a  text-book  (and  in 
this  respect  it  may 
compete  with  the 
best  of  them),  of 
this  much  our  read- 
ing has  convinced 
us,  that,  as  a  sys- 
tematic treatise,  it 
is  carefully  and  ably 
written,  and  can 
hardly  fail  to  com- 
mand a  prominent 
position  in  the  li- 
brary of  practition- 
ers ;  though  not 
complete  in  the  full- 
est sense  of  the 
word,  it  neverthe- 
less furnishes  the 
student  and  practi- 
tioner with  as  con- 
cise and  chaste  a 
work  as  exists  in 
our  language.  The 
additions  to  the  vo- 
lume by  Dr.  Neill, 
are  judicious;  and 
while  they  render 
it  more  complete, 
greatly  enhance  its 
practical  value,  as  a 
work  for  practition- 
ers and  students. — 
N.  Y.  Jour,  of  Med. 

Our  impression  is 
that,  as  a  manual 
for  students,  Pir- 
rie's  is  the  best 
work  extant.—  West- 

Lateral  Operation  of  Lithotomy.  'Zr^^^;  "'"^  '^"'•^• 

c;,Y^  \^°^-  °l^°  °*^®'"  ^"'gi^al  work  of  a  reasonable  I  We  can  pronounce  it  to  be  one  of  the  best  treatises 
size,  wherein  there  is  so  much  theory  and  practice,  or  |  on  surgery  in  the  English  language.  We  very  strono^lv 
where  .subjects  are  more  soundly  or  clearly  taught-  I  recommend  this  excellent  work^  both  to  the  practi- 
1  ne  stetlioscope.  (  tioner  and  student.— Cajioda  Medical  Journal. 


OPERATIVE   SURGERY. 

BY  FREDERICK  C.  SKEY,  F.R.S. 

With  about  100  Engravings  on  Wood. 

In  one  handsome  octavo  volume  of  over  6b0  pages;  ex- 
tra cloth,  $3  25. 


_  We  cannot  withhold  from  this  work  our  high  commenda- 
tion. Students  and  practitioners  will  find  it  an  invaluable 
teacher  and  guide  upon  every  topic  connected  with  this  de- 
partment.—A'ew  York  Medical  Gazette. 

A  work  of  the  very  highest  importance— a  work  by  itself.— 
London  Meii.  Gazette. 


Ligature  of  the  Facial  Artery 


66 


BLANCHARD    AND    LEA'S 


Apforatusfor  Operation  for  Hare-Lip. 


Excision  of  Scapula. 


A  SYSTEM  OF  PRACTICAL  SURGERY. 

BY  WILLIAM  FERGUSSON,  F.  E.  S., 

Professor  of  Surgery  in  King's  College,  London. 

^ami\  %.rcitvi£wsi,  from  i\t  %\jixii  anir  ©niargeitr  ITonboit  ®bition. 

WITH   THREE    HUNDRED    AND    NINETY-THREE    ILLUSTRATIONS    ON    ■WOOD. 

I7i  one  large  and  very  handsome  octavo  volume,  of  over  600  pages,  leather,  $3  00. 


No  work  was  ever  written  which  more  nearly  com- 
prehended the  necessities  of  the  student  and  practi- 
tioner, and  was  more  carefully  arranged  to  that  single 
purpose,  than  this. — JV.  Y.  Med.  and  Surg.  Journal. 

The  addition  of  many  new  pages  makes  this  work 
more  than  ever  indispensable  to  the  student  and 
practitioner. — JSanking's  Abstract. 

For  the  general  practitioner  who  does  not  make  a 
specialty  of  surgery,  it  is  certainly  invaluable  The 
style  is  concise,  pointed,  and  clear.    The  descriptions 


of  the  various  operations  are  concentrated  and  accu- 
rate, so  that  in  cases  of  emergency,  the  principles  of 
the  most  difficult  operations  may  be  obtained  by  a 
reference  of  a  few  moments  to  its  pages. —  Western 
Lancet. 

Among  the  numerous  works  upon  Surgerv publish- 
ed of  late  years,  we  know  of  none  we  value  more  highly 
than  the  one  before  us.  It  is,  perhaps,  the  very  best 
we  have  for  a  text-book  and  for  ordinary  reference, 
being  concise  and  eminently  practical. — Southern  Med. 
and  Surg  Journal. 


OPERATIYE  SURGERY; 

BASED  ON  NORMAL  AND  PATPIOLOGIOAL  ANATOMY. 
BY  J.  F.  MALaAIGNE. 

TRANSLATED  FROM  THE  FRENCH,  BY  FREDERIC  BRITTAN,  M.  D.,  &c. 

ILLUSTRATED  BY  WOOD-ENGRAVINGS, 
FROM   DESIGNS  BY  DR.  WESTMACOTT. 

In  one  neat  octavo  volume,  of  564  pages,  extra 
cloth,  $2  25. 

We  have  long  been  accustomed  to  refer  to  it  as  one 
of  the  most  valuable  textbooks  in  our  library.  — 
Buffalo  Med.  and  Surg.  Journal. 

Certainly  one  of  the  best  books  published  on  opera- 
tive surgery. — Edinburgh  Medical  Journal. 

To  express  in  a  few  words  our  opinion  of  Malgaigne's 
work,  we  unhesitatingly  pronounce  it  the  very  best 
guide  in  surgical  operations  that  has  come  before  the 
profession  in  any  language. — Charleston  Medical  and 
Surgical  Journal.  Cheiloplasly  of  the  Lower  Lip. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


67 


New  and  much  Improved  Edition — (Just  Issued.) 

In  one 

very  handsome 

royal  12mo.  volume, 

of  360  pages, 

with  181  Illustrations; 

leather,  $1  50 ; 

extra  cloth,  $1  40. 


Opening  Abscess. 


ON  BANDAGING, 

AND    OTHER   OPERATIONS    OF    MINOR    SURGERY. 
BY  F.   W.   SARGENT,  M.  D., 

One  of  the  Surgeons  to  Wills's  Hospital,  &c. 
NEW   EDITION,    REVISED   AND    ENLARGED. 

This  very  useful  little  work  has  long  been  a  favorite  with  practition- 
ers and  students.  The  recent  call  for  a  new  edition  lias  induced  its 
author  to  make  numerous  important  additions.  A  slii;ht  alteration 
in  the  size  of  the  page  has  enabled  liira  to  introduce  the  new  matter, 
to  the  extent  of  some  fifty  pages  of  the  former  edition,  at  the  same 
time  that  his  volume  is  rendered  still  more  compact  than  its  less  com- 
prehensive predecessors.  A  double  gain  is  thus  effected,  which,  in  a 
vade-mecum  of  this  kind,  is  a  material  improvement. — A9n.  Medical 
Journal. 

Sargent's  Minor  Surgery  has  always  been  popular,  and  deservedly 
so.  It  furnishes  that  knowledge  of  the  most  frequently  requisite  per- 
formances of  surgical  art  which  cannot  be  entirely  understood  by  at- 
tending clinical  lectures.  The  art  of  bandaging,  which  is  regularly 
taught  in  Europe,  is  very  frequently  overlooked  by  teachers  in  this 
country;  the  student  and  junior  practitioner,  therefore,  may  often  re- 
quire that  knowledge  which  this  little  volume  so  tersely  and  happily 
supplies.  It  is  neatly  printed  and  copiously  illustrated  by  the  enter- 
prising publishers,  and  should  be  possessed  by  all  who  desire  to  be 
thoroughly  conversant  with  the  details  of  this  branch  of  our  art. — 
Charleston  Med.  Joitrn.  and  Review. 

The  author  has  selected,  arranged,  and  elucidated  the  subject-matter 
of  his  work  in  a  masterly  manner.  Here  the  student  will  find  nothing 
but  what  is  essential  he  should  know  well  and  never  forget — the  alpha- 
bet of  a  surgical  education.  For  practical  utility  and  comprehensive 
terseness  of  language,  this  volume  has  already  earned  itself  a  reputation;  and  it  is  almost  a  work  of  super- 
erogation, upon  our  part,  earnestly  to  recommend  it  to  those  for  whom  it  is  designed — the  younger  surgeon 
and  student. — Louisville  Review,  Nov.  1856. 

We  have  never  examined  a  work  which  has  better  fulfilled  its  mission.  Dr.  S.  has  given  in  a  portable  and 
neat  volume  an  admirably  illustrated  summary  of  theory  and  practice,  in  relation  to  implements,  bandages, 
fractures,  apparatus,  dislocations,  and  other  cognate  subjects  appertaining  to  the  domain  of  Minor  Surgery. — 
N.  O.  Med.  and  Surg.  Journal. 


Foicr-tailed  Bandage/or 
the  Head. 


MINOR  SURGERY; 

OR,    HINTS   ON    THE    EVERY-DAY    DUTIES   OF   THE   SURGEON. 
BY  HENRY  H.  SMITH,  M.  D., 

Professor  of  Surgery  in  the  University  of  Pennsylvania,  &c. 

THIRD    EDITION,   "WITH    NUMEROUS    ADDITIONS. 


ILLUSTRATED  BY 


In  one  large  royal  12mo.  volume,  of  over  450  pages,  leather,  $2  25 ;  extra  cloth,  $2  00. 


No  young  practitioner  should  be  without  this  little 
volume;  and  we  venture  to  assert,  that  it  may  be 
consulted  by  the  senior  members  of  the  profession 


with  more  real  benefit,  than  the  more  voluminous 
works. —  Western  Lancet. 


6S 


BLANCHARD    AND    LEA'S 


A  NEW  WOKK  ON  THE  TJKINARY  OKGANS— Now  Ready  (1858). 

DISEASES  OE  THE~URINAEY  ORGANS: 

A  COMPENDIUM  OF  THEIR  DIAGNOSIS,  PATHOLOGY,  AND  TREATMENT. 

Bv  WILLIAM  WALLACE  MORLAND,  M.D,, 

Fellow  of  the  Massachusetts  Medical  Society,  &c. 

WITH   ILLUSTRATIONS. 

hi  one  large  and  handsome  octavo  volume^  of  about  600  pp.^ 
extra  cloth.     Price  §3  50. 

This  volume,  it  is  hoped,  will  supply  the  want  of  a  work 
which  within  convenient  compass  should  present  ihe  whole 
subject  of  the  disease*  to  which  all  ihe  urinary  organs  are 
liable,  with  their  treatment,  both  medical  and  surgical.  The 
aim  of  the  author  has  bien  throughout  to  present  the  results 
of  the  most  recent  investigations  in  a  clear  and  succinct  man 
ner,  omitting  nothing  of  practical  importance  without  at  the 
same  time  embarrassing  the  student  with  unnecessary  specu- 
lations. Various  elaborate  and  important  works  have  recent- 
ly appeared  on  different  departments  of  the  subject,  but  none, 
it  is  believed,  which  thoroughly  covers  the  whole  ground  in 

^  ,    ^„  ,     ■ ,  ^^    ,  ,    ,  the  manner  which  Dr.  Morlaud  has  attempted. 

Tube  filled  with  Oil-globules  "^ 

{Fatty  Degeneration  of  Kidney). 

This  work  is  one  of  much  merit,  worthy  of  the  care- 
ful perusal  of  every  physician,  and  deservinj;  of  a 
place  in  his  library,  as  a  book  of  reference.  We  are 
in  want  of  just  such  books  as  this  work  of  Dr.  Mor- 
land.  We  cannot  dismiss  Dr.  M.'s  work  without  the 
declaration  that  it  is  a  good  book,  for  which  he  merits, 
and  we  hope  he  will  receive,  the  substantial  thanks  of 
the  profession. — Med.  and  Surg.  Reporter,  Nov.  5, 1858. 


The  composition  of  these  essays  necessitated  a  care- 
ful examination  of  contemporary  literature,  and  in 
the  subsequent  embodiment  of  them  in  the  present 
systematic  volume,  all  that  has  since  transpired  has 
been  conscientiou.sly  collected  and  well  digested,  bring- 
ing the  work  up  to  the  latest  advances  of  surgical 
science. — NashviUe  Monthly  Record,  Nov.  1858. 


Ne-w  and  Enlarged  Edition — (Just  Issued.) 
THE   PRINCIPLES   AND   PRACTICE   OF 

OPHTHALMIC  MEDICINE  AND  SUPiGERY. 


BY  T.  WHARTON  JONES,  F.  R.  S., 

Professor  of  Ophthalmic  ^Medicine  and  Surgery  in 

University  College,  London. 

"With  110  Illustrations. 

§£tonb  ^m^ritait  ©bition, 
WITH  ADDITIONS, 

FROM  THE  SECOND    AND    REVISED    ENGLISH 
EDITION. 

In  one  large  and  handsome  royal  \2mo.  vol., 
extra  cloth,  of  500  pagts,  $1  50. 

This  favorite  manual  has  received  from 
the  author  a  very  thorough  revision,  bringing 
it  fully  up  to  the  present  state  of  the  sub- 
ject. His  very  extensive  additions,  and  those 
of  the  editor,  have,  however,  been  accom- 
modated by  an  increase  in  the  size  of  the 
page,  without  enlarging  the  bulk  of  the  vo- 
lume, and  the  work  has  accordingly  been  re- 
tained at  its  former  very  moderate  price. 

We  have  always  regarded  Mr.  Jones's  Ophthalmic 
Medicine  and  Surgery  as  incomparably  the  very  best 
manual  ever  published,  in  the  English  language,  upon 
the  subjects  of  which  it  treats.  The  second  edition  ' 
appears  under  many  advantages  over  the  first;  and 
we  may  safely  assert  of  it,  that  we  know  of  no  other 
work  on  the  eye  we  can  so  confidently  reex)mmend  to 
the  student  for  study,  or  to  the  practitioner  for  prac- , 
tice. — Montreal  Med.  Chronicle.  June,  1856.  | 


Granular  Conjunctiva^  with  Pannus. 

This  popular  work  on  Diseases  of  the  Eye  is  a  stand- 
ard authority  both  in  England  and  America.  It  ably 
discusses  the  subject  of  Ophthalmic  Pathology  and 
Therapeutics,  is  cheaper  than  the  larger  works  upon 
these  topics,  and  we  commend  it  to  our  readers  as  a 
most  valuable  guide  in  the  successful  management  of 
this  troublesome  clasa  of  diseases. — Kasliville  Journal 
of  Medicine.  Sept.  1856. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


69 


New  and  Enlarged  Edition— (Recently  Issued.) 


Introduction  of  the  Catheter. 

A   PRACTICAL   TREATISE 

ON  THE 

DISEASES,  INJURIES,  AND   MALFORMATIONS 

OF  THE 

URINARY  BLADDER,  THE  PROSTATE  GLAND,  AND  THE  URETHRA. 
BY  S.  D.  GROSS,  M.  D., 

Professor  of  Surgery  in  the  Jefferson  Medical  College  of  Philadelphia. 
SECOND     EDITION,     REVISED     AND     MUCH    ENLABGED. 

SStitlj  one  IjituirKb  anb  ng^tg-foar  Illustrations. 

In  one  large  and  very  handsome  octavo  volume,  of  over  nine  hundred  pages,  extra  cloth,  $4  75  ; 
leather,  raised  bands,  $5  25. 


Whoever  will  peruse  the  vast  amount  of  valuable 
practical  information  it  contain?,  and  which  we  have 
been  unable  even  to  notice,  will,  we  think,  agree  with 
us.  that  there  is  no  work  in  the  English  language 
which  can  make  any  just  pretensions  to  be  its  equal. 
— iV.  Y.  Journal  of  Medicine. 

On  the  appearance  of  the  first  edition  of  this  work, 
the  leading  English  medical  review  predicted  that  it 
■would  have  a  "  permanent  place  in  the  literature  of 
surgery  worthy  to  rank  with  the  best  works  of  the 
present  age."  This  prediction  has  been  amply  fulfilled. 
Dr.  Gross's  treatise  has  been  found  to  supply  complete- 
ly the  want  which  has  been  felt  ever  since  the  eleva- 
tion of  surgery  to  the  rank  of  science,  of  a  good  prac- 
tical treatise  on  the  diseases  of  the  bladder  and  its 
accessory  organs.  Philosophical  in  its  design,  me- 
thodical in  its  arrangements,  ample  and  sound  in  its 


practical  details,  it  may  in  truth  be  said  to  leave 
scarcely  anything  to  be  desired  on  so  important  a  sub- 
ject, and  with  the  additions  and  modifications  result- 
ing from  future  discoveries  and  improvements,  it  will 
probably  remain  one  of  the  most  valuable  works  on 
this  subject  so  long  as  the  science  of  medicine  shall 
exist. — Boston  Med.  and  Surg.  Journal. 

A  volume  replete  with  truths  and  principles  of  the 
utmost  value  in  the  investigation  of  these  diseases. — 
American  Medical  Journal. 

Dr.  Gross  has  brought  all  his  learning,  experience, 
tact,  and  judgment  to  the  task,  and  has  produced  a 
work  worthy  of  his  high  reputation.  We  feel  per- 
fectly safe  in  recommending  it  to  our  readers  as  a  mo- 
nograph unequalled  in  interest  and  practical  value 
by  any  other  on  the  subject  in  our  language. — The 
Western  Journal  of  Medicine  and  Surgery. 


INSTITUTES  AND  PRACTICE  OF  SURGERY; 

Being  Outlines  of  a  Course  of  Lectures  by  William  Gibson,  M.  D.,  late  Professor  of  Surgery 
in  the  University  of  Pennsylvania.  Eighth  edition,  improved  and  altered.  With  thirty-ibur 
Plates.  In  two  handsome  octavo  volumes,  containing  about  one  thousand  pages.  Leather, 
raised  bands,  $6  50. 


70 


BLANCHARD  AND  LEA'S 


New  and  Enlarged  Edition — (Just  Issued.) 


A  PRACTICAL  TREATISE 


DISEASES  OF  THE  TESTIS, 

AND  OF  THE 

SPERMATIC  CORD  AND  SCROTUM. 

BY  T.  B.  CURLING,  F.R.S., 

Surgeon  to  the  London  Hospital,  &c. 

SECOND  AMERICAN, 

FROM  THE 

Second  Revised  and  Enlarged  London  Edition. 

Watlj  nnmttau^  lUastrations. 

In  one  very  handsome  octavo  volume,  of  over 
AQO  pages,  extra  cloth,  $2  00. 


Chimney-Sweeper''s  Canter. 


To  make  room  for  additional  matter,  the  anatomi- 
cal introduction  was  omitted  in  the  new  London  edi- 
tion, but  we  are  glad  to  notice  that  the  American 
publishers  retain  it.  It  is  by  far  the  best  anatomy  of 
the  testis  we  possess,  and  should  by  all  means  accom- 
pany the  treatise,  giving  it,  as  it  does,  a  completeness 
of  detail  which  satisfies  the  want  of  the  practitioner. 
The  reputation  of  the  work  has  been  so  long  and 
thoroughly  established  that  the  labor  of  the  critic 
may  be  confined  to  the  simple  announcement  of  its 
republication.  Many  who,  since  the  exhaustion  of 
the  previous  edition  have  been  unable  to  procure  it. 
will  doubtless  profit  by  this  hint.  We  need  only  add 
that  it  is  the  most  complete  scientific  and  practical 
account  of  diseases  of  the  testis  in  the  language. — 
Buffalo  Med.  Journal,  Sept.  1856. 


We  have  taken  considerable  pains  to  compare  the 
present  with  the  previous  edition,  and  take  pleasure 
in  stating  as  the  result  of  our  investigations  that  it 
is  in  every  way  superior  to  it.  In  style  and  precision 
of  language  there  is  a  marked  improvement,  a  large 
amount  of  new  and  important  matter  has  been  intro- 
duced by  the  author,  while  his  increased  experience 
has  enabled  him  to  speak  positively  on  many  ques- 
tions in  which  his  opinions  were  indecisively  or  difi'er- 
ently  given  in  the  first  edition.  As  it  now  stands,  we 
can  unhesitatingly  speak  of  it  as  the  first  work  upon 
the  subjects  it  treats  of  in  our  language,  one  worthy 
in  all  respects  of  the  confidence  and  approbation  of 
the  profession.— 3/ed.  Examiner,  Sept.  1856. 


A    PRACTICAL    TREATISE 


FOEEIGN  BODIES 


/  BY  S.  D.  GROSS,  M.  D., 

Professor  of  Surgery  in  Jefferson  Medical  College,  Philadelphia. 

Mxi\  lllastrations. 

In  one  handsome  octavo  volume,  extra  cloth,  of  nearly 
bOO  ])ages  J  price  $2  75. 

A  very  elaborate  work.  It  is  a  complete  summary  of  the 
whole  subject,  and  will  be  a  useful  book  of  reference.— .Bniis/t 
and  Foreign  Medico- Chirurg.  Review. 

A  highly  valuable  book  of  reference  on  a  most  important  sub- 
ject in  the  practice  of  medicine.  We  conclude  by  recommend- 
ing it  to  our  readers,  fully  persuaded  that  its  perusal  will  afford 
them  much  practical  information  well  conveyed,  evidently  de- 
rived from  considerable  experience  and  deduced  from  an  ample 
collection  of  iejiis.— Dublin  Quarterly  Journal. 


Unusual  Co^trse  of  the  Innominata. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


71 


PRACTICAL  OBSERVATIONS  ON  AURAL  SURGERY, 

AND  THE  NATURE  AND  TREATMENT  OF 

DISEASES   OE   THE  E^R. 

IM'iib  llhistrnlious. 
BY  WILLIAM  R.  WILDE, 

Surgeon  to  St.  Mark's  Ophthalmic  Hospital,  &c. 
In  one  very  liandsomc  octavo  volume,  of  about  Jive  hundred  pages,  extra  cloth.  S2  80. 


Instrument  for  removing  Aural  Polypus. 

Preparing  for  early  publication. 

A  TREATISE  ON  FRACTURES  AND  DISLOCATIONS. 

BY   FRANK   H.    HAMILTON,    M.D., 
Professor  of  Surgery  in  Buffalo  Medical  College. 

In  one  handsome  octavo  volume,  toith  numerous  Illustrations. 


The  numerous  improvements  which  this  important  branch  of  surgery  has  received  from  the 
skill  and  ingenuity  of  American  surgeons,  renders  particularly  appropriate  and  valuable  a  com- 
plete and  systematic  original  work  on  the  subject.  The  esf^ays  which  Professor  Hamilton  has 
published  on  kindred  topics  are  already  widely  and  favorably  known,  and  give  earnest  that  his 
forthcoming  work  will  prove  indispensable,  both  as  a  text-book  for  the  student,  and  as  a  guide 
for  the  practitioner. 

A  TREATISE  ON 

DISLOCATION'S  km  FRACTURES  OF  THE  JOINTS. 

By  Sir  Astley  Cooper,  Bart.,  F.  R.  S.,  &c.  A  new  edition,  much  enlarged.  Edited  by  Brans- 
BY  B  Cooper,  F  R  S.  With  additional  observations  by  Prof.  John  C.  Warren.  In  one 
handsome  octavo  volume  of  500  pages;  with  132  Illustrations,  extra  cloth,  $3  25. 


LECTURES  ON  THE  PRINCIPLES  AND  PRACTICE  OF  SURGERY. 

By  Bransby  B.  Cooper,  F.  R.  S.,  Senior  Surgeon  to  Guy's  Hospital,  &c.     In  one  large 
octavo  volume,  of  seven  hundred  and  fifty  pages,  extra  cloth,  $3  00. 

COOPER  ON  THE  STRUCTURE  AND  DISEASES  I  COOPER  ON  THE  ANATOMY  AND  DISEASES  OF 
OF  THE  TESTIS.  AND  ON  THE  THYMUS!  THE  BREAST,  with  Twenty-five  Miscellaneous  and 
GLAND.  One  vol.,  imperial  Svo.,  with  177  figures  Surgical  Papers.  One  large  vol.,  imperial  Svo.,  with 
on  29  plates,  extra  cloth,  $2  00.  I      252  figures  on  36  plates,  extra  cloth,  $2  50. 


STANLEY'S    TREATISE   ON  DISEASES   OF   THE  I  BRODIE'S  CLINICAL  LECTURES  ON   SURGERY. 
BONES.    In  one  vol.  Svo.,  extra  cloth,  28e  pp.,  $1  50.  |      One  vol.  Svo.,  cloth,  350  pp.,  $1  25. 


THE  LAWS  OF  HEALTH  IN  RELATION  TO  MIND  1 
AND  BODY.     A  Series  of  Letter?  from  an  old  Prac- 
titioner to  a  Patient.    By  Lionel  J  ohm  Beale,  M.  R. 


C.  S.,  &c.    In  one  handsome  volume,  royal  12mo., 
extra  cloth,  SO  cents. 


72 


BLANCHARD  AND  LEA'S 


Lately  Published. 

la  one  large      f 

and  closely  printed 

octavo  volume, 

of  over 

1000  pages, 

beautifu  II  y 

illustrated  with 

two  plates 

and 

Cysticerciis  in  Anterior  Chamber.  1&"  WOOd-CUtS. 

Strongly  bound  in  leather,  with  raised  bands,  $6  25. 

Head  and  Neck  of  Cysticercus, 
magnified. 

A  PRACTICAL  TREATISE  ON 

DISEASES   OF   THE   EYE. 

BY  WILLIAM  MACKENZIE,  M.  D., 

Surgeon  Oculist  in  Scotland  in  Ordinary  to  her  Majesty,  &c. 
TO  WHICH  IS  PEEFIXED, 

AN   ANATOMICAL   INTRODUCTION, 
BY  T.  WHARTON  JONES,  F.R.S.,  &c. 

Jrom  i\z  Joutt^  Hetris^b  amb  inlargtir  IToniron  ®bition. 
With  Notes  and  Additions,  bit  ADDINELL  HEWSON,  M.  D., 

One  of  the  Surgeons  to  Wills's  Hospital,  &c. 


Operation  for  Strabismus. 


The  treatise  of  Dr.  Mackenzie  indisputably  holds  the 
first  place,  and  forms,  in  respect  of  loarninp:  and  re- 
search, an  Encyclopfedia  unetiualled  in  extent  by  any 
other  work  of  the  kind,  either  English  or  foreign. — 
Dixon  mi  Diseases  of  the  Eye. 


Few  modern  hooks  on  any  department  of  medicine 
or  sm'gery  have  met  with  such  extended  circulation, 
or  have  procured  for  their  authors  a  like  amount  of 
European  celebrity.  The  immense  research  which  it 
displayed,  the  thorough  acquaintance  with  the  subject, 
practically  as  well  as  theoretically,  and  the  able  man- 
ner in  which  the  author's  stores  of  learning  and  expe- 
rience were  rendered  available  for  general  use,  at  once 
procured  for  the  first  edition,  as  well  on  the  continent 
as  in  this  country,  that  high  position  as  a  standard 
work  which  each  successive  edition  has  more  firmly 
established,  in  spite  of  the  attractions  of  several  rivals 
of  no  mean  ability.  This,  the  fourth  edition,  has  heen 
in  a  great  measure  rewritten  ;  new  matter,  to  the  ex- 
tent of  one  hundred  and  fifty  pages,  has  been  added, 
and  in  several  instances  formerly  expressed  opinions 
have  been  modified  in  accordance  with  the  advances 
in  the  science  which  have  been  made  of  late  years. 
Nothing  worthy  of  repetition  upon  any  branch  of  the 
subject  appears  to  have  escaped  the  author's  notice. 
We  consider  it  the  duty  of  every  one  who  has  the  love 
of  his  profession  and  the  welfare  of  his  patient  at  heart, 
to  make  himself  familiar  with  this  the  most  complete 
work  in  the  English  language  upon  the  diseases  of  the 
eye. — Med.  Times  and  Gazette. 

The  fourth  edition  of  this  standard  work  will  no 
doubt  he  as  fully  appreciated  as  the  three  former  edi- 
tions. It  is  unnecessary  to  say  a  word  in  its  praise, 
for  the  verdict  has  already  been  passed  upon  it  by  the 
most  competent  judges,  and  "Mackenzie  on  the  Eye" 
has  justly  obtained  a  reputation  which  it  is  no  figure 
of  speech  to  call  world-wide. — British  and  Foreign 
Medico-Chirurgical  Review. 

This  new  edition  of  Dr.  Mackenzie's  celebrated  trear 
tise  on  diseases  of  the  eye,  is  truly  a  miracle  of  in- 
dustry and  learning.  We  need  scarcely  say  that  he 
has  entirely  exhausted  the  subject  of  his  specialty. — 
Dublin  Quarterly  Journal. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


73 


A  TREATISE  ON  DISEASES  OF  THE  EYE. 

BY  W.   LAWRENCE,   F.  E.  S,, 

Surgeon  to  St.  Bartholomew's  Hospital,  &c. 

A  NEW  Edition, 

EDITED,    WITH    NUMEROUS    ADDITIONS, 

AND 

STtoo  Ijuubrcb  Hnb  fortg-tljree  llUxstrations, 
BY   ISAAC   HAYS,    M.  D., 

Surgeon  to  VVills's  Hospital,  &c. 

In  one  large  and  handsome  octavo  volume,  of  950  pages,  leather,  raised  bands,  $5  00. 

This  work  is  so  universally  recog-nized  as  the  standard  authority  on  the  subject,  that  the  pub- 
lishers in  presenting- this  new  edition  have  only  to  remark  that  in  its  preparation  the  editor  has 
carefully  revised  every  portion,  introducing  additions  and  illustrations  wherever  the  advance  of 
science  has  rendered  them  necessary  or  desirable,  constituting  it  a  complete  and  thorough  expo- 
nent of  the  most  advanced  state  of  the  subject. 


A  NEW  TEXT-BOOK  OX  INSANITY— Now  Ready  (1858). 


A  MANUAL  OF  PSYCHOLOGICAL  MEDICINE; 

CONTAINING 

THE  HISTORY.  NOSOLOGY,  DESCRIPTION.  STATISTICS.  DIAGNOSIS.  PATHOLOGY.  AND 

TREATMENT  OF 

INSANITY. 

Br  J.  C.  BUCKNILL,  M.  D., 

Medical  Superintendent  of  the  JDevon  County  Lunatic  Asylum, 

AND  DANIEL  H.  TUKE,  M.D., 

Visiting  Medical  Officer  to  the  York  Retreat. 

WITH   A    PLATE. 

In  one  very  neat  octavo  volume  of  536  pages  ;  extra  cloth,  f  3. 

The  increase  of  mental  disease  in  its  various  forms,  and  the  difficult  questions  to  which  it  is 
constantly  giving  rise,  render  the  subject  one  of  daily  enhanced  interest,  requiring  on  the  part  of 
the  physician  a  constantly  greater  familiarity  with  this,  the  most  perplexing  branch  of  his  pro- 
fession. At  the  same  time  there  has  been  for  some  years  no  work  accessible  in  this  country, 
presenting  the  results  of  recent  investigations  in  the  Diagnosis  and  Prognosis  of  insanity,  and 
the  greatly  improved  methods  of  treatment  which  have  done  so  much  in  alleviating  the  condition 
or  restoring  the  health  of  the  insane.  To  fill  this  vacancy  the  publishers  present  this  volume, 
assured  that  the  distinguished  reputation  and  experience  of  the  authors  will  entitle  it  at  once  to 
the  Confidence  of  both  student  and  practitioner.  Its  scope  may  be  gathered  from  the  declaration 
of  the  authors  that  "their  aim  has  been  to  supply  a  text-book  which  may  serve  as  a  guide  in  the 
acqui.-ition  of  such  knowledge,  sulTiciently  elementary  to  be  adapted  to  the  wants  of  the  student, 
and  sufficiently  modern  in  its  views  and  explicit  in  its  teaching  to  suffice  for  the  demands  of  the 
practitioner." 


Every  physician  ought  to  have  some  work  on  In- 
sanity, and,  as  most  can  afford  to  have  hut  one,  we 
would  recommend  this  unreservedly  as  the  hest.  It 
is  sufficiently  full,  it  is  clear  in  its  statements  and  de- 
scriptions, and  very  discriminating  in  its  practical 
views.  .  .  .  We  have  seldom  met  with  a  collection  of 
such  judicious  views  of  the  treatment  of  disease  as 
are  in  this  chapter  presented  of  the  treatment  of  in- 
sanity, and  we  would  commend  them  to  the  careful 
examination  of  the  profession,  not  only  from  their 
value  in  their  .special  hearing  on  this  disease,  but  also 
on  account  of  their  development  of  the  true  princi- 
ples of  the  treatment  of  disease.s  generally. — Am.  Med. 
Journal,  Oct.  1858. 

It  will,  we  suppose,  he  generally  gratifyinjr  to  the 
members  of  the  specialty,  that  at  a  time  when  in- 
creased attention  is  being  paid  to  mental  disease  by 
the  profession,  a  representative  treatise  has  been  un- 
dertaken by  gentlemen  so  well  and  so  favorably  knowr) 
as  Drs.  Bucknill  and  Tuke.  Their  scientific  and  lite- 
rary ability,  with  their  large  practical  acquaintance 
with  their  subject,  should  indeed  eminently  tit  them 
for  the  task;  and.  taken  as  a  whole,  the  result  of  their 
labors  will  not  fail  to  answer  a  just  anticipation.  We 
do  not  know  where  anything  can  be  found  in  the  lite- 
rature of  the  specialty  to  compare  with  these  essays, 


in  complete  and  logical  treatment,  and  the  clear,  prac- 
tical manner  in  which  their  subjects  are  discussed. 
They  will  be  cited  as  authority  wherever  the  language 
is  used,  and  will,  no  doubt,  be  extensively  translated. 
— Am.  Journ.  of  Insanity,  Oct.  1858. 

We  know  of  no  one  book  which  so  fully  embraces 
everything  connected  with  the  insane.  Altogether, 
we  can  confidently  recommend  the  work  to  our  read- 
ers; we  believe  they  will  find  it  one  which  deserves 
to  be  valued  even  beyond  any  praise  which  we  have 
deemed  it  our  duty  to  accord  to  a  volume  of  both  great 
medical  and  great  moral  merit. — Dublin  Quarterly 
Jom-nal,  Aug.  1858. 

In  conclusion,  we  can  say,  in  all  sincerity,  that  sel- 
dom have  the  expectations  raised  by  the  language  of 
the  Preface  been  so  fully  realized  in  the  execution  of 
the  work  as  in  the  volume  of  Drs  Bucknill  and  Tuke. 
Its  publication  removes  all  excuse  that  may,  hitherto, 
have  been  alleged  by  students  and  practitioners  of 
medicine  for  neglect  of  the  subject  owing  to  the  want 
of  a  work  of  insanity  for  ready  reference — one  which, 
like  the  present,  contains  sound  principles,  enforced 
and  illustrated  by  a  series  of  pertinent  and  well- 
digested  facts,  evidently  accumulated  by  long  person- 
al experience  and  much  reading — North  American 
Medico-Chirurgical  Review,  Sept.  1858. 


74 


BLANCHARD  &  LEA'S 


New  and  Enlarged  Edition. 

MEDICAL  JURISPRUDENCE. 

BY  ALFRED  S.  TAYLOR,  M.  D.,  F.  R.  S., 

Lecturer  on  Medical  Jurisprudence  and  Chemistry  in  Guy's  Hospital,  &c. 
Fourtli  American,  from  tlie   Fifth  and  Improved  liOndon  Kdltion. 

WITH  NOTES  AND  REFERENCES  TO  AMERICAN  DECISIONS, 

BY  EDWARD  HARTSHORNE,  M.  D. 

In  one  large  octavo  volume,  of  seven  hundred  closely  printed  pages,  leather,  $3  00. 

This  standard  work  has  lately  received  a  very  thorough  revision  at  the  hands  of  tho  author, 
who  has  introduced  whatever  was  necessary  to  render  it  complete  and  satisfactory  in  carrying 
out  the  objects  in  view.  The  editor  has  likewise  used  every  exertion  to  make  it  equally  tho- 
rough with  regard  to  all  matters  relating  to  the  practice  of  this  country.  In  doing  this,  he  has 
carefully  examined  all  that  has  appeared  on  the  subject  since  the  publication  of  the  last  edition,  and 
has  incorporated  all  the  new  information  thus  presented.  The  work  has  thus  been  considerably 
increased  in  size,  notwithstanding  which,  it  has  been  kept  at  its  former  very  moderate  price, 
and  in  every  respect  it  will  be  found  worthy  of  a  continuance  of  the  remarkable  favor  which 
has  carried  it  through  so  many  editions  on  both  sides  of  the  Atlantic. 


We  hazard  little  in  affirming  our  belief  that  Taylor's 
Medical  Jurisprudence  is  the  best  manual  on  its  sub- 
ject in  any  language.  It  has  so  long  occupied  the 
first  rank  among  our  most  popular  text-books,  and  is 
so  favorably  known  to  our  readers  of  every  kind,  legal, 
medical,  and  general,  that  the  mere  announcement 
of  a  new  edition  is  an  all-sufficient  recommendation. 
The  previous  efforts  of  its  author  and  editor  affijrd 
ample  guaranty  of  continued  improvements  in  each 
new  issue  of  their  work ;  and  we  need  only  to  make  a 
cursory  examination  of  the  volume  before  us  to  be 
satisfied  that  the  additions  and  alterations  are  both 
numerous  and  important,  and  such  as  fully  to  sustain 
the  previous  reputation  of  the  manual,  and  that  of 
its  indefatigable  author  — Med.  Examiner. 

The  work  of  Dr.  Taylor  is  now  recognized  by  the  pro- 
fession generally  as  ranking  among  the  best  element- 
ary treatises  on  medical  jurisprudence  in  the  English 
language.  We  know  of  none  in  which  the  subject  may 
be  more  profitably  studied;  no  one  better  adapted  for 
casual  reference  with  the  view  to  refresh  the  memory 
in  respect  to  any  especial  question  within  the  general 
scope  of  forensic  medicine.  The  author  has,  with 
admirable  judgment,  selected  from  the  immense  mass 
of  materials  at  his  disposal  those  best  calculated  to  re- 


present the  actual  condition  of  medico-legal  know- 
ledge, and  has  arranged  these  in  a  manner  calculated 
to  present  the  requisite  information  with  that  clear- 
ness and  precision  so  essential  in  an  elementary  trea- 
tise.— Am.  Journ.  Med.  Sciences. 

It  is  at  once  comprehensive  and  eminently  practical, 
and  by  universal  consent  stands  at  the  head  of  Ame- 
rican and  British  legal  medicine.  It  should  be  in  the 
possession  of  every  physician,  as  the  subject  is  one  of 
great  and  increasing  importance  to  the  public  as  well 
as  to  the  profession. — .S'^  Louis  Med.  and  Surg.  Journal. 

This  work  of  Dr.  Taylor's  is  generally  acknowledged 
to  be  one  of  the  ablest  extant  on  the  subject  of  medical 
jurisprudence.  It  is  certainly  one  of  the  most  attract- 
ive books  that  we  have  met  with ;  supplying  so  much 
both  to  interest  and  instruct,  that  we  do  not  hesitate 
to  affirm  that  after  having  once  commenced  its  peru- 
sal, few  could  be  prevailed  upon  to  desist  before  com- 
pleting it.  In  the  last  London  edition,  all  the  newly 
observed  and  accurately  recorded  facts  have  been  in- 
serted, including  much  that  is  recent  of  Chemical, 
Microscopical,  and  Pathological  research,  besides  pa- 
pers on  numerous  subjects  never  before  published. — 
Charleston  Medical  Journal  and  Review. 


By  the  same  Author— Now  Ready  (June  1859). 

ON  x>oisoisrs, 

IN    RELATION   TO   MEDICAL   JURISPRUDENCE  AND   MEDICINE. 

Second  American,  from  the  Second  and  Revised  English  Edition. 

In  one  large  octavo  volume  of  Ibb  pages,  leather,  $3  50. 

The  length  of  time  which  has  elapsed  since  the  first  appearance  of  this  work  has  wrought  so 
great  a  change  in  the  subject  as  to  require  a  very  thorough  revision  to  adapt  the  volume  to  the 
present  wants  of  the  profession.  The  rapid  advance  of  Chemistry  has  introduced  into  use  many 
new  substances  which  may  become  fatal  through  accident,  carelessness,  or  design — while  at  the 
same  time  it  has  likewise  designated  new  and  more  exact  modes  of  counteraciing  or  detecting 
those  previously  treated  of.  Mr.  Taylor's  position  as  the  leading  medical  jurist  of  England,  has 
during  this  period  conferred  on  him  extraordinary  advantages  in  acquiring  experience  in  all  that 
relates  to  this  department,  nearly  all  cases  of  moment  being  referred  to  him  for  examination,  as 
an  expert  whose  testimony  is  generally  accepted  as  final.  The  results  of  his  labors,  therefore, 
as  gathered  together  in  this  volume,  carefully  weighed  and  sified,  and  presented  in  the  clear  and 
intelligible  style  for  which  he  is  noted,  may  be  received  as  an  acknowledged  authority,  and  as 
a  guide  to  be  followed  with  implicit  confidence. 

In  his  Preface  the  author  says : — 

"  My  space  has  been  limited,  and  I  have  endeavored  to  fill  it  with  materials  which  may  be  of 
profit  to  the  practitioners  of  law  and  medicine,  for  whose  especial  use  this  volume  is  intended. 
Under  this  view  the  plan  of  the  former  edition  has  been  entirely  changed.  Many  chapters  have 
been  struck  out,  and  an  equal  number  of  new  chapters  introduced.  The  requirements  of  a  pe 
riod  dating  no  longer  ago  than  ten  years  are  different  from  those  of  the  present  day,  and  it  is 
the  duty  of  an  author,  so  far  as  it  may  be  in  his  power  and  consistent  with  the  scope  of  his 
labors,  to  fulfil  these  requirements  by  an  entire  remodelling  of  his  subject." 


The  most  elaborate  work  on  the  subject  that  our 
literature  possesses. — British  and  Foreign  Medico-Chi- 
rurgical  Review. 

It  contains  a  vast  body  of  facts,  which  embrace  all 
that  is  important  in  toxicology,  all  that  is  necessary 
to  the  guidance  of  the  medical  jurist,  and  all  that  can 
be  desired  by  the  lawyer. — Medico-Chirurg.  Review. 


One  of  the  most  practical  and  trustworthy  works 
on  Poisons  in  our  language. —  Western  Jaum.  of  Med. 

It  is,  so  far  as  our  knowledge  extends,  incomparably 
the  best  upon  the  subject;  in  the  highest  degree  cre- 
ditable to  the  author,  entirely  trustworthy,  and  indis- 
pensable to  the  student  and  practitioner. — N.  Y.  An- 
nalist. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS. 


75 


A  Series  of  Text-books  on  Physical  Science. 
HANDBOOKS 

OF 

MTURAL  PHILOSOPHY  AND  ASTRONOMY. 

BY  DIONYSIUS  LARDNER,  D.  C.  L., 

Formerly  Professor  of  Natural  Philosophy  and  Astronomy  in  University  College,  London. 


This  valuable  series  is  now  complete,  consisting-  of  three  Courses,  as  follows : — 

FIRST  COURSE. 

51ECHANICS,  RYDROSTATICS,  HYDRAULICS,  PNEUMATICS,  SOUND,  AND  OPTICS. 

In  one  large  royal  \2mo.  volume  of  750  pages,  with  424  illustrations /  $1  75. 
SECOND  COURSE. 

HEAT,  MAGNETISM,  COMMON  ELECTRICITY,  AND  VOLTAIC  ELECTRICITY. 

In  one  royal  12mo,  volume  of  AbO  2:)ages,  with  244  illustrations  j  $1  25. 


THIRD  COURSE. 

ASTRONOMY   AND    METEOROLOGY. 

In  one  very  large  royal  12»io.  volume  of  nearly  800  pages,  with  2>1  pilates  and  over  200  illus- 
trations.    $2. 

These  volumes  can  be  had  either  separately  or  in  uniform  sets,  containing 

About  two  thousand  pages,  and  nearly  one  thousand  Illustrations  on  Steel  and  Wood. 

To  accommodate  those  who  desire  separate  treatises  on  the  leadmg  departments  of  Natural 
Philosophy,  the  First  Course  may  also  be  had  divided  in  three  portions,  as  follows : — 

Part    I.— MECHANICS,  price  70  cents. 

«'     II.— HYDROSTATICS,  HYDRAULICS,  PNEUMATICS,  and  SOUND,  price  60  cts. 

"    III.— OPTICS,  price  70  cents. 

It  will  thus  be  seen  that  this  work  furnishes  either  a  complete  course  of  instruction  on  these 
subjects,  or  separate  treatises  on  all  the  different  branches  of  Physical  Science. 

The  object  of  the  author  has  been  to  prepare  a  work  suited  equally  for  the  collegiate,  acade- 
mical, and  private  st  udent,  who  may  desire  to  acquaint  himself  with  the  present  state  of  science, 
in  its  most  advanced  condition,  without  pursuing  it  through  its  mathematical  consequences  and 
details.  Great  attention  has  been  paid  throughout  the  w^ork  to  elucidating  the  principles  ad- 
vanced by  their  practical  applications  to  the  wants  and  purposes  of  civilized  life,  a  task  to  which 
Dr.  Lardner's  immense  and  varied  knowledge,  and  his  singular  felicity  and  clearness  of  illustra- 
tion render  him  admirably  fitted.  This  peculiarity  of  the  work  recommends  it  especially  as  the 
text-book  for  a  practical  age  and  country  such  as  ours,  as  it  interests  the  student's  mind  by  show- 
ing him  the  utility  of  his  studies,  while  it  directs  his  attention  to  the  further  extension  of  that 
utility  by  the  fulness  of  its  examples.  Its  extensive  adoption  in  many  of  our  most  distinguished 
colleges  and  seminaries  is  sufficient  proof  of  the  skill  with  which  the  author's  intentions  have 
been  carried  out. 


From  Prof.  W.  L.  Brown,  Oakland  College,  Miss. 
I  consider  them  most  admirably  suited  for  the  pur- 
poses designed  by  the  author  —  indeed,  as  the  very 
best  popular  works  on  physical  science  with  which  I 
am  acquainted  The  '-Third  Course,"  on  Astronomy, 
is  especially  valuable;  its  magnificent  engravings 
and  lucid  explanations  make  it  a  most  desirable  text- 
book. 

From  Sev.  J.  6.  Ralston,  JVorristown,  Pa. 
Lardner's  Meteorology  and  Astronomy  is  a  fit  com- 
panion for  his  First  and  Second  Course.  It  is  won- 
derfully minute,  and  yet  not  prolix.  The  principles 
of  Astronomy  are  probably  as  clearly  defined  and 
judiciously  arranged  in  this  book  as  they  can  be.  I 
expect  to  introduce  it  in  my  school. 

From  S.  Schooler,  Esq.,  Hanover  Academy,  Va. 
The  three  volumes  constitute  a  body  of  information 
and  detail  on  nearly  the  whole  range  of  physical  sci- 
ence which  is  not  to  be  found  together  in  any  other 
publication  with  which  I  am  acquainted.   I  hope  that 


these  works  may  be  the  means  of  inducing  many  of 
our  youth  to  devote  themselves  to  the  development 
of  the  Laws  of  Nature,  and  the  application  of  them 
to  industry,  and  that  tliey  may  be  the  vehicle  for  con- 
veying sound  information  and  food  for  thought  to 
every  man  who  aspires  to  be  well  educated. 

From  M.  Conant,  State  Normal  School,  Mass. 
This  is  a  treatise  admirably  adapted  to  its  purpose. 
For  the  accurate  knowledge  it  unfolds,  and  the  very 
popular  dress  it  appears  in,  I  think  I  have  met  with 
nothing  like  it.  I  shall  advise  the  students  of  the 
Normal  School  to  add  this  to  your  edition  of  Lardner's 
Mechanics,  &c. 

From  Prof.  E.  Everett,  New  Orleans. 
I  am  already  acquainted  with  the  merits  of  this 
book,  having  had  occasion  to  consult  it  in  teaching 
the  branches  of  which  it  treats,  and  I  cannot  give  you 
a  stronger  assurance  of  my  high  opinion  of  it  than  the 
simple  fact  that  I  have  selected  it  as  the  text-book  of 
Physics  in  the  course  of  study  which  I  have  just  fixed 
upon  for  a  new  college  to  be  established  here. 


76 


BLANCHARD  AND  LEA'S 


In  one  very  handsome 

oclavo  volume, 

of  nearly  six  hundred  and  fifty  pages, 

with 

over  five  hundred 

beautiful  Illustrations  on  wood, 

and  two  colored  Plates, 

extra  cloth,  $3  50. 


Hart's  Calorimotor 


Structure  of  the  Larynx. 


PRKiCIPLES  OF  PHYSICS  AND  METEOPiOLOGY. 

BY  J.   MULLER, 

Professor  of  Physics  at  the  University  of  Freiburg,  &c. 
Revised,  with  Additions,  by  R.  E.  GRIFFITH,  M.  D. 


In  the  work  before  us,  the  first  thing  which  strikes 
us  is  the  profusion  of  wood-cuts  beyond  what  we 
should  have  imagined  any  publisher  could  furnish  at 
the  price— and  very  good  cuts.  The  matter  of  the 
work  is  sound,  and  ranges  over  the  subjects  well.  The 
manner  is  popular,  and  the  author,  though  a  mathe- 
matician, introduces  only  formulae  to  look  at  now  and 
then,  without  algebraic  processes.  We  strongly  re- 
commend this  work,  particularly  for  the  libraries  of 
schools,  mechanics'  institutes,  and  the  like.  The  pre- 
sent volume  contains  excellent  reading  and  reference 
for  those  who  are  to  have  but  one  book  on  the  subject. 
— AtkencBum. 

The  plan  adopted  by  Muller  is  simple ;  it  reminds 
us  of  the  excellent  and  popular  treatise  published 
many  years  since  by  Dr.  Arnott,  but  it  takes  a  much 
wider  range  of  subjects.    Like  it,  all  the  necessary 


explanations  are  given  in  clear  and  concise  language, 
without  more  than  an  occasional  reference  to  mathe- 
matics; and  the  treatise  is  most  abundantly  illus- 
trated with  well-executed  wood  engravings. 

The  author  has  actually  contrived  to  comprise  in 
about  five  hundred  pages,  including  the  space  occupied 
by  illustrations,  Mechanics,  the  laws  of  Motion.  Acous- 
tics, Light,  Magnetism,  Electricity,  Galvanism,  Electro- 
Magnetism,  Heat,  and  Meteorology. 

Medical  practitioners  and  students,  even  if  they 
have  the  means  to  procure,  have  certainly  not  the 
time  to  study  an  elaborate  treatise  in  every  branch  of 
science;  and  the  question  therefore  is,  simply,  whe- 
ther they  are  to  remain  wholly  ignorant  of  such  sub- 
jects, or  to  make  a  profitable  use  of  the  labors  of  those 
who  have  the  happy  art  of  saying  or  suggesting  much 
in  a  small  space. 


ELEMENTS  OF  NATURAL  PHILOSOPHY; 

BEING  AN  EXPERIMENTAL  INTRODUCTION  TO  THE  PHYSICAL  SCIENCES. 
Illustrated  with  over  three  hundred  wood-cuts.  By  Golding  Bird,  M.  D.,  Assistant  Physician 
to  Guy's  Hospital.  From  the  Third  and  Improved  London  edition.  In  one  handsome  royal 
12mo.  volume,  of  over  400  very  large  pages,  on  small  type,  leather,  f  1  50 ;  extra  cloth,  $1  '25. 

ELEMENTS    OF   PHYSICS  ; 

OR,  NATURAL  PHILOSOPHY,  GENERAL  AND  MEDICAL.  Written  for  universal  use 
in  plain,  or  non-technical  language.  By  Neill  Arnott,  M.  D.  A  new  edition,  revised  and 
corrected  from  the  last  English  edition,  with  Additions,  by  Isaac  Hays,  M.  D.  With  about 
two  hundred  illustrations.    In  one  octavo  volume,  of  nearly  five  hundred  pages,  leather,  $2  50. 

ZOOPHYTES    AND    CORALS. 

By  James  D.  Dana.  In  one  large  imperial  quarto  volume,  extra  cloth,  with  wood-cuts.  (U.  S. 
Exploring  Expedition.)    f  15  00. 

Also,  An  Atlas  to  the  above,  in  one  imperial  folio  volume,  half  bound  in  morocco,  with  sixty- 
one  large  plates,  exquisitely  colored  after  nature,    f  30  00. 


BY  THE  SAME  ATJTHOE. 

THE  STRUCTURE  AND  CLASSIFICATION  OF  ZOOPHYTES, 
volume,  extra  cloth.    $4  50. 


In  one  imperial  quarto 


ASPECTS    OF    NATURE 

IN  DIFFERENT  LANDS  AND  DIFFERENT  CLIMATES.  With  Scientific  Elucidations. 
By  Alexander  Von  Humboldt.  Translated  by  Mrs.  Sabine.  In  one  large  and  handsome 
royal  12mo.  volume,  extra  cloth.     $1  00. 


MEDICAL  AND  SCIENTIFIC   PUBLICATIONS, 


77 


HBRSCHEL'S    ASTRONOMY. 


OUTLINES   OF   ASTRONOMY. 

BY  SIR  JOHN  F.  W.  HERSCHEL,  Bart.,  F.  R.  S.,  &c. 

g.  ncfa  American,  from  tljc  fourtlj  anir  nhm)i  IToivbon  tintioix. 

In  one  handsome  crown  octavo  volume,  with  numerous  plates  and  loood-euts,  extra  cloth,  $1  60; 

or,  half  bound,  leather  backs  and  cloth  sides,  $1  75. 

The  present  work  is  reprinted  from  the  last  London  edition,  which  was  carefully  revised  by 

the  author,  and  in  which  he  embodies  the  latest  investigations  and  discoveries.    It  may  therefore 

be  re°-arded  as  fully  on  a  level  with  the  most  advanced  state  of  the  science,  and  even  better 

adapted  than  its  predecessors,  as  a  full  and  reliable  manual. 

From  Prof.  A.  Casivdl,  Brown  University,  R.  J. 
As  a  work  of  reference  and  study  for  the  more  ad- 
vanced pupils,  who  yet  are  not  prepared  to  avail  them- 
selves of  the  higher  mathematics,  1  know  of  no  work 
to  be  compared  with  it. 


From  Professor  D.  Olmsiead,  Tale  College. 
A  rich  mine  of  all  that  is  most  valuable  in  modern 
Astronomy. 


THE    PRINCIPLES    OF 

ANIMAL  AND  VEGETABLE  PHYSIOLOGY. 

A  POPULAR  TREATISE 

ON   THE 

FUNCTIONS  AND  PHENOMENA 

OF 

ORGANIC    LIFE. 

BY  J.  STEVENSON  BUSHNAN,  M.  D. 

"With  102  Illustrations.  J||)j|  ii^...^  ... 

Hill     '  i^At''''  4v1     I 

In  one  very  neat  royal  12mo.  vohime,  of  234    s||    \vi|  ^ ^i^^ 
pages,  extra  cloth,  90  cents.  %  %    il\jijlW^' 

Spiracle  of  Fly. 


The  Illustrated  Geographical  Encyclopaedia. 

THE  ENCYCLOPJlDll  OF  GEOGRAPHY. 

COMPRISING  A  COMPLETE  DESCRIPTION  OF  THE    EARTH,   PHYSICAL,    STATISTICAL,  CIVIL,  AND 

POLITICAL.      EXHIBITING  ITS  RELATION  TO  THE  HEAVENLY  BODIES,  ITS  PHYSICAL  STRUC- 

TtJRE,  THE    NATURAL    HISTORY   OF    EACH    COUNTRY,    AND    THE  INDUSTRY,   COMMERCE, 

POLITICAL  INSTITUTIONS,  AND  CIVIL  AND  SOCIAL  STATE  OP  ALL  NATIONS. 

BY  HUGH  MURRAY,  F.  R.  S.  E.,  &c. 

Assisted  in  Botany,  by  Professor  HOOKER— Zoology,  &c.,  by  W.  W.  SWAINSON— Astrono- 
my, &c.,  by  Professor  WALLACE— Geology,  &c.,  by  Professor  JAMESON. 

REVISED,    WITH   ADDITIONS, 

BY  THOMAS  G.  BRADFORD. 

In  three  large  octavo  volumes,  containing  about  nineteen  hundred  large  imperial  pages,  and 

ILLUSTRATED  BY  EIGHTY-TWO  SMALL  MAPS. 

And  a  colored  Map  of  the  United  States,  after  Tanner's  ;  together  vf'Ah.  about 

Eleven  Hundred  Wood-cuts,  executed  in  the  best  style. 

In  leather,  gilt,  $5  00;  library  style,  $4  50;  extra  cloth,  $4. 


Skinner's  Complete  Edition  of  Youatt  on  the  Horse. 
A   BOOK   FOR   EVERY    FARMER   AND   COUNTRY   GENTLEMAN. 

THE  HORSE.  By  William  Youatt.  A  new  edition,  with  numerous  Illui=trations.  Toge- 
ther with  a  General  History  of  the  Horse;  a  Dissertation  on  the  American  Trotting  Horse, 
how  Trained  and  Jockeyed;  an  account  of  his  remarkable  performances;  and  an  Essay  on 
the  Ass  and  the  Mule.  By  J.  S.  Skinner,  Assistant  Postmaster-genera),  and  Editor  of  the 
Turf  Register.  In  one  octavo  volume,  of  neai'ly  450  large  pages,  with  numerous  Illustra- 
tions; price,  in  extra  cloth,  f  1  50;  leather,  fl  7-S. 


78 


BLANCHARD  AND  LEA'S 


THE  BOOK  OF  NATUKE 


AN    ELEMENTARY    INTRODUCTION    TO    THE    SCIENCES    OF 


PHYSICS, 

ASTRONOMY, 

CHEMISTRY, 


MINERALOGY, 

GEOLOGY, 

BOTANY, 


ZOOLOGY, 

AND 

PHYSIOLOGY. 


.  BY  FRIEDRICH  SCHOEDLER,  Ph.  D., 

Professor  of  the  Natural  Sciences  at  Worms,  &o.  &c. 
First  American  Edition,  with  a  Glossary  and  other  Additions  and  Improvements,  from  the  Second  English  Edition 

TRANSLATED  FROM  THE  SIXTH  GERMAN  EDITION, 

BY   HENRY   ME  BLOCK,   F.  C.  S.,  &c. 


Profu  sel  y 

illustrated 

with  nearly 

seven  hundred 

beautiful 

engravings 

on  wood. 

In  one  large 
and   handsome 
crown  octavo 

volume, 
of  692  pages, 
extra  cloth ; 
price  fl  80. 


The  Geysers  of  Iceland  (Geology). 

To  accommodate  those  who  desire  to  use  the  separate  portions  of  this  work,  the  publishers 
have  prepared  an  edition  in  parts,  as  follows,  which  may  be  had  singly,  neatly  done  up  in  flexi- 
ble cloth,  at  50  ceats  each. 


Natural  Phllosopliy, 

114  pages,  with  149  illustrations. 
Astrouomy,         64     "         "      51  '• 

Chemistry,         110     «         "      48  " 

Mineralogy  and  Geology, 

104  pages,  with  167  " 

This  volume,  as  its  title  shows,  covers  nearly  all  the 
sciences,  and  embodies  a  vast  amount  of  information 
for  instruction.  No  other  work  that  we  have  seen 
presents  the  reader  with  so  wide  a  range  of  element- 
ary knowledge,  with  so  full  illustrations,  at  so  cheap 
a  rate. — Silliman's  Journal. 

Written  with  remarkable  clearness,  and  scrupu- 
lously correct  in  its  details. — Mining  Journal. 

His  expositions  are  most  lucid.  There  are  few  who 
will  not  follow  him  with  pleasure  as  well  as  with  pro- 
fit through  his  masterly  exposition  of  the  principles 
and  primary  laws  of  science.  It  should  certainly  be 
made  a  class-book  in  schools. —  Critic. 


Botany, 


98  pages,  with  176  illustrations. 


Zoology  and  Pbyslology, 

106  pages,  with  84  " 

Introduction,  Glossary,  Index,  ^c., 


Composed  by  the  same  distinguished  author,  all  the 
departments  have  a  uniformity  of  style  and  illustra- 
tion which  harmoniously  link  the  entire  circle  to- 
gether. The  utility  of  such  a  connected  view  of  the 
physical  sciences,  and  on  such  an  approved  basis,  is 
beyond  price ;  and  places  their  acquisition  within  the 
reach  of  a  vastly  increased  number  of  inquirers.  Not 
only  to  such  is  it  valuable,  but  to  those  who  wish  to 
have  at  hand  the  means  of  refreshing  their  memories 
and  enlarging  their  views  upou  their  favorite  studies. 
Of  such  a  book  we  speak  cordially,  and  would  speak 
more  at  length,  if  space  permitted. — Southern  Metlio- 
dist  Quarterly  Review. 


THE    DOa. 


By  WILLIAM  YOUATT. 

Edited,  with  Additions,  by  E.  J.  LEWIS,  M.  D. 

WITH   NUMEROUS    PLATES    AND    WOOD-GUTS. 

In  one  very  handsome  volume,  crown  octavo,  done  up  in  beautiful  crimson  cloth,  gilt  stamps,  $1  25. 


MEDICAL  AND  SCIENTIFIC  PUBLICATIONS. 


79 


PRINCIPLES   OF   THE 

MECHANICS  OF  MACHINERY  AND  ENGINEERING. 

BY  PROFESSOR  JULIUS  WEISBACH. 

Translated  and  Edited  by  PROFESSOR  GORDON,  or  Glasgow. 

Jtrst  American  ^bition,  iaitlj  ^bititions, 

BY  PROFESSOR  WALTER  R.  JOHNSON. 

In  tivo  very  handsome  octavo  volumes,  of  nearly  900  pages,  with  about  900  superb  Jlhistraiions, 
handsomely  and  strongly  bound  in  extra  cloth,  $6  50. 


Overshot  Water-  Wheel. 


These  volumes  contain  an  immense  amount  of  practical  information  necessary  to  the  ma- 
chinist, architect,  and  civil  engineer ;  the  whole  thoroughly  brought  up  to  the  most  advanced 
state  of  scientific  investigation.  The  following  rapid  summary  of  the  contents  will  show  the 
manner  in  which  the  subjects  are  successively  brought  forward. 

Volume  H. 

Section  I.  Application  of  Mechanics  in  Build- 


Volume  I. 

Sect.  I.  Mathematical  Science  of  Motion. 
Sect.  II.  Mechanics  in  the  Physical  Science  of 

Motion  in  general. 
Sect.  III.  Statics  of  Rigid  Bodies. 
Sect.  IV.  Dynamics  of  Rigid  Bodies. 
Sect.  V.  Statics  of  Fluid  Bodies. 
Sect.  VI.  Dynamics  of  Fluid  Bodies. 


Division  II.  Application  of  Mechanics  to  Ma- 
chinery. 

Section  II.  Of  Moving  Powers  and  their  Ef- 
fects. 


These  subjects,  treated  in  all  their  ramifications  and  practical  applications  to  Machines, 
Water-powers,  Dams,  Bridges,  Water-wheels,  Turbines,  Roofs,  Walls,  Arches,  Windmills, 
Scales,  Steam-boilers,  Water-engines,  &c.  &c.,  present  points  of  primary  importance  to  every 
one  engaged  in  machine-work  of  every  description,  building,  or  engineering ;  while  the  compre- 
hension of  the  whole  is  greatly  facilitated  by  the  profusion  of  clear  and  beautifully  executed 
illustrations  which  are  interspersed  throughout  the  work. 


THE    YOUNG     MILLWRIGHT, 

AND  MILLER'S  GUIDE.  Illustrated  by  twenty-eight  Descriptive  Plates.  By  Oliver  Evans, 
with  Additions  and  Corrections  by  Thomas  P.  Jones.  With  a  Description  of  an  Improved 
Merchant  Flour-mill,  by  C.  and  O.  Evans.  Fourteenth  edition.  In  one  handsome  octavo 
volume,  strongly  bound  in  leather,  $2  50. 


BLANCHARD  AND  LEA'S  PUBLICATIONS. 


New  and  much  Improved  Edition — (Lately  Issued.) 

PHYSICAL  GEOGRAPHY. 

BY  MARY  SOMERVILLE. 

A    NEW    AMERICAN,     FROM     THE     THIRD     AND    REVISED     LONDON     EDITION. 
WITH  NOTES  AND  A  GLOSSARY, 

BY  W.  S.  W.  RUSCHENBERGER,  M.  D.,  U.  S.  Navy. 

In  one  large  royal  llmo.  volume,  of  nearly  600  pages,  extra  cloth,  $1  2b;  half  hound 
in  leather,  $1  36. 

Eulog-y  is  unnecessary  with  regard  to  a  work  like  the  present,  which  has  passed  through 
three  editions  on  each  side  of  the  Atlantic  within  the  space  of  a  few  years.  The  publishers 
therefore  only  consider  it  necessary  to  stale  that  the  last  London  edition  received  a  thorough 
revision  at  the  hands  of  the  author,  who  introduced  whatever  improvements  and  corrections 
the  advance  of  science  rendered  desirable,  and  that  the  present  issue,  in  addition  to  this,  has  had 
a  careful  examination  on  the  part  of  the  editor,  to  adapt  it  more  specially  to  this  country.  Great 
care  has  been  exercised  in  both  the  text  and  the  glossary  to  obtain  the  accuracy  so  essential  to 
a  work  of  this  nature,  and  in  its  present  improved  and  enlarged  state,  with  no  corresponding  in- 
crease of  price,  it  is  confidently  presented  as  in  every  way  worthy  a  continuance  of  the  striking 
favor  with  which  it  has  been  everywhere  received. 


From  Lieutenatjt  Maury,  U.  S.  iV. 

National  Observatory,  Washington. 
I  thank  you  for  the  "  Physical  Geography ;"  it  is 
capital.  I  have  been  reading  it,  and  like  it  so  much 
that  I  have  made  it  a  school-book  for  my  children, 
whom  I  am  teaching.  There  is,  in  my  opinion,  no 
■work  upon  that  interesting  subject  on  which  it  treats — 
Physical  Geography — that  would  make  a  better  text- 
book in  our  schools  and  colleges.  I  hope  it  will  be 
adopted  as  such  generally,  for  you  have  Americanized 
it  and  improved  it  in  other  respects. 


From  Samuel  H.  Taylor,  Esq.,  Philips  Academy, 

Andcnxr,  Mass.,  Feb.  15, 1854. 
We  have  introduced  your  edition  of  Mrs.  Somer- 
ville's  '■  Physical   Geography"  into  our  school,  and 
tind  it  an  admirable  work. 

From  Thomas  Shermin,  High  School,  Boston. 
T  hold  it  in  the  highest  estimation,  and  am  confident 
that  it  will  prove  a  very  efiScient  aid  in  the  education 
of  the  young,  and  a  source  of  much  interest  and  in- 
struction to  the  adult  reader. 


THE  ENCYCLOPEDIA  AMERICANA. 

A  POPULAR  DICTIONARY  OF 

Arts,  Sciences,  Literature,  History,  Politics,  Biography; 

INCLUDING 

A  COPIOUS  COLLECTION  OF  ORIGINAL  ARTICLES  IN  AMERICAN  BIOGRAPHY. 

ON  THE  BASIS  OF  THE  SEVENTH  EDH  ION  OF  THE  GERMAN 

CONVERSATIONS-LEXICON. 

Edited  by  FRANCIS  LIEBER, 

Assisted  by  E.  WIGGLESWORTH  and  T.  G.  BRADFORD. 

With  Additions  by  Pkofessor  HENRY  VETHAKE, 

Of  the  University  of  Pennsylvania. 

In  fourteen  large  octavo  volumes,  containing  in  all  nearly  nine  thousand  large  double-columned 

pages,  furnished  in  various  styles  of  binding,  at  very  low  prices. 

THE   GEOLOGICAL   OBSERVER. 


BY 

SIR  HENRY  T.  DE  LA  BECHE, 

C.  B.,  l\  R.  S., 

Director-General  of  the  Geological 

Survey  of  the  United  Kingdom. 

WITH 
OVER  THREE  HUNDRED 

In  one  very  large  and  handsome 

octavo  volume,  of  700  pages, 

extra  cloth,  $4  00. 


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